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Audio - Visual Device Manual

1. LLI 5 ECC serial or Ethernet Speakers E port Experiment control Mouse computer running an experiment 1 4 miniplug extension cord Keyboard mei 5 Drawing is not to scale AV Device Audio cable Figure 3 3 AV Device setup for auditory stimuli Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 49 3 Auditory Stimulus Testing Software Configuration Setting up the software for experiment control involves configuring Net Station to record and display auditory stimuli Configuring Net Station The instructions for configuring Net Station for auditory stimuli are nearly identical to those for visual stimuli Therefore 1 Follow Steps 1 12 beginning on page 34 of Chapter 2 Visual Stimulus Testing One exception In Step 6 on page 35 click on the second box from the right to turn on DIN 2 and in the Code box type DIN2 if desired this is not required 2 To confirm that Net Station is receiving and displaying DINs in the Events control panel of the Dense Waveform Display On the ECC choose Start menu gt Settings gt Control Panel gt Sounds and Audio Devices to open the Sounds and Audio Devices Properties window Figure 3 4 volume Sounds Audio Voice Hardware Creative SB Livel Seres Device volume Volume slider Mute checkbox Place volume icon in the taskbar
2. 4 0 0 wo WW a Figure 3 6 Auditory ECI and DIN events in the Events control strip of the Dense Waveform Display 52 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 3 Auditory Stimulus Testing 4 Ifyou see more than one DIN per auditory stimulus make sure that you have selected DIN 2 for the stimulus duration in the Setup Single Channel Input window see Figure 2 5 on page 36 If DIN 2 is selected but multiple DIN persist contact EGI Technical Support Appendix A 5 Complete the experiment and press Return to exit when prompted to do so 6 Exit NetStation which will automatically save the timing results file as a Net Station Recording Viewing the Results To view the results launch the Event Timing Tester program and open the Net Station timing results file For information about how to use the Event Timing Tester see Chapter 4 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 59 3 Auditory Stimulus Testing 54 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 4 EVENT TIMING TESTER he Event Timing Tester is a drag and drop application that extracts event timing information from a Net Station file Specifically the Event Timing Tester compares offsets between the Net Amps DIN and the Net Station ECI events For more information about the Net Amps digital inputs see the GES Hardware Technical Manual For more information about Net
3. Speaker settings i Uze the settings below ta change individual speaker volume and other settings Speaker Volume Figure 3 4 The Sounds and Audio Devices Properties window 50 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 3 Auditory Stimulus Testing 5 In the Sounds and Audio Devices Properties window adjust the volume slider As you do so you should see a DIN event in the Events control panel of the Dense Waveform Display Figure 3 5 Figure 3 5 The DIN events for an auditory stimulus experiment Net Station is now ready to communicate with the ECC to record data and events and to display ECI and DIN events in the Dense Waveform Display Verifying AV Device Functionality 1 On the ECC open the Sounds and Audio Devices Properties window by choosing Start menu Settings Control Panel Sounds and Audio Devices 2 IntheSounds and Audio Devices Properties window make sure that the Mute checkbox is unselected see Figure 3 4 on page 50 3 Watch the DIN2 LED on the AV Device while adjusting the volume slider in the Sounds and Audio Devices Properties window 4 The DIN2 LED should illuminate If it fails to light up check the cable connections 5 Ifthe LED still fails to illuminate see Chapter 5 Troubleshooting for solutions Note If the LED still remains unlit contact EGI Technical Support Appendix A Audio Visual Device Technical Manual S MAN AV
4. 7 2007 Contacting EGI EGI Support webpage www egi com support bim Email support support egi com Sales info egi com information Telephone 1 541 687 7962 Fax 1 541 687 7963 Address Electrical Geodesics Inc 1600 Millrace Drive Suite 307 Eugene OR 97403 USA 69 A Technical Support Contacting PST This manual describes using the AV Device in conjunction with EGI s GES ECC systems and PST s E Prime software PST produces two manuals devoted to the interaction between E Prime and Net Station the E Prime Extensions for Net Station User Manual and the E Prime Biological Add ons to Net Station User Manual as well as a manual about programming E Prime experiments E Prime User s Guide For questions about E Prime contact PST PST Support www pstnet com webpage e prime support Email support support pstnet com Sales info Qpstnet com information Telephone 0 Fax 412 271 7077 Address Psychology Software Tools 2050 Ardmore Boulevard Suite 200 Pittsburgh PA 15221 4610 USA 70 Audio Visual Device Technical Manual S MAN AV 001 May 7 2007 Audio Visual Device Technical Manual GLOSSARY A Acquisition Setup file A saved Workbench configuration that preserves the control and display settings that were in effect at the time the file was saved A setup can be multipurpose or specialized for specific acquisition needs depending on t
5. LEDs on the AV Device may light up In addition to the other LEDs verify that the correct DIN LED is definitely illuminated 5 DINI visual stimuli on CRT monitors 5 DIN3 visual stimuli on LCD monitors 3 Ifthe correct LED fails to illuminate see Chapter 5 Troubleshooting for solutions 4 RepeatSteps 1 3 until the correct LED illuminates 5 Abort the experiment by pressing Control Alt Esc Test Instructions ECI events are those received by Net Station via the Multi Port ECI interface In our case these are the events sent by E Prime Don t worry if events seem to appear late in the Net Station display If Net Station is busy the display may lag a bit in the interests of preserving other more vital actions e g writing to disk The important thing is to confirm that both DINs and ECI events are being transmitted by noting them in the Events control strip Running the Test 1 Start your own E Prime experiment or NSTiminglest es 2 Verify that E Prime is successfully transmitting events to Net Station as evident in the Events control strip of Net Station s Dense Waveform Display Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 A 2 Visual Stimulus Testing and that Net Station is recording data to disk as evident in Net Station s Waveform Recorder Controls panel 3 When a stimulus is presented onscreen both the ECI event and the corresponding DIN should be visible in the Events control s
6. These ports allow the Inputs ports to be recorded as EEG input as well as DINs so that the timing can be compared These controls are not used by EGI and consequently are not discussed further in this manual 5 Inputs ports Allow input from passive photocells line level audio or strip chart recorders The Photocell and Audio ports are used for testing visual and auditory stimuli and are discussed in Chapter 2 and Chapter 3 respectively The Chart port accepts output from any analog device that has at least 1 Vpp output e g a strip chart recorder The Chart port is ot used by EGI and consequently is not discussed further in this manual DIN Specifics DIN is an acronym for digital inputs During testing with the AV Device stimuli detected by a photocell or speaker are converted from analog to digital form and transmitted to the amplifier as DIN events by way of the DIN patch cable The three duration values of the AV Device digital output are 20 milliseconds e 100 milliseconds e Actual These duration values correspond to the following stimuli type respectively e visual stimuli presented on cathode ray tube CRT monitors e auditory stimuli e visual stimuli presented on liquid crystal display LCD monitors While setting up the testing configuration described further in Configuring Net Station on page 34 you specify the stimuli type in Net Station s Setup Single Channel Input window by selecting the corresponding
7. chapter provides solutions to problems you may experience while operating or configuring the AV Device The topics covered in this chapter include general troubleshooting visual stimuli and subject auditory response General Troubleshooting The section discusses problems that may occur while configuring the AV Device for operation with the GES ECC setup DINs Fail to Illuminate If the DIN LEDs on the AV Device do not illuminate during a stimulus e Make sure the photocell or audio source is plugged in and that the AV Device is powered on e Test the photocell by exposing it to overhead lights e Test the audio input by connecting any suitable line level audio source If these tests succeed and the DIN LEDs still do not illuminate contact EGI Technical Support Appendix A Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 63 5 Troubleshooting DINs Always Lit When testing a black stimulus on a white background you may notice the DIN LEDs on the AV Device not turning off when the stimulus is presented 1 First turn both the brightness and contrast down on the stimulus presentation monitor s controls 2 Ifthe DIN still does not turn off when the stimulus is visible try increasing the size of the stimulus also check that the photocell sleeve has not fallen off or become dislodged DINs Not Visible in Net Station If the DIN events fail to appear in Net Station s Events control strip check the f
8. experiment file 38 2 9 The photocell holder positioned for a visual stimulus experiment 39 2 10 AV Device setup for visual stimuli 40 2 11 Visual ECI and DIN events in the Events control strip of the Dense Waveform Display 42 chapter 3 Auditory Stimulus Testing 3 1 The AV Device connected properly for auditory stimuli using the Net Amps 300 47 3 2 The audio cable plugged into the miniplug port on the back ofthe ECC 48 3 3 AV Device setup for auditory stimuli 49 Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 VII List of Figures 3 4 The Sounds and Audio Devices Properties window 0 3 5 The DIN events for an auditory stimulus experiment 51 3 6 Auditory ECI and DIN events in the Events control strip of the Dense Waveform Display 2 chapter 4 Event Timing Tester 4 1 Event Timing Tester application 55 4 2 Event Timing Tester 56 4 3 The DAC and ECC clocks can drift away from real time and from each other 60 VIII Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 LIST OF TABLES chapter 1 Technical Overview 1 1 AV Device package hardware 9 Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 List of Tables Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 he Audio Visual AV Device from Electrical Geodesics Inc EGI is a product for verifying the accuracy of stimulus presentation timing for event relate
9. s internal clock may drift away from real time and from each other during the duration of any experiment Figure 4 3 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 59 4 Event Timing Tester Real Time to 1 00 Real Time After nine hours the real time clock points to 10 00 DAC Clock DAC Clock However the DAC clock runs fast and points to 10 05 having drifted 5 minutes ahead of real time and 10 minutes ahead of the ECC clock during the nine hours ECC Clock Before the experiment real time the DAC clock and the ECC clock are all synchronized each pointing ECC Clock In contrast the ECC clock runs slow and points to 9 55 having drifted 5 minutes behind real time and 10 minutes behind the DAC clock during that same time period Figure 4 3 The DAC and ECC clocks can drift away from real time and from each other Such drift can introduce an error into the experiment data that causes events to be skewed with respect to the corresponding EEC Clock Drift Solutions To correct for clock drift use one of the following e the clock synch approach e aclock scaling factor or e single clock 60 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 4 Event Timing Tester Clock Synch Accumulated drift is corrected every time the DAC and ECC synchronize their clocks Because clock accuracy is partly machine dependent the actu
10. shows the Workbench configured as described disregard the event stream and waveforms for now Net Station is now ready to communicate with the ECC to record data and events and to display ECI and DIN events in the Dense Waveform Display Presenting the Visual Stimuli This section describes how to position the photocell based on the onscreen stimuli presented by the EGI E Prime timing file or by your own E Prime experiment Using the EGI E Prime Timing File If you are using NSTiming lest es 1 Use the Search function Start menu gt Search gt For Files or Folders to locate this file on your ECC if necessary contact EGI Technical Support Appendix A 2 Open the file and click the Run button Figure 2 6 0 ies es E Slud The Run button LLEVE II S Figure 2 6 Click the Run button to begin onscreen instructions for the NSTimingfest es file Audio Visual Device Technical Manual S MAN AV 001 May 7 2007 37 2 Visual Stimulus Testing 3 Follow the onscreen instructions which will guide you in the proper placement of the photocell holder Figure 2 7 Figure 2 7 The photocell holder positioned for the NSTiminglest es file Using Your Own E Prime Experiment If you are testing your own E Prime experiment 1 Open the NSInit object in your experiment file and set the second parameter to off to disable communication with Net Station Figure 2 8 Properties NSInit General Not
11. 001 e May 7 2007 5l 3 Auditory Stimulus Testing Test Instructions For information about testing read the three paragraphs following the section title Test Instructions on page 41 Running the Test 1 Start your own E Prime experiment or SPTimingl est es 2 Verify that E Prime is successfully transmitting events to Net Station as evident in the Events control strip in Net Station s Dense Waveform Display and that Net Station is recording data to disk as evident in Net Station s Waveform Recorder Controls panel 3 When a stimulus is presented via the audio source both the ECI event and the corresponding DIN should be visible in the Events control strip of the Dense Waveform Display Figure 3 6 5 43 File Edit Doers Acq Panels Record Net Deplay Time Amplitude Events a Thu 11 74 AM 00 36 35 wh proper Urad lorng F on Dense Waveform Display CC legt Control Wee e ame BOON Tee Sale Amphnade ee Fame m sl S rien idl Saca Trace em et Dn eeh Teen spec bode bads comm mota ee maia iarrt tata DIN and ECI events E Filter 100 Lipan 88141 D 1Hz Hegpact re Feu must plug in A Net before acquiring or measuring impedance i Li a b Wo wuwuuss 4 Ww x o4 WV Y 5 HS OH VS X ON Ww 5
12. 007 43 2 Visual Stimulus Testing 44 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 3 AUDITORY STIMULUS TESTING his chapter describes how to test the precision of auditory stimulus presentation using the AV Device The topics covered in this chapter include general considerations such as basic experiment requirements hardware configuration software configuration verifying AV Device functionality and test instructions General Considerations The EGI E Prime timing test meets all the testing requirements If you are testing the timing of your own E Prime auditory stimulus experiment the experiment must have the following features Identical setup If possible we recommend using the actual experiment If this is not possible then the experiment should be as similar as possible to the actual experiment in particular stimulus type and loudness GES and ECC configurations and software versions should be identical e Full duration If possible we recommend using the actual experiment If this is not possible then the duration number of trials and blocks of trials should be as the experiment will be used Timing errors accumulate testing a short version of an experiment does not certify a longer version e Audible stimuli The auditory stimulus must be loud enough to trigger the AV Device e Rapid ramp up The auditory stimulus should have a reasonably abrupt volume increase at
13. 1 on page 22 for photos and descriptions of the AV Device components mentioned in the following steps 1 Connectthe DIN patch cable from the 9 pin DINs Output port on the top of the AV Device to the 9 pin DIN port on the amplifier 46 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 3 Auditory Stimulus Testing O For the Net Amps 200 the DIN port is located on the back panel and labeled Digital Inputs If using a 256 channel system plug the DIN patch cable into the DIN port on the master amplifier O For the Net Amps 300 the DIN port is located on the back panel and labeled digital pins 1 8 for the Net Amps 300 however you will first need to plug the DIN patch cable into the provided adapter and then plug the adapter cable into the DIN port Verify that the DIN patch cable is firmly seated at both ends 2 Plug the power supply cord into a surge suppressed power socket 3 Plug the other end of the power supply cord into the port labeled 9 VDC on the top of the AV Device 4 Plug either of the audio cable s RCA plugs into the Audio port on the front of the AV Device Figure 3 1 shows the AV Device connected to a Net Amps 300 Adapt DIN patch De Adapter Power supply cord cable cable 9 VDC DINs Output digital pins 1 8 OO OO Net Amps 300 Power socket 1 4 miniplug Drawing is not to scale Figure 3 1 The AV Device connected properly for auditory stimuli u
14. 5 Hardware Configuration 46 Software Configuration 50 Verifying AV Device Functionality 51 Test Instructions 52 Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 VI Contents chapter 4 chapter 5 Appendix A Event Timing Tester 5 Event Timing Tester Interface 56 Running the Event Timing Tester 58 Analysis of Results 59 Text Output 62 Troubleshooting 3 General Troubleshooting 63 Visual Stimuli 65 Technical Support 69 Before Contacting 69 Contacting EGI 69 Contacting PST 70 Glossary 7 Index 75 Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 LIST OF FIGURES chapter 1 Technical Overview 1 1 The AV Device 22 1 2 Experiment control diagram 25 1 3 ECI and DIN events in Net Station s Events control strip 26 1 4 Averaged ERP 27 1 5 Averaged ERP with misalignment 28 chapter 2 Visual Stimulus Testing 2 1 The AV Device connected properly for visual stimuli using the Net Amps 300 33 2 2 Net Station AV Device setup 34 2 3 Opening the Digital Input Controls panel 35 2 4 Opening the Setup Single Channel Input window 35 2 5 Selecting the correct digital input for a variety of stimuli 36 2 6 Click the Run button to begin onscreen instructions for the NSTimingTest es file 37 2 7 The photocell holder positioned for the NSTimingTest es file 38 2 8 Change the NSInit object in your own E Prime
15. DIN DIN 1 featuring a 20 millisecond duration this is suitable for visual stimuli presented on CRT monitors e DIN 2 featuring a 100 millisecond duration this is suitable for auditory stimuli Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 23 1 Technical Overview 24 e DIN 3 the actual signal this is suitable for visual stimuli presented on LCD monitors If the equipment is connected correctly the corresponding DIN LED on the AV Device will illuminate accordingly during operation Basic Event Timing Theory To understand how the AV Device works some background on ERP system configuration and EEG event miscorrelation is needed System Configuration ERPs are averaged EEG waveforms elicited by external stimuli Typical external stimuli might be sounds shapes or words though the type of stimulus is limited only by the experimenter s resourcefulness EGI offers a two system approach to ERP studies the GES and the ECC system The GES generally consists of e the data acquisition computer DAC running Net Station e amonitor e computer peripherals such as a keyboard and a mouse e aNet Amps 200 or 300 amplifier e a Geodesic Sensor Net GSN e required cabling a subject response pad optional The ECC system generally consists of e the ECC running the experiment control software E Prime is the software used in the ECC systems offered by EGI e an experimenter s monitor astim
16. Effect on a Single Recording For a single trial miscorrelation has the result of skewing the EEG and the stimulus by some number of milliseconds potentially confusing what is evoked and what is background EEG Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 1 Technical Overview Effect on Averaged ERPs For an averaged ERP miscorrelation between event and EEG has a potentially more serious effect Averaged ERPs help determine the constant cross subject response to a given stimulus One way researchers create averaged ERPs is by selecting regions of EEG around a given stimulus type a process called segmentation aligning all the EEG segments so that their causal events coincide and averaging the pieces together What s left is a smoothed ERP with little of the incidental or background EEG Figure 1 4 Averaged ERP Figure 1 4 Averaged ERP Audio Visual Device Technical Manual S MAN AV 001 May 7 2007 2 1 Technical Overview If offsets between event and EEG vary from segment to segment the individual EEG segments are misaligned when indexed by causal event Figure 1 5 Averaged ERP Figure 1 5 Averaged ERP with misalignment The result is an averaged ERP that is blurred temporally and less distinct than it would be with proper indexing In extreme cases the averaged ERP may vanish entirely because of event EEG miscorrelation 28 Audio Visual Device Technical Man
17. Electrical 6260065105 Inc Audio Visual Device Technical Manual Audio Visual Device Technical Manual Electrical Geodesics Inc Riverfront Research Park 1600 Millrace Drive Suite 7 Eugene OR 97403 info egi com www egi com Audio Visual Device Technical Manual S MAN 200 AV 001 7 2007 Electrical Geodesics makes no warranty or representation either express or implied with respect to this manual its quality accuracy merchantability or fitness for a particular purpose In no event will Electrical Geodesics be liable for direct indirect special incidental or consequential damages resulting from any defect or inaccuracy in this manual even if advised of the possibility of such damage Copyright 2007 by Electrical Geodesics Inc All rights reserved E G dense array EEG CONTENTS List of Figures vii List of Tables ix Preface xi Related Manuals xi About This Manual xv Troubleshooting and Support xvi chapter 1 Technical Overview 7 When to Use the AV Device 17 Overview of AV Device Operations 18 AV Device Package 19 AV Device Features 22 Basic Event Timing Theory 24 chapter 2 Visual Stimulus Testing 29 General Considerations 29 Hardware Configuration 30 Positioning the Photocell Holder 33 Verifying AV Device Functionality 41 Test Instructions 41 chapter 3 Auditory Stimulus Testing 5 General Considerations 4
18. Event Timing Tester and correcting for clock drift time offsets and other timing errors Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 55 4 Event Timing Tester Event Timing Tester Interface The Event Timing Tester coordinates viewing of DIN and ECI events in a single simple interface Figure 4 2 shows the Event Timing Tester interface Toshiba VTD Timing test 1 2 Stim Event Code stm 5 3 DIN Event Code DIN1 4 Observation Rel Time Elapsed Time 1 1 1 3557 17 0 2 1 2 oF Bet 16 2207 3 1 3 1 17 2207 4 1 4 10176 16 eel 5 1 5 12385 17 2207 b 1 b 14532 16 2207 7 1 H 15733 17 2207 8 1 8 19006 2207 3 1 3 21215 5 2209 10 1 10 23421 17 2206 11 1 11 25620 16 2207 12 1 12 27035 17 2207 13 1 13 30042 16 2207 14 1 14 32249 17 2207 15 1 15 34456 16 2207 16 1 16 36663 17 2207 17 1 17 38670 16 2207 18 1 18 41077 17 2207 1 13 1 13 43284 16 2207 2l 1 20 45491 1 2207 Y 5 220 E Figure 4 2 Event Timing Tester The following are brief descriptions of the numbered items from Figure 4 2 1 Stim Event Code pop up menu Displays all the event codes extracted from the selected timing results file You must choose the Stim event that corresponds to your ECI event 2 DIN Event Code pop up menu Displays all the event codes extracted from the selected timing results file You must choose the DIN event that corresponds to your DIN event 3 Create Timing Table button Wh
19. Figure 2 3 Opening the Digital Input Controls panel 5 Click the Events tab and in the Events tabpanel click the Single Channel button to open the Setup Single Channel Input window Figure 2 4 Digital Input Controls Setup Single Channel Input Input _ Source Tracks Events Select Channel LIEIEIEIEJEIEIISI Edge Pulse 8 1 Simple Event Setup Event 4 Channels d i Channels Code DIN 4 Characters 15 Channels e Use Global Counter Key 4 Characters Max 255 Channels Me a P Set To Default Cancel Advanced Event Setup M 255 Active Events Figure 2 4 Opening the Setup Single Channel Input window 6 Configure the Setup Single Channel Input window as follows 5 f the stimulus presentation monitor is a CRT click on the box labeled 1 to turn on DIN 1 f the stimulus presentation monitor is an LCD click on the third box from the right to turn on DIN 3 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 35 2 Visual Stimulus Testing 5 n the Code box type DINI or DING if desired this is not required 5 Leave the Edge button and the Use Global Counter Key checkbox selected Click the OK button Figure 2 5 Setup Single Channel Input DIN 1 Select for visual stimuli presented on a CRT Input DIN 2 Sele
20. MAN AV 001 e May 7 2007 29 2 Visual Stimulus Testing Large stimuli The visual stimulus must be large enough 3 millimeters or about 0 125 inch to trigger the photocell Wider stimuli make positioning the photocell easier High contrast The visual stimulus should be high contrast e g white stimuli on a black background Low contrast stimuli can fail to trigger the photocell at all or conversely can trigger the photocell erroneously at all times e Bright stimuli White stimuli are recommended Black stimuli are problematic and should be avoided for testing purposes see Chapter 5 Troubleshooting If the experiment lacks some or all of these features it may still be testable in a modified form Contact EGI Technical Support for assistance Appendix A Hardware Configuration You will need the following e AV Device with power supply cord DIN patch cable photocell and photocell holder aGES ECC setup The GES and ECC setup shown in Figure 1 2 on page 25 is the two machine configuration that is normally used for stimulus presentation and data collection Note During timing tests the GSN typically is not connected to the amplifier GES Configuration The GES which represents the data acquisition part of the ERP setup consists of the GSN a Net Amps 200 or 300 amplifier a DAC running Net Station a monitor and cabling e g connecting the amplifier to the DAC 30 Audio Visual Device Technical Manu
21. Station ECI events see the Net Station Acquisition Technical Manual For more information about using the AV Tester see either Chapter 2 Visual Stimulus Testing or Chapter 3 Auditory Stimulus Testing The Event Timing Tester is installed as part of the Net Station package in the Extras folder Figure 4 1 eoo Extras pes Q a TOU Reiden Kai 1 i d e m i m A Network 1 Macintosh HD a pete oe pu 8 Mail ALL ese Fever rA ME x ih 2 erver log 3 MAXON d L 8 Event Timing Tester vem iming Tester EA Network LA App eege e Microsoft AutoUpdate File 0 mE Desktop Applications Mac OS 9 Microsoft Office 2004 Net Station Br Net Station File Exporter Desktop 3 National i NS Remote SP Updater A Applications Desktop Mac OS 9 gt 2 Sensor Layout Separator 3 sa Maier FE Net Station sktop Folder 1 0 L Sege bs Document 1 8 kee Installer Log File Seen H Pictures GB Library Le OmniOutliner _ Event Timing 1 s a Preview A Wi i L Media e 3 QuickBooks NUE Tester Movies Gi Microsoft Office 2001 QuickTime Player 1 l 6 items 35 61 GB available Figure 4 1 Event Timing Tester application The topics covered in this chapter include interface features using the interface analyzing the results of the
22. al S MAN AV 001 e May 7 2007 2 Visual Stimulus Testing Before running an EGI E Prime timing test or your own E Prime experiment you should test the GES for basic functionality e g acquiring and recording data from the amplifier During timing tests the GSN typically is not connected to the amplifier For further information about Net Station and the amplifier see the Net Station Acquisition Technical Manual and the GES Hardware Technical Manual ECC Configuration The ECC which represents the experiment control part of the ERP setup consists of an ECC running E Prime an experimenter s monitor a stimulus presentation monitor for the subject a serial or TCP IP cable connecting the ECC to the DAC other cabling and single clock hardware if TCP IP is used Computer peripherals such as the keyboard and mouse may be omitted depending on the laboratory setup For instructions on installing the single clock hardware see the E Prime Extensions for Net Station User Manual Note The E Prime Extensions for Net Station User Manual may not identify the timing port for the Net Amps 300 This port is located on the amplifier s back panel and is labeled digital pins 9 16 Before running an EGI E Prime timing test or your own E Prime experiment you should test the ECC setup for basic functionality e g presenting stimuli in E Prime logging events in Net Station and recording data For further information about E Prime and exp
23. al frequency with which clock synchronization should be performed is best determined empirically by running a test without clock synching and determining the clock drift rate For instructions on how synchronize your clocks see page 216 Command of Appendix G Experimental Control Protocol in the GES Hardware Technical Manual The Note at the bottom of page 216 provides additional information Clock Scaling Factor The ECC clock and the DAC clock each has a small fraction of error in its designated frequency If left unchecked a linear cumulative clock drift will occur between the two clocks You can adjust the ECC event times using a scaling factor calculated with the AV Device A clock scaling factor determines the difference between the two clocks and provides a conversion factor that corrects for the difference For full instructions see the E Prime Biological Add ons for Net Station User Manual EGI s Single Clock Clock drift primarily occurs because of the difference between the ECC and DAC clocks You can eliminate clock drift completely by using EGI s single clock solution which allows the ECC to read the DAC clock and use that as its time base The single clock is available for use only with E Prime For full instructions see the E Prime Extensions for Net Station User Manual or contact EGI Technical Support Appendix A Note Single clock eliminates only clock drift it is still necessary to use the AV D
24. and rapidly flashing updates in sequence they give the illusion of constant illumination much like a fluorescent light flickering at 60 Hz seems to constantly be emitting light CRT monitor refresh rates vary both with the monitor and with the particular monitor setting Commonly though monitors update each pixel 60 75 or 120 times a second Choosing DIN 1 in the Setup Single Channel Input window of the Digital Input Controls panel allows Net Station to automatically compensate for typical CRT monitor refresh rates of 16 18 milliseconds by integrating over 20 milliseconds This digital output consequently has a single digital output state per monitor stimulus instead of the periodic 16 millisecond spikes typical of unintegrated photocell detectors LCD monitors on the other hand pass a continuous stream of light to each pixel and dim a pixel only when instructed to do so Choosing DIN 3 in the Setup Single Channel Input window allows the actual signal to trigger the digital output to Net Station Stimuli Positioning on CRT Monitors Because monitor refreshes begin at the top of CRT monitors there can be discrepancies related to the position of the stimulus on the screen E Prime sends the signal marking stimulus onset as the refresh begins at the top of the CRT monitor If your stimulus is positioned at the top of the monitor there should be no offset related to positioning stimulus positioned at the bottom of the monitor howev
25. connected to a power supply and equipped to receive a plug reference An electrical point that is treated as zero for purposes of amplifying electrical signals The Geodesic Sensor Net has a reference electrode located at the vertex refresh rate The frequency with which each pixel on a particular monitor is updated with new information This is expressed in Hertz S sample When a continuous signal is measured by examining it at discrete moments in time each measurement corresponds to a sample sampling rate The number of times per second that data are temporally sampled segment of EEG discrete portion of EEG and the product of segmentation segmentation The process of breaking a continuous recording of EEG into discrete sections of equal length usually 73 74 centered around one or more causal events signal A detectable measurable quantity that can be expected to display periodicity or other forms of variation in time socket An opening or cavity into which something fits spatial sampling The process of sampling a 3D space at regular location intervals in a given instant of time Compare with temporal sampling stimulus An event presented to a subject usually to elicit an ERP T temporal sampling The process of sampling a given location at regular intervals in time Compare with spatial sampling trial A single observation in an E Prime file or a single segment of EEG with cor
26. cord into the port labeled 9 VDC on the top of the AV Device 5 Plug the photocell jack into the Photocell port on the front of the AV Device 6 Fitthe photocell into its receptacle in the assembled photocell holder 32 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 2 Visual Stimulus Testing Figure 2 1 shows the AV Device connected to a Net Amps 300 Adapt DIN patch Ste Adapter cable cable Power supply cord bs 9 VDC DINs Output digital pins 1 8 eX OO AV Device Net Amps 300 Photocell Photocell holder Drawing is not to scale Figure 2 1 The AV Device connected properly for visual stimuli using the Net Amps 300 Positioning the Photocell Holder The photocell holder must be placed flat against the stimulus presentation monitor and positioned so that it is directly over the stimulus for which you wish to verify timing To do this you must run both Net Station and E Prime to display the stimulus on the stimulation presentation monitor Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 33 2 Visual Stimulus Testing Configuring Net Station For assistance in creating or modifying a Workbench setup or in using Net Station consult the Net Station Acquisition Technical Manual 1 Openan existing Acquisition Setup or create a new one 2 With the Workbench off configure it so that it includes the four devices connected as shown in Figure 2 2 if your GES
27. ct for auditory stimuli Select Channel DR Ll fe Edge Pulse DIN 3 Select for visual stimuli presented on an LCD Event Code 4 Characters Use Global Counter Key gidx 4 Characters Max Set To Default Cancel ok Figure 2 5 Selecting the correct digital input for a variety of stimuli 7 The Digital Input Control panel is now defined drag it to the right side of the window 8 You will use the Waveform Recorder Controls panel to view event information during acquisition Because it requires no configuration drag it to the right side of the window 9 Inthe Multi Port ECI panel click the Log button to open the Session Log which allows you to monitor ECI events during acquisition and click the Long Form button drag both the Multi Port ECI panel and the Session Log to the right side of the window 10 In the Dense Waveform Display panel click the Events button near the top of the window to open the Events control strip which allows you to view event markers during acquisition drag the window to its maximum size 11 Turn on the Workbench by clicking the On button in the upper right corner of the Acquisition status panel 12 Disregard any dialog that appears notifying you that a Net must be plugged in before acquiring data or measuring impedances 36 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 2 Visual Stimulus Testing Figure 2 11 on page 42
28. d potentials ERPs The AV Device can be used for two purposes e To verify that the system timing is correct e To verify that an experiment is programmed correctly Designed to work with EGI s Net Station electroencephalography EEG acquisition analysis and review software the AV Device is an option to Geodesic EEG Systems GES that are configured for experiment control These GES can operate in conjunction with either a PC based experiment control system that is available from EGI or with your own experiment setup This manual describes EGI s experiment control system which uses E Prime software from Psychology Software Tools PST www pstnet com Note For more information about using the AV Device with other experiment control software and setups contact EGI Technical Support Appendix A Related Manuals This manual the Audio Visual Device Technical Manual describes timing theory the AV Device s features visual stimulus testing auditory stimulus testing the Event Timing Tester and troubleshooting tips Because this manual describes only one component of the experiment control process it will be helpful to consult other documentation from EGI and PST when using the AV Device to conduct timing tests Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 xi ECI Documentation Descriptions related to experiment control are included in two other EGI manuals e Net Station Acquisition Technical Manual d
29. d Elapsed Time columns Running the Event Timing Tester The Event Timing Tester is an easy to use application 1 Find the Event Timing Tester which is located in the Extras folder of the Net Station folder on your hard drive see Figure 4 1 on page 55 2 Tolaunch the Event Timing Tester drag a Net Station Recording file saved from a timing test see Step 6 on page 42 or Step 6 on page 53 if needed onto the Event Timing Tester icon to highlight the application and release 3 Inthe Event Timing Tester window select the desired Stim ECI and DIN event codes from the pop up menus For example if the data file in question resulted from using the AV Device to measure a visual stimulus onset presented on a CRT monitor and if DIN1 was recorded by Net Station in Figure 4 2 you would select stm and DINI for the Stim ECI and DIN event codes respectively 4 Click the Create Timing Table button to update the table For each trial the corresponding Cell Observation Relative Time Offset and Elapsed Time is displayed If the ECC did not follow E Prime conventions the fields for Trial Cell and Observation will display a question mark 58 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 4 Event Timing Tester Analysis of Results The values calculated by the Event Timing Tester allow you to determine if the system timing is operating within specifications or if the E Prime experiment is programmed cor
30. d an x stimulus the correct location for the photocell holder would allow both the o and the x pixels to fill the aperture If this is impossible you can run the test multiple times making sure that the stimuli are covered in the other runs Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 39 2 Visual Stimulus Testing The finished setup is shown in Figure 2 10 GES setup Monitor USB or Data acquisition FireWire cable computer running Power Net Station socket DIN port Amplifier DIN patch cable Power supply cord Adapter for Net Amps 300 l 9 VDC DINs Output ECC setup Stimulus presentation monitor Experimenter s monitor Serial or Ethernet cable Photocell ECC serial or Ethernet port AV Device Experiment control Mouse computer running Photocell holder an experiment Drawing is not to scale Figure 2 10 AV Device setup for visual stimuli 40 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 2 Visual Stimulus Testing Verifying AV Device Functionality Before acquiring timing data check that the AV Device functions properly 1 Run your own E Prime experiment NSTimingTest es 2 Allthe
31. e AV Device and an EGI E Prime timing file to verify that the system timing is operating within specifications During system installation After installing the equipment your EGI Support Engineer uses the AV Device and an EGI E Prime timing file to verify that the system timing is operating within specifications e Before running a study based on a new paradigm The customer should use the AV Device and his or her actual E Prime experiment before acquiring study data to verify that the system timing is operating within specifications Out of specification results often indicate that the experiment is programmed incorrectly Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 17 1 Technical Overview 18 e After making major changes to the hardware and software The customer should use the AV Device and an EGI E Prime timing file to verify that the system timing is operating within specifications Differences in computers operating systems and so forth may affect the timing and require changes to the setup e When troubleshooting timing problems The customer should use the AV Device and an EGI E Prime timing file to help pinpoint suspected timing errors EGI provides two E Prime timing files with your experiment control computer ECC NSTimingTest es for visual stimuli and SPTimingTest es for auditory stimuli You can use the Search function Start menu Search For Files or Folders to locate these files on
32. e question of how to determine when the subject is actually perceiving the stimuli Black stimuli on white background can pose problems for LCD monitors as well If the stimulus is too small and the white background is detected by the photocell it can erroneously trigger the photocell In this case you should increase the size of the stimuli so that no part of the background is detected by the photocell In general black stimuli on a white background are not a preferred test mode for either CRT or LCD monitors Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 67 5 Troubleshooting 68 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 Audio Visual Device Technical Manual appendix A TECHNICAL SUPPORT Before Contacting EGI Please check the Contents on page v and the Index on page 145 for coverage of your issue or question You can also perform an electronic search using Find or Search in the PDF version of this manual posted on the Documents page of the EGI website www egi com documentation html In addition the Support page of the EGI website www egi com support html may have the information you need If you need more help EGI recommends the following Try to isolate the problem Is your problem well defined and repeatable Document the problem Carefully record and organize the details gleaned from the above step and report the problem to EGI S MAN AV 001 e May
33. econd J jack Socket or connector into which a plug may be inserted M miscorrelation A misalignment between EEG and ECI events in a data file Miscorrelation causes errors in the average ERP S MAN 200 AV 001 e May 7 2007 Net Amps 200 and 300 EGI s dense array amplifiers Net Station EGI s Mac based data acquisition software Nyquist frequency The maximum frequency able to be characterized for a given sampling rate The Nyquist frequency is typically taken to be 2 5 of the sampling rate for engineering purposes also antialiasing observation The unit of analysis In a session file an observation is a single trial In an average file an observation is a single subject whose data have been averaged across trials offset A discrepancy between a DIN event and an ECI event in timing testing or between an ECI event and the corresponding EEG in a study See also miscorrelation P phosphor decay The time it takes for the intensity of the light emitted from the phosphor to fall off to10 of its original value pixel Asingle picture element A pixel is a point in 2D with a single color value The number of pixels visible on a monitor is controlled by the monitor s resolution setting Audio Visual Device Technical Manual S MAN 200 AV 001 May 7 2007 plug A fitting used to make electrical connections port A site for passing data in and out of a computer receptacle A fitting
34. en clicked calculates the Trial Cell Observation Relative Time Offset and Elapsed Time information for the selected timing results file given the Stim ECI and DIN event codes chosen 56 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 4 Event Timing Tester 4 Timing information Displays the information extracted from the selected timing results file Trial column displays the number of the trial in the file A trial is a single observation in an E Prime file A trial is usually defined as one cycle of a stimulus presentation in E Prime thus during normal operation it usually consists of a beginning event a stimulus event a response event and trial specifications Virtually all ERP experiments consist of a sequence of trials Cell column Displays the number of the cell in the file A cell is defined as a unique instance of the experiment condition being manipulated and provides a means of logically grouping the trials of an experiment into sets Trials are grouped into cells on the basis of stimulus characteristics not responses e g for an oddball task the standards are one cell and the targets or oddballs are another In Figure 4 2 all the trials visible 1 20 belong to Cell 1 Observation column Displays the number of the observation in the file An observation is a single trial of a particular cell In Figure 4 2 trials 1 20 belong to Cell 1 and are Observations 1 20 for that cell Re
35. ensive suite of applications E Studio E Basic E Run E Merge E Data Aid and E Recovery for generating experiments collecting data and handling and processing data Though the E Prime User s Guide which describes how to use E Prime to program experiments should be read in its entirety readers of the Audio Visual Device Technical Manual will find Chapter 3 Critical Timing in E Prime particularly useful The E Prime User s Guide is available from PST www pstnet com Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 About This Manual This section describes this manual s features organization conventions and typography and use of notes and cautions Features This manual is supplied as a PDF file and in printed form The hard copy version has been printed from the PDF so the content of both will match Manual Organization This manual features a table of contents list of figures list of tables and index which in the PDF are all hyperlinked to the topics they reference in the manual The chapters fall into four main categories e Background Chapter 1 Technical Overview describes the AV Device and basic timing technology e Testing Chapter 2 Visual Stimulus Testing and Chapter 3 Auditory Stimulus Testing describe how to use the AV Device to conduct timing tests of visual and auditory stimuli presentation e Results and Solutions Chapter 4 Event Timing Tester describe
36. er can have an offset of as much as 10 milliseconds You should account for the time offset when you segment the data For instructions see Time Offset on page 62 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 5 Troubleshooting Phosphor Decay on CRT Monitors Unlike LCD monitors CRTs are also subject to phosphor decay Phosphor decay is the time it takes for the intensity of the light emitted from the phosphor to fall off to 10 of its original value Suppose that you could view a single white pixel under magnification and very precisely in time You d notice that the pixel is brightly lit then fades out a bit while other pixels are being updated then is brightly lit again then fades a bit again over and over again 60 or 75 or 120 times a second At each refresh energy is rapidly sent to the pixel to keep it at the brightly lit state and to compensate for the partial dimming that occurs between refreshes The pixel does not blacken entirely between refreshes because it takes several cycles without energy for it to dim entirely to black Now consider a black pixel No energy is being routed to it and it consequently is not emitting photons When the command is given to make it turn white the monitor pours energy into that pixel on the next refresh cycle and it glows brightly almost immediately Pixels are thus faster changing from black to white than from white to black White o
37. eriment control see the E Prime Extensions for Net Station User Manual E Prime Biological Add ons for Net Station User Manual Net Station Acquisition Technical Manual or GES Hardware Technical Manual Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 3l 2 Visual Stimulus Testing Connecting the AV Device To connect the AV Device you will use the provided cabling to connect the device to the amplifier a power socket and the photocell See Table 1 1 on page 19 and Figure 1 1 on page 22 for photos and descriptions of the AV Device components mentioned in the following steps 1 Verify that the GES and ECC setups are powered on particularly the amplifier 2 Connect the DIN patch cable from the 9 pin DINs Output port on the top of the AV Device to the 9 pin DIN port on the amplifier For the Net Amps 200 the DIN port is located on the back panel and labeled Digital Inputs If using a 256 channel system plug the DIN patch cable into the DIN port on the master amplifier For the Net Amps 300 the DIN port is located on the back panel and labeled digital pins 1 8 for the Net Amps 300 however you will first need to plug the DIN patch cable into the provided adapter and then plug the adapter cable into the DIN port Verify that the DIN patch cable is firmly seated at both ends 3 Plug the power supply cord into a surge suppressed power socket 4 Plug the other end of the power supply
38. es Package NetStation e Routine Init e Parameters d rialList socket 10 0 0 91 Change the parameter to off Description Overview Initializes the Net Station system Parameters c As Context The current experiment context strState As String State of Net Station communications Toni off objCellList As List List that will be used as the Net Station cell list 1 Apply Figure 2 8 Change the NSInit object in your own E Prime experiment file 38 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 2 Visual Stimulus Testing 2 Run the experiment and position the photocell holder aperture flat against the monitor so that the aperture is completely filled by the stimulus Figure 2 9 In this experiment the photocell is placed such that the thick white circle of the stimulus completely fills the aperture of the photocell Figure 2 9 The photocell holder positioned for a visual stimulus experiment 3 Check for proper positioning by confirming that the illumination of the LEDs on the AV Device matches the appearance of the stimuli onscreen 4 Abortthe experiment by pressing Control Alt Esc 5 Open the NSInit object and set strState to on 6 If testing more than one stimulus type at once make sure that the aperture location covers both or all of the desired stimuli e g if the Visual Target Detection experiment features both an o an
39. es 18 Event Timing Tester analysis of results 59 interface 56 location of application 55 operation of 58 text output 62 event timing theory 24 Events control strip of Net Station 36 Events tabpanel of Net Station 35 Experimental Control Interface ECI events 26 G GES configuration 24 purpose 26 H hardware configuration auditory stimulus testing 46 visual stimulus testing 30 76 Audio Visual Device Technical Manual Inputs ports of AV Device 23 Isolated Outputs ports of the AV Device 23 L LED lights of the AV Device 3 M miscorrelation 26 more than one stimulus type testing of 39 Multi Port panel of Net Station 36 Net Station AV Device setup 34 9 VDC port of AV Device 22 NSInit object 38 phosphor decay 66 photocell for AV Device 20 photocell holder assembled for AV Device 20 38 39 positioning the photocell holder for visual photocell holder position of stimulus testing 33 power supply cable for AV Device 21 refresh rates 65 Run button of E Prime 37 5 Session Log of Net Station 36 Setup Single Channel Input window of Net Station configuring for DINs 35 Single Channel button of Net Station 35 single clock 61 S MAN 200 AV 001 e May 7 2007 Sounds and Audio Devices Properties window of the ECC 50 Source tabpanel of Net Station 35 stimuli type 23 strState 39 test instructions auditory stimulus testing 52 visual stimulus testing 41 time offs
40. escribes the features of the Multi Port Experimental Control Interface ECI device e GES Hardware Technical Manual describes the ECI setup and experiment control protocol These and other technical manuals from EGI are posted as PDF files at www egi com documentation html Brief descriptions of EGI s products and documentation follow or travel case The GES Hardware Technical Manual provides comprehensive descriptions of all GES hardware components and features 0 Hardware related e The Geodesic Sensor Net GSN is EGI s patented device for acquiring electrical signals from the human scalp The Geodesic Sensor Net Technical Manual provides comprehensive descriptions of all GSN features and functions e GES hardware is all the system hardware except for the GSN GES hardware supports the acquisition and processing of EEG data and includes an amplifier a data acquisition computer a monitor and in most cases a cart The Geodesic Photogrammetry System GPS is EGI s photogrammetry based sensor registration system The GPS consists of a geodesic dome structure containing 11 mounted cameras a steel supporting structure and the Photogrammetry software feature in Net Station The Geodesic Photogrammetry System Technical Manual provides comprehensive descriptions of all GPS components and features xil Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 Software related e The Net S
41. et 62 V verifying AV Device functionality auditory stimulus testing 51 visual stimulus testing 41 visual stimuli presented on a CRI DIN selection for 36 visual stimuli presented on an LCD DIN selection for 36 visual stimulus testing AV Device setup 40 basic experiment requirements 29 configuring Net Station 34 connecting the AV Device 32 ECI and DIN events in the Events control strip of the Dense Waveform Display 42 hardware configuration 30 positioning the photocell holder 33 test instructions 41 verifying AV Device functionality 41 W Waveform Recorder Controls panel of Net Station 36 Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 7 78 Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 EGI 1600 Millrace Drive Suite 307 Eugene OR 97403 1995 USA 1 541 687 7962 tel 1 541 687 7963 fax www egi com
42. evice to correct for time offsets Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 l 4 Event Timing Tester Time Offset With both the single clock and the two clock GES small offsets have been measured between the times reported for stimulus onset by E Prime and those detected by the AV Device Time Offset Solution One simple way to correct for time offsets is to account for them when segmenting the data You can do this by following these steps 1 Run the timing tests described in Chapter 2 Visual Stimulus Testing or Chapter 3 Auditory Stimulus Testing 2 Calculate the average offset using the Event Timing Tester see Running the Event Timing Tester on page 58 3 Enter the average offset value into the Offset text box in your Segmentation specification see the Segmentation chapter in the Net Station Waveform Tools Technical Manual Text Output To save a copy of the Event Timing Tester results choose File Save As Text File The resulting file is a tab delimited text file of the data shown in the Event Timing Tester interface A blank line separates blocks For best results view the file in a text editor that allows control over tab spacing e g StatView or Microsoft s Word or Excel Spacing should be about 15 characters or 1 inch per tab for best readability 62 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 5 TROUBLESHOOTING his
43. he devices included aliasing Distortion of the EEG signal which occurs when the signal is digitized at a rate less than half the highest frequency present See Nyquist frequency amplifier A circuit that increases the voltage current or power of a signal antialiasing Filtering a signal prior to digitization so that high frequency components do not appear as false lower frequency components See also Nyquist frequency C cable A group of two or more insulated wires S MAN 200 AV 001 e May 7 2007 causal event An event that is responsible for or associated with EEG This is usually a stimulus intended to elicit an event related potential ERP cell A category of data in an E Prime file that stores a single experimental condition For example one cell might contain all standards trials another all target trials connector Any plug and socket that links two devices together contact Current carrying part of a switch relay or connector correlation See miscorrelation D DAC See data acquisition computer data acquisition computer The computer running the EEG acquisition and review software dense sensor array Any sensor system that supports a sufficient number of sensors to adequately spatially sample a phenomenon For 72 EEG recording this generally means 32 channels or more digital input See DIN DIN ANet Amps digital input or an event caused by a Net Amps digital in
44. hods Each manual assumes you are familiar with the Macintosh computer the platform for Net Station Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 PST Documentation PST produces two technical manuals that describe how to use E Prime with Net Station These technical manuals are also available as PDF files at www egi com documentation html Brief descriptions of each manual follow e E Prime Extensions for Net Station EENS is a set of software extensions to E Prime that allow Ethernet communication between Net Station and E Prime during the run of an experiment The E Prime Extensions for Net Station User Manual describes EENS and single clock timing and EENS contains a set of sample experiments that can be run directly or used as a basis from which to create new experiments The E Prime Biological Add ons to Net Station EBANS is similar to EENS except it is designed for serial communication between Net Station and E Prime The E Prime Biological Add ons to Net Station User Manual describes EBANS and how to compute clock scaling factors and EBANS contains a set of sample experiments that can be run directly or used as a basis from which to create new experiments EBANS has been superseded by EENS but it is included in this manual for users who have not yet upgraded to EENS PST also produces a manual that describes how to use E Prime to program experiments e E Prime isa compreh
45. includes a Net Amps 200 use the Net Amps USB device as the Source device RECORDER i DISPLAY Waveform f Dense Waveform Se H Recorder 4 2 1 Sri 0 SOURCE mm Net Amps USB ue 4 2 E MARK STIMULATOR Device name Multi Port ECI Pg 1 001 e al Figure 2 2 Net Station AV Device setup 3 From the Panels menu choose the following Digital Input Controls Dense Waveform Display 5 Multi Port Waveform Recorder Controls The digital input you should use is determined by the type of stimulus presentation monitor and stimuli 4 Inthe Digital Input Controls panel click the disclosure toggle to open the window and make sure that the EGI Response Pad button is selected Figure 2 3 34 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 2 Visual Stimulus Testing Note These instructions assume a white stimulus on a black background For a black stimulus on a white background select the TTL button However black stimuli can be problematic for more information see Chapter 5 Troubleshooting Digital Input Controls C Digital Input Controls UI III D ep eg Clickie view the Source Tracks Events entire panel Use for virtually all AV testing applications 000 Response Pad Use for testing black stimuli a L white background Keyboard
46. l Time column Displays the time in milliseconds of the stimulus onset relative to the start of the file e g in Figure 4 2 Trial 1 begins 3557 milliseconds after the start of the file Offset column Displays the time in milliseconds between the trial s Stim event code e g stm and the nearest DIN event code e g DIN1 Following are some keys to interpreting offsets Positive values mean that the DIN appears after the Stim ECI event or that the actual stimulus appeared later than E Prime asserts Negative values mean that the DIN appears before the Stim ECI event or that the actual stimulus appeared earlier than E Prime asserts A question mark means that no DIN event code occurs 1 second of the Stim ECI event Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 57 4 Event Timing Tester e Elapsed Time column Displays the time in milliseconds from the last trial s Stim ECI event to the current trial s Stim ECI event This is also sometime referred to as the interstimulus interval or ISI In Figure 4 2 the Elapsed Time between trial 1 s stm and trial 2 5 stm is 2207 milliseconds Similarly the time between the stm s of trials 4 and 5 is 2207 milliseconds Note There can be no Elapsed Time for the first trial in a block 5 Averages Displays the average values calculated for Offset and Elapsed Time These are simply the means of the values in the Offset an
47. le 1 1 AV Device package hardware DIN patch cable Ke Power supply cable Audio cable 1 4 miniplug to dual RCA Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 2 1 Technical Overview AV Device Features The AV Device contains a number of features that offer you considerable flexibility for measuring a variety of auditory and visual stimuli Figure 1 1 shows the AV Device 1 2 3 E 9 oO Power DIN DIN2 DIN3 Isolated E Outputs 400 UN NE AN Tester Electrical Geodesics Inc 541 687 7962 USA Inputs i Photocell Audio Chart Figure 1 1 The AV Device The following are brief descriptions of the numbered items from Figure 1 1 1 9 VDC port Provides a receptacle for the plug of the power supply cable The other end of the power supply cable connects to a surge suppressed power socket in the experiment room 22 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 1 Technical Overview 2 DINs Output port Provides digital output with the choice of three duration values which are described in the next section entitled DIN Specifics The DINs Output port is connected to a DIN port on the amplifier via the DIN patch cable 9 Light emitting diode LED lights Indicate power on and DIN activity 4 Isolated Outputs ports Provide receptacles for low level 400 uV and high level 2 V analog outputs
48. n Black on CRT and LCD Monitors White stimuli that appear on a black background are not a problem for either CRT or LCD monitors in the timing sense they appear onscreen almost instantaneously and phosphor decay is not an issue black background is therefore the preferred visual stimulus testing mode Black on White on CRT and LCD Monitors Black stimuli that appear on a white background are a problem for most CRT monitors precisely because of phosphor decay i e the fact that pixels are slow to turn off from full brightness In testing at EGI we ve discovered that as a consequence of this battery effect black on white stimuli can be delayed by as much as 80 milliseconds Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 5 Troubleshooting The photocell still reports the actual time at which the monitor dims beyond threshold but the ECC reports when the event begins to happen As far as the ECC is concerned the event does happen earlier it s the built up energy in the pixel that causes an unexpected delay However because there is no clock drift involved in the white to black error only a constant time offset ERPs can still be cleanly averaged in spite of the CRT monitor error see Time Offset on page 62 Researchers should note however that their EEG may lag the supposed causal event by as much as 80 milliseconds or more for black on white stimuli Subject responses may lag as well which raises th
49. nformation that if unheeded could hinder use of the product or result in injury or equipment damage Troubleshooting and Support Chapter 5 Troubleshooting is a ems troubleshooting guide SS nnn n Bel sin e For online updates to this book check 5 Documentation page at www egi com documentation html e For AV Device technical support see Appendix A Technical Support 1111111 101111011 The Documentation page at www egi com documentation html Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 TECHNICAL OVERVIEW he Audio Visual AV Device from Electrical Geodesics Inc EGI is designed to work with EGI Geodesic EEG Systems GES that are configured to operate with experiment control systems to conduct event related potential ERP studies The AV Device can be used for two purposes e To verify that the system timing is correct To verify that an E Prime experiment is programmed correctly The topics covered in this chapter include when to use the AV Device an overview of AV Device operations the AV Device package AV Device features basic event timing theory and the effect of miscorrelation When to Use the AV Device The AV Device is designed for use by both EGI personnel and customers in the following cases e Before a GES is shipped with an experiment control setup EGI uses th
50. ollowing Check that the Net Amps is on 5 f using a Net Amps 200 check that the power indicator on the front panel is brightly lit Some Net Amps 200 models have a two stage indicator The light is dim if the amplifier is plugged in and bright if the Net Amps 200 is on e Check that the AV Device s LEDs illuminate properly according to the stimulus you are using e g for an auditory stimulus the DIN 2 LED should illuminate e Check that the AV Device is connected to the Net Amps via the DIN patch cable e Check that the Events button is selected in the Net Station Viewer and that the Events control strip is visible Check that the desired DIN is selected as an event in the Setup Single Channel Input window of the Digital Input Controls panel e f you are testing black stimuli on a white background make sure you have selected the TTL button in the Source tabpanel of the Digital Input Controls panel If these tests succeed and the DIN events are still not visible in Net Station contact EGI Technical Support Appendix A 64 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 5 Troubleshooting Visual Stimuli This section discusses the effects of monitor refresh rates and phosphor decay on the presentation of visual stimuli Refresh Rates of CRT and LCD Monitors The refresh rate is the number of times per second a monitor is illuminated CRT monitors are inconstant displays By repeatedly
51. presenting auditory or visual stimuli via a screen or speakers and for establishing or controlling stimulus timing The ECC communicates timing information by way of a serial or an Ethernet cable to the DAC Net Station registers the data as Experimental Control Interface ECI events A cable connects the AV Device and the Net Amps amplifier which transmits the AV Device outputs to the DAC which is responsible for recording the EEG data along with the incoming event stream Net Station registers the AV Device outputs as DIN events and the E Prime event information as ECI events in the Events control strip Figure 1 3 HAE gt even eyec bade bads comm moto neis ECI TCP IP 55513 Figure 1 3 ECI and DIN events in Net Station s Events control strip For more information about data acquisition and experiment control see the Net Station Acquisition Technical Manual GES Hardware Technical Manual E Prime Extensions for Net Station User Manual or E Prime Biological Add ons for Net Station User Manual Miscorrelation EEG data and ECI and DIN events are indexed with respect to time an essential feature if the ERPs are to be correctly associated with their causal stimuli Errors in the indexing of either the EEG or the event stream result in miscorrelation between stimulus and EEG Clock drift time offsets and programming errors are three causes of miscorrelation
52. put state change Further details can be found in the Net Station Acquisition Technical Manual and the GES Hardware Technical Manual drift The change in a signal s offset over time or the amount by which a signal s offset changes with time ECI See Experimental Control Interface EEG electroencephalography The science of graphically recording the electrical activity of the brain as recorded by an electroencephalograph electroencephalography The science of recording and analyzing the electrical activity of the brain ERP See event related potential event discrete occurrence that coincides with EEG An event could be a DIN or ECI event or some other Net Station occurrence Further details can be found in the Net Station Acquisition Technical Manual event related potential An EEG waveform elicited by a stimulus such as an auditory or visual event Audio Visual Device Technical Manual Experimental Control Interface Built into Net Station is a protocol for experimental control technology that uses the Multi Port ECI device along with a messaging system G geodesic The shortest distance between two points on the surface of a sphere The Geodesic Sensor Net is a structure of elastomer lines in the approximation of a geodesic Geodesic Sensor Net EGI s dense sensor array GSN See Geodesic Sensor Net H Hertz Cycles per second Something that occurs with a frequency of 10 Hertz happens 10 times each s
53. rectly Following are some guidelines to interpreting the Event Timing Tester results e Ifthe Offset values steadily increase or decrease this is a sign of clock drift You can correct this by using the clock synch approach a clock scaling factor or EGI s single clock solution for more information see Clock Drift on page 59 e If the Offset values are constant this is a sign of time offsets Time offsets are to be expected because of hardware delay and other factors You can correct this by entering the average offset value into the Offset textbox when creating a Segmentation specification for segmenting your data for more information see Time Offset on page 62 e If the Offset values are variable sometimes referred to as jitter this is a sign of a hardware error e g a poorly functioning sound card testing error or more likely a programming error in E Prime 5 For information about likely hardware errors contact EGI Technical Support Appendix A 5 For information about testing errors see Chapter 5 Troubleshooting For information about programming errors see Chapter 3 Critical Timing in E Prime in the E Prime User s Guide which is available from PST www pstnet com Clock Drift Any clock is an approximation of real time and continuously drifts away from synchronization with that real time This limitation can apply to the interaction between the DAC and the ECC Each computer
54. related ECI events V vertex The point on an EEG subject s scalp that is closest to the top of the head In the International 10 20 system Cz is the vertex electrode In the Adult 128 GSN electrode 129 is the vertex The point on the scalp or skull located midway between the nasion and inion and centered between the preauricular points Also the name of the Geodesic Audio Visual Device Technical Manual Sensor Net sensor that corresponds to this location and that contains the reference electrode volt voltage A measure of electrical force or the tendency for electrons to move from one location to another Voltages are measured with respect to a reference W Workbench The Net Station equivalent of an electronics laboratory On the Workbench modular device are connected by data cables into Workbench configurations of differing functionality See Acquisition Setup file S MAN 200 AV 001 e May 7 2007 Audio Visual Device Technical Manual audio cable for AV Device 1 auditory stimuli DIN selection for 36 auditory stimulus testing AV Device setup 49 basic experiment requirements 45 configuring Net Station 50 connecting the audio cable 48 connecting the AV Device 46 ECI and DIN events in the Events control strip of the Dense Waveform Display 52 hardware configuration 46 test instructions 52 verifying AV Device functionality 51 verifying receipt display of DIN 50 AV Device 9 VDC port 22 audio cable 1 carr
55. rs in an experiment Both are described in more detail on page 59 and page 62 A timing error may also be caused by incorrect programming of the experiment For more information about programming errors see Chapter 3 Critical Timing in E Prime in the E Prime User s Guide www pstnet com Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 1 Technical Overview AV Device Package The AV Device is an option to the GES The complete AV Device package includes e AV Device e carrying case photocell e photocell holder supplied in two pieces base and stem e digital input DIN patch cable power supply cable e audio cable 1 4 miniplug to dual RCA e Event Timing Tester drag and drop analysis software described in Chapter 4 located in the Net Station Extras folder e Audio Visual Device Technical Manual Table 1 1 shows the hardware components of the AV Device package Table 1 1 AV Device package hardware Carrying case containing all the hardware Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 19 1 Technical Overview Table 1 1 AV Device package hardware AV Device Fear Bi D4M2 Dani EET T il AV Tester e Elena pen 341 887 1982 inputs Photocell Photocell holder assembled Stem Base 20 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 1 Technical Overview Tab
56. s the Event Timing Tester analysis software which allows you to evaluate the results of the auditory or visual timing tests The Event Timing Tester produces a file that compares the offsets between Net Amps digital input DIN and Net Station Experimental Control Interface ECI events and allows you to determine the precision of the stimuli presentation The chapter offers solutions to issues such as clock drift time offsets and other timing errors e Troubleshooting Chapter 5 Troubleshooting describes common AV Device problems and solutions For further assistance with the AV Device please contact EGI Technical Support Appendix A Audio Visual Device Technical Manual S MAN 200 AV 001 e May 7 2007 XV Conventions Typography e In this manual the following are treated as synonyms Audio Visual Device and AV Device e Older versions of the device may be labeled AV Tester however because of regulatory concerns the manual refers to the device as the AV Device In general a minimal amount of special fonts are used in this manual italics for definitions or newly introduced terms boldface italics for important concepts and boldface for command paths such as File gt Save Additional Information Two different methods are used to convey additional information notes and cautions Note This indicates information that is helpful in understanding AV Device operations Caution This denotes important i
57. sing the Net Amps 300 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 47 3 Auditory Stimulus Testing Connecting the Audio Cable The audio cable must be connected to a high level audio output because low level signals will not trigger the AV Device reliably The best method is to connect the miniplug end of the audio cable to the headphone miniplug port on the back of the ECC Figure 3 2 Depending on the laboratory setup you may need to use a 1 4 miniplug extension cord male to female to connect the audio cable and the ECC Note Because computer upgrades may change the location of the audio port contact EGI Technical Support Appendix A if you have difficulty locating this port Headphone port Figure 3 2 The audio cable plugged into the miniplug port on the back of the ECC 48 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 3 Auditory Stimulus Testing The finished setup is shown in Figure 3 3 GES setup Monitor USB or Data acquisition FireWi bl t QU Amplifier SE pile CH phe unning 6 Power S socket DIN port S 4 DIN patch Adapter cable cable d Adapter for Net Amps 300 ae Die SSS Ss SS SS EE ee SS SS SS SS ECC setup Stimulus ten Experimenter s presentation monitor monitor O O Q
58. tation Acquisition is the component of the Net Station software for acquiring EEG in conjunction with the dense array Geodesic Sensor Nets The Net Station Acquisition Technical Manual provides comprehensive descriptions of all Acquisition features and functions The NetStation Viewer is the component of Net Station for viewing and navigating EEG data The Net Station Viewer Technical Manual provides comprehensive descriptions of all Viewer features and functions e The Net Station Waveform Tools is the component of Net Station for performing various operations on EEG data The Net Station Waveform Tools Technical Manual provides comprehensive descriptions of all Waveform Tools features and functions e The Net Station Viewer and Waveform Tools Tutorial instructs you in the use of Net Station Viewer and Waveform Tools by guiding you through the analysis of a sample data set It is not intended to be a comprehensive guide to these components but it is a good place to start when learning about the software The Net Station File Formats Technical Manual documents the objects contained in a native Net Station file the formats of the export files and other files associated with Net Station These publications contain a good deal of background information on the EEG ERP field However they are not intended to represent a complete primer To get the most out of these manuals you should have some background in EEG ERP met
59. the beginning of the sound Very slow volume ramp ups may not trigger the AV Device at stimulus onset Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 45 3 Auditory Stimulus Testing e Compatible audio source The audio source must be compatible with RCA miniplug or 1 inch headphone connections If the experiment lacks some or all of these features it may still be testable in a modified form Contact EGI Technical Support for assistance Appendix A Hardware Configuration You will need the following e AV Device with power supply cord DIN patch cable and audio cable 1 4 miniplug to dual RCA aGES ECC setup Note It is important to use the provided audio cable because it includes a built in attenuator for compatibility with the AV Device The GES and ECC setup shown in Figure 1 2 on page 25 is the two machine configuration that is normally used for stimulus presentation and data collection Note During timing tests the GSN typically is not connected to the amplifier The GES and ECC setups for an auditory stimulus test are similar to those for a visual stimulus test except the ECC setup contains speakers or other audio source For details see GES Configuration and ECC Configuration on page 30 Connecting the AV Device To connect the AV Device you will use the provided cabling to connect the device to the amplifier a power socket and the audio output See Table 1 1 on page 19 and Figure 1
60. trip of the Dense Waveform Display Figure 2 11 File Edit Dots Took Acq Panels Record Met Time Amplitude Events d Thu 51AM 125 bitte Recording oa Waveform Display m mia aramis e DE res eer DIN and Jee 030 0 ma en m e m m we ME c ECI events b Time DO Multi Port IO 1000091 TEPP bat 55517 Canare To PC gmo danrription H 89 5 00 0 5 AE HU 0 5 9 9 0 0 0 5 8 9 5 0 9 NEU Figure 2 11 Visual ECI and DIN events in the Events control strip of the Dense Waveform Display 4 If DINs appear when the stimulus is off make sure you have the correct DIN selected for the stimulus duration in the Setup Single Channel Input window see page 35 5 Complete the experiment and press Return to exit when prompted to do so 6 Exit NetStation which will automatically save the timing results file as a Net Station Recording 42 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 2 Visual Stimulus Testing Viewing the Results To view the results launch the Event Timing Tester program and open the Net Station timing results file For information about how to use the Event Timing Tester see Chapter 4 Audio Visual Device Technical Manual S MAN AV 001 e May 7 2
61. ual S MAN AV 001 May 7 2007 chapter 2 VISUAL STIMULUS TESTING his chapter describes how to test the precision of visual stimulus presentation using the AV Device The topics covered in this chapter include general considerations such as basic experiment requirements hardware configuration positioning the photocell holder which involves configuring the software verifying AV Device functionality and test instructions General Considerations The EGI E Prime timing test meets all the testing requirements If you are testing the timing of your own E Prime visual stimulus experiment the experiment must have the following features Identical setup If possible we recommend using the actual experiment If this is not possible then the experiment should be as similar as possible to the actual experiment in particular stimulus type and size GES and ECC configurations and software versions should be identical e Full duration If possible we recommend using the actual experiment If this is not possible then the duration number of trials and blocks of trials should be as the experiment will be used Timing errors accumulate testing a short version of an experiment does not certify a longer version Same location The visual stimulus must always appear in the same location If they do not you can run the test multiple times to account for the different locations Audio Visual Device Technical Manual S
62. ulation presentation monitor for the subject e computer peripherals such as a keyboard and a mouse e external stimuli equipment such as speakers for auditory experiments e a subject response pad e required cabling Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 1 Technical Overview Figure 1 2 shows the two system setup for ERP studies with all the components included During timing tests the GSN typically is not connected to the amplifier GES setup Monitor GSN interface cable E USB or FireWire Data acquisition connector cable computer running Net Station Amplifier DIN port DAC serial or Ethernet port response pad Subject response pad optional gt O css uc cS MS ee zi ECC setup e 2 zi Stimulus p i 5 Experimenter s presentation monitor monitor ES ECC serial Speakers or Ethernet optional port _ Experiment control computer running serial response an experimen box 0O Keyboard m Subject Figure 1 2 Experiment control diagram Audio Visual Device Technical Manual S MAN AV 001 e May 7 2007 25 1 Technical Overview 26 System Overview The ECC is responsible for
63. ying case 19 device 20 DIN patch cable 21 DINs Output port 23 Inputs ports 23 Isolated Outputs ports 23 LED lights 23 operational overview 18 package components 19 photocell 20 photocell holder assembled 20 power supply cable 21 uses 17 S MAN 200 AV 001 e May 7 2007 using with other experiment control setups and software 18 basic experiment requirements auditory stimulus testing 45 visual stimulus testing 29 black stimuli problem of 66 carrying case for AV Device 19 clock drift 59 clock synch 61 clock scaling factor 61 configuration of Net Station auditory stimulus testing 50 visual stimulus testing 34 configuring DINs using the Setup Single Channel Input window of Net Station 35 connecting the audio cable for auditory stimulus testing 48 connecting the AV Device auditory stimulus testing 46 visual stimulus testing 32 D Dense Waveform Display panel of Net Station 36 digital input DIN events 26 29 Digital Input Controls panel of Net Station 5 DIN 1 selection of 36 DIN 2 selection of 36 DIN 3 selection of 36 DIN patch cable for AV Device 21 DIN selection for duration and stimuli type 23 DINs always lit 64 DINs fail to illuminate 63 DINs not visible in Net Station 64 DINs Output port of AV Device 23 duration values of AV Device digital output 23 ECC system configuration 24 purpose 26 ECI and DIN events in Net Station s Events control strip 26 EGI E Prime timing fil
64. your ECC or contact EGI Technical Support Appendix A Overview of AV Device Operations In conjunction with a GES running Net Station acquisition review and analysis software and an ECC system the AV Device acquires timing data from ERP studies to measure the timing accuracy of the presentation of the stimuli Note This manual describes how to use the AV Device with a GES and an EGI ECC running E Prime However the device can be used with other experiment control setups and software for more information contact EGI Technical Support Appendix A The AV Device determines accuracy by providing a second external measure of stimulus onset or offset independent of the timing reported by the ECC It does this by sensing an auditory or visual stimulus thresholding the analog data and passing the digital result to Net Station for storage and comparison with internal timing The Event Timing Tester drag and drop analysis software included with the Net Station package calculates the differences between the external and internal measures Any discrepancy between the two is a timing error timing error may be the result of clock drift or time offset in the presentation of the stimuli Clock drift occurs when a computer s internal clock drifts away from real time and from another computer s clock during the duration of an experiment Time offset is the delay between the time a stimulus is reported to have occurred and when it actually occu

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