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OPERATING INSTRUCTIONS AND SYSTEM DESCRIPTION FOR

1. operated by trained staff only General safety regulations for operating electrical devices should be followed AC MAINS CONNECTION While working with the npi systems always adhere to the appropriate safety measures for handling electronic devices Before using any device please read manuals and instructions carefully The device is to be operated only at 115 230 Volt 60 50 Hz AC Please check for appropriate line voltage before connecting any system to mains Always use a three wire line cord and a mains power plug with a protection contact connected to ground protective earth Before opening the cabinet unplug the instrument Unplug the instrument when replacing the fuse or changing line voltage Replace fuse only with an appropriate specified type STATIC ELECTRICITY Electronic equipment is sensitive to static discharges Some devices such as sensor inputs are equipped with very sensitive FET amplifiers which can be damaged by electrostatic charge and must therefore be handled with care Electrostatic discharge can be avoided by touching a grounded metal surface when changing or adjusting sensors Always turn power off when adding or removing modules connecting or disconnecting sensors headstages or other components from the instrument or 19 cabinet TEMPERATURE DRIFT WARM UP TIME All analog electronic systems are sensitive to temperature changes Therefore all electronic instruments containing analog circuits should be use
2. ELECTRODE RESISTANCE test unit 10 The signals from the Vgi 10 and CURRENT OUTPUT BNCs 9 are monitored on an oscilloscope The SET OPERATE switch 12 must be in OPERATE position The CAPACITY COMPENSATION control 2 is turned on clockwise until the signal at the Vg 10 BNC is as square as possible see Figure 3 The highest speed is obtained with a small overshoot theoretically 4 3 96 The CAPACITY COMPENSATION control is based on the well known conventional compensation stray capacitances around the electrode are compensated by passing amounts of the electrode signal through a small capacitor The circuit is designed to minimize oscillations Caution As in any feedback circuit this circuit can cause overshoots or oscillations if it is overcompensated 7 2 Electrode Resistance Test Procedure MVCS C System MVCS C systems have an electrode resistance test unit built in It works by application of rectangular current pulses 10 nA to the electrode This will cause an voltage drop at the electrode which is proportional to the electrode resistance This voltage drop is measured the resulting electrode resistance calculated and shown at the digital display 4 L Set switch 12 to OPERATE _ Immerse the electrode into the bath and compensate for stray capacities see chapter 7 1 above Note If 12 is switched to SET the internal resistor of 10 MQ is measured and displayed If a different value is shown within
3. Tessier B Giannone G amp Choquet D 2008 Activity independent and subunit specific recruitment of functional AMPA receptors at neurexin neuroligin contacts Proc Natl Acad Sci U S A 105 20947 20952 Li Li Y Krupa B Kang J S Bolshakov V Y amp Liu G 2009 Glycine Site of NMDA Receptor Serves as a Spatiotemporal Detector of Synaptic Activity Patterns J Neurophysiol 102 578 589 L Liu G Choi S and R W Tsien 1999 Variability of Neurotransmitter Concentration and Nonsaturation of Postsynaptic AMPA Receptors at Synapses in Hippocampal Cultures and Slices Neuron 22 395 409 L Murnick J G Dub G Krupa B and Liu G 2002 High resolution iontophoresis for single synapse stimulation J Neurosci Meth 116 65 75 LI M ller C Beck H Coulter D Remy S 2012 Inhibitory control of linear and supralinear dendritic excitation in CA1 pyramidal neurons Neuron 75 851 64 L Renger J J Egles C and G Liu 2001 A Developmental Switch in Neurotransmitter Flux Enhances Synaptic Efficacy by Affecting AMPA Receptor Activation Neuron 29 469 484 L Slutsky I Sadeghpour S Li B amp Liu G 2004 Enhancement of synaptic plasticity through chronically reduced Ca2 flux during uncorrelated activity Neuron 44 835 849 LI Tang Y P E Shimizu G R Dube C Rampon G A Kerchner M Zhuo G Liu and J Z Tsien 1999 Genetic enhancement of learning and memory in mice Nature 401 63
4. handled with care see also chapter 1 Very Important Always turn power off when connecting or disconnecting headstages from the 19 cabinet For changing electrodes it is sufficient to switch the respective channel to SET mode Also very important Each headstage is adjusted for a specific channel and instrument They are labeled A B C and D for the EJECT channels and COMP for the COMPENSATION channel Please do not exchange headstages for a respective instrument or between different MVCS instruments Systems for slow long lasting applications in the second or minute range need no headstages MVCS systems In these systems the electrodes are connected from special connectors on the front panel with shielded cables Pin 2 white blue wire ground Pin 5 yellow red wire electrode 6 Setting up the MVCS MVCS C System The following steps should help you set up the MVCS MVCS C system correctly Always adhere to the appropriate safety measures see chapter 1 After unpacking the MVCS MVCS C system is attached to the setup by assembling the electrical connections Electrical connections L Turn POWER off _ Plug the instrument into a grounded outlet L MVCS Connect your injection and COMPENSATION electrodes to the special connectors with shielded cables at the front panel Pin2 white blue wire ground Pin5 yellow red wire electrode MVCS C Connect the headstages to the HEADSTAGE connectors 13 Figure 1 at
5. the front panel LJ If the recording chamber is not grounded connect GND of the headstage MVCS C or GND 18 Figure 1 to the chamber Note System ground is isolated from mains ground The 19 cabinet is connected to mains ground headstage enclosures are connected to the internal system ground L MVCS C Connect the Vg 10O connectors to an oscilloscope or to a data acquisition system version 4 9 page 14 MVCS User Manual L If you intend to control the MVCS MVCS C system externally e g by a computer connect the gating waveform to TTL 15 Figure 1 the stimulus waveform to INPUT 11 Figure 1 and the current OUTPUT 9 Figure 1 to the analog input of the data acquisition system 7 Operation MVCS MVCS C systems are housed in standard 19 rackmount cabinets Each system is composed of two independent channels marked A and B and a COMPENSATION CHANNEL Each channel has an auxiliary analog input and an output that monitors the current flowing through the electrode Each channel is equipped with a digital display and two overload LEDs All numbered items refer to Figure 1 page 8 in the following discussion The Systems can be operated manually by means of a toggle switch on the front panel 16 or by an external digital pulse TTL connected to 15 L Turn CAPACITY COMPENSATION 2 for all channels to less than 1 to avoid oscillations Turn POWER on Set the operation mode of all channels to SET usin
6. 0 30 pF Output current polarity selected by INVERTED NORMAL toggle switch Modes of operation set by two toggle switches EJECT RETAIN AUTO switch enables manual or TTL controlled operation SET OPERATE switch connects automatically electrode outputs to ground SET position TTL input AUTO mode LO RETAIN HI EJECT isolated Rin gt 5 KQ Analog input sensitivity 100 nA V Rin 2100 KQO range 10 V Current monitor sensitivity 100 nA V Rou 50 Q not isolated Voltage monitor Vg 10 Rout 50 Q not isolated Balance output inverted sum of all injection currents sensitivity 1 uA V Power requirements 230 V 115 V 50 Hz 60 Hz AC 50W fuse 0 4A 0 8A slow Output connector pins and cable colors Pin2 white blue wire ground for systems without headstage Pin 5 yellow red wire electrode Dimensions Amplifier standard 19 rackmount cabinet 19 483 mm 10 250 mmy 3 5 88 mm Headstage approx 65x25x25 mm version 4 0 page 20
7. 21 INPUT 1p A V connector ys BNC connector for connecting an external voltage for using the COMPENSATION channel as an additional injection channel see also 19 Calibration is 1 uA V 22 OUTPUT Ip A V connector BNC connector providing a voltage proportional to the COMPENSATION current see also 9 This voltage can be used for monitoring the COMPENSATION current or for connecting to a second system see also 20 and 21 Calibration is 1 uA V aA version 4 9 page 12 MVCS User Manual 4 2 Rear Panel Elements POWER FUSE LINE VOLTAGE SELECTOR The power cord is connected by a standardized coupling which comprises also the fuse voltage selector and a line filter With 230V AC the fuse must be 0 4A slow with 115V AC it must be 0 8A slow Caution Always use a three wire line cord and a mains power plug with a protection contact connected to ground Before opening the cabinet unplug the instrument Unplug the instrument also when replacing the fuse or changing line voltage Replace fuse only by appropriate specified type see also chapter 1 GROUND PROTECTIVE EARTH CONNECTORS In order to avoid ground loops the internal zero ground signal of the instrument is not connected to the mains ground and the cabinet The cabinet and mains ground are connected to the green yellow connector the internal ground is connected to the yellow connector See also GND connector chapter 4 1 and chapter 5 5 Heads
8. 69 version 4 0 page 18 MVCS User Manual General methods L Lalley P M 1999 Microiontophoresis and Pressure Ejection in U Windhorst and H Johansson eds Modern Techniques in Neuroscience Research Springer Berlin Heidelberg New York highly recommended _ Ogden D ed 1994 Microelectrode Techniques The Company of Biologists LTD Cambridge L Purves R D 1981 Microelectrode Methods for Intracellular Recording and Iontophoresis London Academic Press L Roberts M H T and T Gould 1993 Iontophoresis in the mammalian central nervous system in D I Wallis ed Electrophysiology A Practical Approach Oxford University Press Oxford L Zieglg nsberger W 1992 Arrays for Microiontophoresis in Kettenmann H amp Grantyn R eds Practical Electrophysiological Methods Wiley Liss New York version 4 0 page 19 MVCS User Manual 9 Technical Data Electrode output floating current source output impedance 10 Q Maximum current 450 nA 1 5 uA into 100 MQ load Display current XXXX nA balance XX XX uA voltage XXX X V Ra XXXX MQ displayed value is set by a three position toggle switch separate displays for each channel Over LEDs activated 1096 below maximum current voltage Eject ten turn control range 100 nA or 1 uA selected by switch Minimum pulse duration 100 us Retain ten turn control maximum 100 nA Capacity compensation ten turn control range
9. 7 modular system The standard system described here is housed in a 19 rackmount cabinet The MVCS 02C consists of two independent channels for current ejection and the other COMPENSATION is for balancing the applied current automatically Each ejection channel has digital ten turn potentiometer for EJECT or RETAINING currents and CAPACITY COMPENSATION Each injection channel also has a digital display overrange LEDs and two switches for selection of the operating mode The COMPENSATION channel has the same controls but no potentiometer for adjusting current In fast systems with CAPACITY COMPENSATION MVCS C the injecting electrodes are connected via small SMB or BNC shielded connectors that are mounted to a small headstage avoiding artifacts caused by long cables Systems for slow long lasting applications in the second or minute range MVCS need no headstages In this case the electrodes are connected by special connectors at the front panel with shielded cables For EJECT or RETAIN currents modes of operation include manual activation and automatic control by digital TTL signals HI EJECT LO RETAIN An automated electrode resistance test mode MVCS C is also available 3 1 Compensation Balance Unit To avoid artifacts caused by iontophoretic drug application the MVCS 02C systems are available with a compensation unit built in The compensation signal inverted sum of current output signals divided by 10 generated intern
10. Electronic Instruments for the Life Sciences pease wade OPERATING INSTRUCTIONS AND SYSTEM DESCRIPTION FOR THE MVCS Series IONTOPHORESIS SYSTEMS With Fast Capacitance Compensation 003 CO 66 6 6 5 Os 5 NN oT is 9 9 O exo NS o _ NC er M MVCS 02C Without Fast Capacitance Compensation I Wu MVCS 02C npi Pa amp i e A an A Two ie oi O VERSION 4 9 npi 2013 npi electronic GmbH Bauhofring 16 D 71732 Tamm Germany Phone 49 0 7141 9730230 Fax 49 0 7141 9730240 support npielectronic com http www npielectronic com MVCS User Manual Table of Contents ADOS this NERA son E echte rst en ante Goeaetees a oo veathcaeencogedaacadagexaetenaenaaees a A NR 3 lo Safety ReoHlat Hs nennen best eMe R an tiM ce e Doe NN NE 4 2 MVO S k SOMONE AS didi ee ER Ob tre sei Se esau ae vnc teme een dee 5 Sco sten Dese DL ose uot uisa ed ahis UK aa as ces mE DEDE od E 3 3 1 Compensation Balance Unit ueber ea ceases ui Ice SUE AUO EE eC UR 6 3 2 Fast Capacitance Compensation MVCS C System sse 6 3 3 Electrode Resistance Test MV CS C System esesseseseeeeeeeeenee enne 7 Electrode resistance test for EJECT channels sese 7 Electrode resistance test for COMPENSATE channel eene 7 4 Description or the Front Patel ees Get ue He tale aciei en ua dd e Uu e aN 8 4 T Front Panel Blenietitsa2s o Moe eR ced
11. a tolerance of 10 it is likely the amplifier or the headstage is damaged Please contact npi electronic in this case L Set Vg Ig Rer switch to Rey The resistance of the electrode is shown at display 4 Important The electrode resistance is displayed correctly only if the electrode capacity is compensated accurately Note The electrode resistance test is functional also if a iontophoresis current is generated This feature can be used to test the resistance at different current levels For testing rectification the EJECT potentiometer or a ramp signal at the INPUT connector can be used for setting a current level Testing of rectification of the electrode is done e g by application of different current levels both positive and negative to the electrode using the EJECT potentiometer and testing the resistance of the electrode If the resistance changes at a certain level the electrode rectifies and should not be used for application of currents above or below this level i e the resistance must not change over the range of current which is used during the experiment version 4 0 page 16 MVCS User Manual undercompensated potential mV 250 0 10 20 30 40 50 time ms overcompensated potential mV 600 400 200 o 200 400 600 0 10 20 30 40 50 time ms compensated potential mV 250 200 190 100 50 10 20 30 40 50 time ms potentia
12. ally is applied to a separate compensation electrode if the OPERATE mode is selected for the injection channel s and COMPENSATE mode is selected for the COMPENSATION channel 3 2 Fast Capacitance Compensation MVCS C System The MVCS C iontophoresis instruments have been designed for high speed application of drugs in electrophysiological experiments In addition to the standard features of the slow MVCS devices each channel has a capacity compensation circuit and an Reg test unit see chapter 3 3 The capacity compensation circuit is operated by the control marked CAPACITY COMPENSATION The correct tuning of the capacity compensation is very important if high speed operation in conjunction with high resistance microelectrodes is required Uncompensated stray capacitances are charged from the iontophoretic current that is supplied by the instrument Uncompensated stray capacitance therefore slows application The tuning procedure is described in chapter 7 1 The CAPACITY COMPENSATION control is based on the well known conventional compensation stray capacitances around the electrode are compensated by passing amounts of the electrode signal through a small capacitor The circuit is set so that overshoots are avoided as far as possible Caution Just like any feedback circuit this circuit can cause overshoots or oscillations if it is overcompensated version 4 9 page 6 MVCS User Manual 3 3 Electrode Resistance Test MVCS C S
13. d only in a warmed up condition i e after internal temperature has reached steady state values In most cases a warm up period of 20 30 minutes is sufficient HANDLING Please protect the device from moisture heat radiation and corrosive chemicals CURRENT INJECTION HIGH VOLTAGE HEADSTAGE The current injection headstages have an output compliance of 45 V up to 150 V In addition some headstages are equipped with a driven shield electrode connector marked Driven Shield on the headstage enclosure After turning on the instrument do not touch the interior contact or the shield of the electrode plug or of the cable that is connected to this plug In addition it is extremely important that the instrument is turned off when changing or adjusting the electrode version 4 9 page 4 MVCS User Manual 2 MVCS Components The following items are shipped with a MVCS system MVCS amplifier Headstage MVCS C systems only GND connector for headstage 2 6 mm MVCS C systems only Electrode cables slow MVCS systems only Power cord User manual SSSASSAS Optional accessories Electrode holder Electrode adapter with BNC connectors elec e e aaaprer 3 System Description MVCS systems are high voltage current sources for iontophoresis or other applications where constant currents in the nano or microampere range are needed Standard MVCS 02C systems have an output compliance of 45 V and can generate current
14. e electrode is displayed L In OFF mode the resistance inside the headstage 10 MQ is monitored Important The CAPACITY COMPENSATION unit must be tuned properly see chapter 7 1 Otherwise the electrode resistance display may be inaccurate Tuning capacity compensation can also be done using the pulses of the electrode resistance test version 4 0 page 7 MVCS User Manual 4 Description of the Front Panel COMPENSATION CHANNEL CHANNEL B CHANNEL A Figure 1 MVCS C 02C front panel view the numbers are related to those in the text below version 4 9 page 8 MVCS User Manual 4 1 Front Panel Elements In the following description of the front panel elements each element has a number that is related to that in Figure 1 The number is followed by the name in uppercase letters written on the front panel and the type of the element in lowercase letters Then a short description of the element is given The front panel can be divided into three functional units CHANNEL A CHANNEL B and COMPENSATION CHANNEL Most of the elements are identical for each unit with identical functions and labels and therefore are numbered and described only once e g 12 HEADSTAGE connector that is also present for CHANNEL B and the COMPENSATION CHANNEL Figure 1 shows the MCVS C 02C fast system with capacity compensation and the automatic electrode resistance test facility These two features are not present in t
15. g switch 12 to disable current output Set the EJECT and or RETAIN current amplitude to the desired values using 7 and 17 O O vu MVCS C First compensate the stray capacitances of the electrodes see chapter 7 1 and second check the electrode resistances by switching 10 to Rgr see also chapter 3 3 and 7 2 Important The values of the ELECTRODE RESISTANCE are accurate only if the capacitances of the electrodes are compensated properly _ Put the injection and compensation electrodes to the desired position L Start iontophoresis either manually by setting switch 16 to EJECT and switch 12 to OPERATE or remotely by setting switch 16 to AUTO and applying a TTL pulse to 15 7 1 Capacity Compensation Tuning Procedure MVCS C System The tuning of the capacity compensation controls is performed with the help of the electrode potential monitor BNC marked Vgj 10 8 and square pulses applied to the electrode This pulse can originate from the built in ELECTRODE RESISTANCE TEST circuit or from an external signal source The pulses generated internally by the ELECTRODE RESISTANCE test unit have an amplitude of 10 nA version 4 9 page 15 MVCS User Manual The tuning must be performed with the electrode in the bath immersed to the maximal depth required during the experiment Square pulses positive and negative of a few nA and 0 1 10 ms duration are applied to one of the INPUT BNCs 11 or by activating the
16. he MVCS 02C slow system In the slow system the CAPACITY COMPENSATION potentiometer is not installed and the function of Rg is somewhat different see below 1 POWER switch OH Switch to turn POWER on switch pushed or off switch released POWER 2 CAPACITY COMPENSATION potentiometer Ten turn control to set amount of compensation of electrode stray capacitance see also chapter 7 1 3 V nA MQ LEDs LEDs indicating the unit of the reading of the DISPLAY 4 4 CHANNEL A display 3 1 2 digit display for the electrode potential in V XXX X V the electrode curent in nA XXXX nA for channels A and B XX XX uA for P COMPENSATION channel or the electrode resistance in MO XXXX MQ i e 0100 correspond to 100 MQ selected by toggle switch 10 For the correct value of the electrode resistance display it is necessary to adjust the capacity compensation accurately see chapter 7 1 version 4 0 page 9 MVCS User Manual 5 OVER LEDS LEDs indicating that the current source is out of linear range or that the EET LEER electrode voltage current is 1096 below the maximum output voltage current 6 1 uA 100 nA switch LJ TON Two position switch to select the range of the eject current maximal 1 uA or maximal 100 nA 7 EJECT potentiometer e Ten turn control to set the EJECT current The maximal EJECT current is selected by switch 6 8 Vg 10 connector BNC connector m
17. i ausu a Nutt a uaa a cde due 9 COMPENSATION Channel Optional eese esee seen eene nnnnn 12 4 2 Rear Panel Elerents eser ESSA URWRR RN A SAU SERVITAQNA IR RES ERN 3E ADET 13 2 Headstqse MV CSC S SIG sos ecocch t ae tote e e a sese y o ocean odi dee tse dei vet 13 6 Setting up the MVCS MVCS C System esee ise tei ER OO PCIe Rep eee ERR e Re Lee dara RUE 14 T Operations siete Datuk ences ardt a a a aca hies tues a A ands optat cu as 15 7 1 Capacity Compensation Tuning Procedure MVCS C System sess 15 7 2 Electrode Resistance Test Procedure MVCS C System sees 16 B Literature meen aa tendo Duende ossi iu axem tes in6as e e ct eu athe 18 9 Technical Dados are a dea PN ONU ned caede cereal gaa Pe a bee 20 version 4 0 page 2 MVCS User Manual About this Manual This manual should help you setup and use the MVCS 02C system correctly and to perform accurate experiments Generally two different versions of the MVCS 02C system are available e System without headstage Rg test and CAPACITY COMPENSATION MVCS 02C versions e System with headstage Rg test and CAPACITY COMPENSATION MVCS C 02C versions Note In this manual the slow MVCS 02C version is referred as MVCS whereas the fast MVCS C 02C version is referred as MVCS C If you are not familiar with the use of instruments for iontophoretic application of substances please read the manual comp
18. l Figure 3 Capacity compensation of the electrode version 4 9 page 17 MVCS User Manual 8 Literature Iontophoresis and drug application during single electrode voltage clamp experiments L Richter D W Pierrefiche O Lalley P M and H R Polder 1996 Voltage clamp analysis of neurons within deep layers of the brain J Neurosci Methods 67 121 131 Iontophoretic labeling of cells L Varvel NH Grathwohl SA Baumann F Liebig C Bosch A Brawek B Thal DR Charo IF Heppner FL Aguzzi A Garaschuk O Ransohoff RM Jucker M 2012 Microglial repopulation model reveals a robust homeostatic process for replacing CNS myeloid cells Proc Natl Acad Sci U S A 109 18150 5 Fast capacity compensation Simulation of synaptic events L Behrends J C Lambert J D C and K Jensen 2002 Repetitive activation of postsynaptic GABAA receptors by rapid focal agonist application onto intact rat striatal neurones in vitro Pfl gers Arch 443 707 712 L Cottrell J R Dube G R Egles C and G Liu 2000 Distribution Density and Clustering of Functional Glutamate Receptors Before and After Synaptogenesis in Hippocampal Neurons J Neurophysiol 84 1573 1587 LI Heine M Groc L Frischknecht R Beique J C Lounis B Rumbaugh G Huganir R L Cognet L amp Choquet D 2008 Surface mobility of postsynaptic AMPARs tunes synaptic transmission Science 320 201 205 L Heine M Thoumine O Mondin M
19. letely The experienced user should read at least chapters 1 4 and 5 Important Please read chapter 1 carefully It contains general information about safety regulations and how to handle highly sensitive electronic instruments Signs and conventions In this manual names of all elements of the front panel are written in capital letters as they appear on the front panel System components that are shipped in the standard configuration are marked with V optional components with In some chapters the user is guided step by step through a certain procedure These steps are marked with h Important information hints and special precautions are highlighted in gray Abbreviations Ig current at electrode Ret electrode resistance VeL voltage at electrode version 4 0 page 3 MVCS User Manual 1 Safety Regulations VERY IMPORTANT Instruments and components supplied by npi electronic are NOT intended for clinical use or medical purposes e g for diagnosis or treatment of humans or for any other life supporting system npi electronic disclaims any warranties for such purpose Equipment supplied by npi electronic must be operated only by selected trained and adequately instructed personnel For details please consult the GENERAL TERMS OF DELIVERY AND CONDITIONS OF BUSINESS of npi electronic D 71732 Tamm Germany 1 2 3 4 5 6 GENERAL This system is designed for use in scientific laboratories and must be
20. onitoring the electrode potential divided by 10 Normally used to EE monitor the electrode resistance see also chapters 3 3 and 7 1 9 OUTPUT 100 nA V connector 5 BNC connector monitoring the EJECT or RETAIN current LJ Calibration for channels A and B 100 nA V Calibration for the COMPENSATION channel 1 uA V The OUTPUT is not isolated from system ground om 10 Ver Ig Re switch wm position toggle switch to set the mode of display CHANNEL A 4 Ok Position Vg the electrode potential is displayed Position Igy the current flowing through the electrode is displayed Position Rer the electrode resistance is displayed Rez is obtained by application of current pulses of 10 nA to the electrode Important The Re mode is an option that is only implemented in MVCS C fast systems In MVCS slow systems the Rg position of the switch has the same function as the Ig position middle position 11 21 INPUT connector BNC connector for an auxiliary INPUT This BNC is directly connected to the E output current source and is not isolated from ground Calibration for channels A and B 100 nA V Calibration for the COMPENSATION channel 21 1 nA V Mr Note The COMPENSATION channel can be used as an additional injection channel by linking an external waveform to this connector and setting switch 19 to EXTERN version 4 0 page 10 MVCS User Manual 12 SET OPERATE switch Em Two position s
21. s up to 450 nA into 100 MQ while high voltage MVCS systems work with up to 150 V generating currents up to 1 5 uA into 100 MO MVCS system are available with one or two ejection channels A one channel version can be upgraded to a second ejection channel or to an additional compensation balance channel see below The two channel systems are also available with or without a balance channel Generally two different versions of MVCS system can be ordered e System without headstage Rg test and CAPACITY COMPENSATION MVCS 01C or MVCS 02C and MVCS 01 or MVCS 02 versions e Systems with headstage Re test and CAPACITY COMPENSATION MVCS C 01C or MVCS C 02C and MVCS C 01 or MVCS C 02 versions Note In this manual the respective two channel version is described The slow MVCS 02C and MVCS 02 versions are referred as MVCS whereas the fast MVCS C 02C version is referred as MVCS C The operating and display elements of these instruments facilitate the application of drugs in physiological pharmacological and biochemical studies All systems allow very fast drug applications in the millisecond range and even the sub millisecond range if equipped with the fast capacitance compensation option Therefore these systems can be used to simulate synaptic events Renger et al 2001 Cottrell et al 2000 Liu et al 1999 version 4 0 page 5 MVCS User Manual The MVCS systems are available as 19 instruments or as modules for the EPMS 0
22. tage MVCS C System The headstage is housed in a small box that can be mounted directly onto a micromanipulator It is connected to the main amplifier by means of a shielded flexible cable and a multi pole connector electrode holder headstage optional AN IONTOPHORESIS HEADSTAGE tap eera N COMP OPERATE Figure 2 MVCS C 02C headstage for channel A 1 Pet BNC connector for the electrode holder grounded shield 2 CHANNEL indicator marker show for which CHANNEL the headstage is configured in the example shown for CHANNEL A see also hint below 3 OPERATE LED indicates that injection takes place 4 GND ground connector 5 holding bar and headstage cable to amplifier mounting plate or dovetail on request GND GROUND connector The bath or reference of the recording chamber is connected to GND This is the lowest signal level in the recording system i e all signals are related to this signal This connector must be connected to the ground signal of the recording amplifier chamber version 4 9 page 13 MVCS User Manual PEL In order to avoid disturbances on the recording amplifier the microelectrode holder is connected via a BNC connector with a grounded shield Caution The current injection headstages have an output compliance of 45 V or 150 V In addition all headstages are equipped with very sensitive FET amplifiers that can be damaged with electrostatic charge and must therefore be
23. the headstage see chapter 5 o This ground is isolated from power ground PROTECTIVE EARTH see chapter 4 2 and the TTL INPUT ground version 4 9 page 11 MVCS User Manual COMPENSATION Channel Optional 19 COMPENSATE OFF EXTERN switch Switch to select the operation mode of the COMPENSATION channel COMPENSATE The inverted sum of channels A and B is applied to the electrode OFF No current is applied to the electrode EXTERN The output current source is connected directly to INPUT BNC 21 In this mode the COMPENSATION channel can be used as an additional injection channel If for example 1 V is connected at 21 an injection curent of lgA is applied to the electrode connected to the COMPENSATION channel 20 COMPENSATION INPUT d BNC connector for an additional COMPENSATION current This INPUT can be BS used to generate COMPENSATION current for two MVCS or MVCS C systems using only one compensation electrode Suppose one has two MVCS or MVCS C systems system 1 and system 2 The COMPENSATION OUTPUT 22 of the system 2 without compensation electrode can be fed into the COMPENSATION INPUT of system 1 with compensation electrode With switch 19 in COMPENSATE position both systems the current flowing through the compensation electrode connected to system 1 is then the sum of both COMPENSATION channels Thus the current of all injection electrodes are balanced with only one compensation electrode
24. witch to set the mode of operation In SET position the electrode outputs Pe are connected to an internally grounded load and no COMPENSATION signal is generated Thus the SET position is used to preset the desired values at the EJECT RETAIN controls on a well defined basis In the OPERATE position the current preset at the EJECT RETAIN controls will flow through the electrode 13 HEADSTAGE connector 8 pole connector for the HEADSTAGE MVCS C systems or for the cable directly connected to the injecting electrode MVCS systems Important Always turn power off when connecting or disconnecting headstages from the 19 cabinet see also chapter 1 14 NORMAL INVERTED switch es Switch to set polarity of EJECT and RETAIN current NORMAL EJECT positive S RETAIN negative 15 TTL connector a Optically isolated BNC connector for external control in the AUTO mode see also 16 LO RETAIN HI EJECT 16 EJECT RETAIN AUTO switch zy Switch to select the mode of operation EJECT the EJECT current set with 7 is uv P applied to the electrode RETAIN the RETAIN current set with 17 is applied to the electrode AUTO Operation controlled by a TTL pulse at 15 Remember Current is applied to the electrode only if switch 12 is set to OPERATE 17 RETAIN potentiometer T Ten turn control to set the RETAIN current range 0 100 nA 18 GROUND connector re Banana jack providing system ground same as GND at
25. ystem MVCS C systems are equipped with an automatic electrode resistance test facility By switching the Vg Igi Rer switch to Rg the value of the electrode resistance is shown on the digital display in MQ The electrode resistance test uses current pulses of 10 nA to measure the electrode resistance These pulses are monitored at the CURRENT OUTPUT BNC and the voltage response can be seen on the Vg 10 BNC In this way changes of electrode resistance can be recorded with a chart recorder or computer based data acquisition system In addition the electrode resistance test mode can be used to tune the fast capacity compensation see chapter 7 1 Electrode resistance test for EJECT channels L In SET mode the resistance inside the headstage 10 MQ is monitored L In OPERATE mode the resistance of the electrode is displayed No square shaped signals should be applied to INPUT connector of the respective channel For testing rectification the EJECT potentiometer or a ramp signal at the INPUT connector should be used instead Testing of rectification of the electrode is done e g by application of different current levels both positive and negative to the electrode using the EJECT potentiometer and testing the resistance of the electrode This resistance must not change over the range of current which is used during the experiment Electrode resistance test for COMPENSATE channel L1 In COMPENSATE or EXTERN mode the resistance of th

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