OPERATING INSTRUCTIONS AND
SYSTEM DESCRIPTION FOR THE
EXT-10C
EXTRACELLULAR AMPLIFIER
MODULE FOR EPMS SYSTEMS
VERSION 1.5
npi 2005
npi electronic GmbH, Hauptstrasse 96, D-71732 Tamm, Germany
Phone +49 (0)7141-601534; Fax: +49 (0)7141-601266
support@npielectronic.com; http://www.npielectronic.com
EXT-10C User Manual
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Table of Contents
1. Safety Regulations............................................................................................................ 3
2. EPMS-07 Modular Plug-In System.................................................................................. 4
2.1. Components of the EPMS-07 Housing .......................................................................4
2.2. General System Description / Operation.....................................................................4
2.3. System Grounding....................................................................................................... 5
2.4. Technical Data.............................................................................................................5
3. EXT-10C .......................................................................................................................... 6
3.1. EXT-10C Components................................................................................................ 6
3.2. System Description...................................................................................................... 6
3.3. Signal Flow Diagram................................................................................................... 6
3.4. Description of the Front Panel..................................................................................... 7
3.5. Headstage .................................................................................................................... 9
Headstage Elements..................................................................................................... 9
3.6. Operation..................................................................................................................... 9
4. Literature .......................................................................................................................... 11
5. Technical Data.................................................................................................................. 12
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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) GENERAL: This system is designed for use in scientific laboratories and must be
operated only by trained staff. General safety regulations for operating electrical devices
should be followed.
2) 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.
3) 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.
4) TEMPERATURE DRIFT / WARM-UP TIME: All analog electronic systems are
sensitive to temperature changes. Therefore, all electronic instruments containing analog
circuits should be used 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.
5) HANDLING: Please protect the device from moisture, heat, radiation and corrosive
chemicals.
EXT-10C User Manual
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2. EPMS-07 Modular Plug-In System
2.1. Components of the EPMS-07 Housing
The following items are shipped with the EPMS-07 housing:
EPMS-07 cabinet
Power cord
Fuse 0.8 / 0.4A, slow
Front covers
2.2. General System Description / Operation
The npi – EPMS-07 is a modular system for processing of bioelectrical signals in
electrophysiology (see Figure 1). The system is housed in a 19” rackmount cabinet (3U)
containing a power supply and has room for up to 7 plug-in units. The plug-in units are
connected to power by a bus at the rear panel.
The plug-in units must be kept in position by four screws (M 2,5 x 10). The screws are
important not only for mechanical stability but also for proper electrical connection to the
system housing. Free area must be protected with covers.
In order to avoid induction of electromagnetic noise the power supply unit, the power-switch
and the fuse are located at the rear of the housing.
Figure 1: Example of a measurement system located in an EPMS housing with two channel
iontophoresis and balance module (MVCS-02, MVCC-02), bridge amplifier
module (BRAMP-01R) and an extracellular amplifier module (EXT-01C)
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2.3. System Grounding
The 19" cabinet is grounded by the power cable through the ground pin of the mains
connector (= protective earth, see chapter 1). In order to avoid ground loops the internal
ground is isolated from the protective earth. The internal ground is used on the BNC
connectors or GROUND plugs of the modules that are inserted into the EPMS-07 housing.
The internal ground and mains ground (= protective earth) can be connected by a wire using
the ground plugs on the rear panel of the instrument. It is not possible to predict whether
measurements will be less or more noisy with the internal ground and mains ground
connected. We recommend that you try both arrangements to determine the best
configuration.
2.4. Technical Data
- 19” rackmount cabinet, 3U high (1U=1 3/4” = 44.45 mm), for up to 7 plug-in units
- Power supply: 115/230 Volts AC, 60/50 Hz, fuse 0.8/0.4 A slow, 45-60 W
EXT-10C User Manual
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3. EXT-10C
3.1. EXT-10C Components
The following items are shipped with the EXT-10C system:
Amplifier module for the EPMS-07 system
GND- (2.6 mm banana plug) and REF. (SMB) connectors for headstage
Headstage
User manual
3.2. System Description
The EXT-10C was designed for performing low noise recordings of small extracellular
signals in slices or in in vivo preparations using fine tipped glass or metal microelectrodes.
The system consists of a module for the npi EPMS-07 modular system and a small headstage
with a holding bar.
The EXT-10C has a differential input with high input resistance for minimizing noise and the
incoming signal can be compensated for offset and capacity of the microelectrode by the two
potentiometers OFFSET and C-COMP. An analog balance monitor makes the control of
offsets easy. The recorded signal can be obtained either AC with GAIN of 100, 1k or 10k or
DC with GAIN of 10, 100 or 1k. An optional NOTCH filter eliminates 50/60 Hz noise.
The EXT-10C is designed to be used with the DPA-2F preamplifier/filter module from npi
which combines additional gain stages with high- and lowpass filters.
3.3. Signal Flow Diagram
The signal is passed through the EXT-10C as shown below.
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3.4. Description of the Front Panel
Figure 2: EXT-10C front panel view
In the following description of the front panel elements each element has a number that is
related to that in Figure 2. 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.
(1) HEADSTAGE connector
The HEADSTAGE cable is connected to the unit at an 8-pin connector in the center
of the module.
(2) DC OUTPUT connector
BNC connector providing the amplified signal DC coupled. The amplification factor
is set by the GAIN DC switch (3).
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(3) GAIN DC switch
Switch to set the GAIN of the outgoing DC signal. Three GAIN factors are
available: x10, x100 or x1k.
(4) C-COMP. potentiometer
Control for compensation of stray capacities of the microelectrode (10 turn
potentiometer, range 0-20 pF). Due to the positive feedback circuit
overcompensation of the capacity will lead to oscillations which may damage the
cell.
(5) POTENTIAL x10 meter
The analog POTENTIAL monitor displays the offset in the range of ±30 mV
and is used for optimal cancellation of the OFFSET.
(6) –OVER +OVER LEDs
LEDs that indicate if the amplifier 10% below it’s positive or negative limit
(±10 V). The linear range of the amplifier is ±12 V.
(7) OFFSET potentiometer
10 turn potentiometer to compensate for the OFFSET of a DC signal.
Note: Position 5 on the OFFSET control corresponds to 0 mV offset.
(8) GAIN AC switch
Switch to set the GAIN of the outgoing AC signal. Three GAIN factors are
available: x100, x1k or x10k.
(9) AC OUTPUT connector
BNC connector providing the amplified signal AC coupled. The amplification factor
is set by switch (8).
(10) NOTCH switch (optional)
Switch to set the NOTCH filter (50 Hz / 60 Hz) or to bypass the NOTCH filter (switch
position OFF).
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3.5. Headstage
Figure 3: electrode holder (optional) and headstage of the EXT-10C
Headstage Elements
1 BNC connector for the electrode holder
2 REF: reference electrode connector
3 GND: ground connector
4 holding bar
On request, P
EL
can be implemented using 1 mm or 2 mm banana jacks or using SMC
SUBCLIC connectors.
3.6. Operation
Extracellular measurements are mostly done in slices or in vivo, where distortions of the
signal caused by other instruments and the animal itself are very common. Additionally,
extracellular signals are very small and have to be amplified enormously. The drawback is
that noise is amplified as well. Therefore, the headstage of the EXT-10C is equipped with a
differential input that minimizes noise pick-up. Differential means, that the signal for the
amplifier is the difference between the positive (+) (P
EL
) and negative (-) (REF.) input of the
headstage. This results in canceling of all signals which both electrodes record, e.g. noise.
For differential measurements, both inputs of the headstage (REF. and P
EL
) are connected to
microelectrodes using cables with grounded enclosure or electrode holders. P
EL
is connected
to the measuring electrode and REF. to the reference electrode. The experimental chamber is
grounded by an Ag-AgCl pellet (or an AGAR bridge) connected to GND of the headstage
(see Figure 4).
If differential measurement is not required (single-ended measurement configuration, see
Figure 4), the REF input must be connected to ground (GND). The amplifier is in an
undefined state, if the REF is left open, and can go into saturation making reliable
measurements impossible.
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Figure 4: headstage connections, A: differential measurement, B: single-ended measurement
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4. Literature
Barmashenko, G., Eysel, U. T., & Mittmann, T. (2003). Changes in intracellular calcium
transients and LTP in the surround of visual cortex lesions in rats. Brain Res. 990, 120-
128.
Boulton, A. A., Baker, G. B. & Vanderwolf, C. H. (eds.) (1990). Neurophysiological
Techniques, Basic Methods and Concepts. Humana Press, Clifton, New Jersey.
Huemmeke, M., Eysel, U. T., & Mittmann, T. (2002). Metabotropic glutamate receptors
mediate expression of LTP in slices of rat visual cortex. Eur.J.Neurosci. 15, 1641-1645.
Huemmeke, M., Eysel, U. T., & Mittmann, T. (2004). Lesion-induced enhancement of
LTP in rat visual cortex is mediated by NMDA receptors containing the NR2B subunit. J
Physiol 559 , 875-882.
Schulz, D., Huston, J. P., Jezek, K., Haas, H. L., Roth-Harer, A., Selbach, O., & Luhmann,
H. J. (2002). Water maze performance, exploratory activity, inhibitory avoidance and
hippocampal plasticity in aged superior and inferior learners. Eur.J.Neurosci. 16, 2175-
2185.
Kettenmann, H. & Grantyn, R. (eds.) (1992). Practical Electrophysiological Methods.
Wiley-Liss, New York
Lalley, P.M., A.K. Moschovakis and U. Windhorst (1999) Electrical Activity of Individual
Neurons In Situ: Extra- and Intracellular Recording, in: U. Windhorst and H. Johansson
(eds.) Modern Techniques in Neuroscience Research, Springer, Berlin, New York
Müller, Ch.M. (1992) Extra- and Intracellular Recording in the Slice, in: Kettenmann, H.
& Grantyn, R. (eds.) Practical Electro-physiological Methods, Wiley-Liss, New York
Ogden, D. (ed.) (1992) Microelectrode Techniques - The Plymouth Workshop Handbook,
Second Edition, The Company of Biologists Ltd., Cambridge
Seidenbecher, T. and H.C. Pape (2001) Contribution of intralaminar thalamic nuclei to
spike-and-wave-discharges during spontaneous seizures in a genetic rat model of absence
epilepsy, European Journal of Neuroscience, Vol. 13:1537-1546
Windhorst, U. and H. Johansson (eds.) (1999) Modern Techniques in Neuroscience
Research, Springer, Berlin, Heidelberg, New York
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5. Technical Data
Differential Input: CMR >90 dB at 1 kHz (tested with 0 Ω input resistance)
Input resistance: >10
12
Ω, range ±1 V
Output DC: selectable gain (x10, x100, x1k)
Output range: ±12 V into 1 kΩ / ±1 V into 50 Ω load
Output AC: selectable gain (x100, x1k, x10k)
Output range: ±12 V into 1 kΩ / ±1 V into 50 Ω load
corner frequency 10 Hz
Offset compensation: 10 turn potentiometer, ±100 mV
Potential monitor: analog display for the electrode offset, range: ±30 mV
Capacity compensation: 0-20 pF, 10 turn potentiometer
Size: front panel 12 HP (60.6 mm) x 3U (128,5 mm), 7” (175 mm) deep
EPMS-07 SYSTEM
Power Requirements: 115/230 V AC, 60/50 Hz, fuse 0.8/0.4 A, slow, 45-60 W
(dependent on the modules plugged in)
Dimensions: 19” rackmount cabinet, 3U high (1U = 1 3/4” = 44.45 mm)
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