Dual Mode Extra/Intracellular Headstage

The 8024-7001 Dual Intracellular & Extracellular Headstage extends the use of intracellular amplifiers (IX1 Single Channel Intracellular Preamplifier or IX2-700 Dual Intracellular Preamplifier) to include extracellular recordings. The headstage is a high gain AC coupled amplifier with selectable high pass of 0.3, 3 and 30 Hz. Low pass filtering is done by filters internal to the Intracellular Systems. The Headstage includes all the extracellular features with an additional mode allowing it to function as a normal intracellular headstage. This allows one to record both intracellular and extracellular potentials with the same electrode, without the need to change headstages.

An ultra low noise experimental setup and the absence of capacitive loading effects are possible by the probe headstage containing the first preamplifier gain block and also all circuitry needed for the other microelectrode terminations. An intermediate amplifier stage is located in a small box in line with the cable near the host amplifier and contains the gain selector and filter switch. Gains of 100 or 1000 can be selected, and when combined with gains of 10 or 100 in the mainframe, total gains of up to 100,000 are possible.

Capacitive neutralization is achieved with a high resolution control located on the probe. This feature allows fine tuning of the signal rise times when microelectrode resistances are greater than a few Megohms. A removable three inch long rod allows the probe to be mounted directly to a micromanipulator.

Specifications:
Extracellular mode
Neutralization:         Range 0 to 100 pF, five-turn control on probe
Input Impedance:    >10,000 megohms
Gain:                      x100 or x1000 ± 1%
Low Cut Filter:         0.3, 3, 30 Hz
Overload Recovery: Recovery is very fast, usually one-half to a few milliseconds

Intracellular mode
Input Bias Current:   1 pA (Adjustable to zero)
Rise Time to Pulse:   Typically 10 µs into 10 megohm resistor (10 to 90%),
                               50 µs into 100 megohm
Voltage Gain:            x10
Output Impedance:    500 ohm (all outputs)
Offset Voltage:          200 mV
Balance Reading:       0 to 100 megohm divided by headstage scaling N (ten-turn digital dial)

Electrode Impedance
Test:                        1 mV per megohm square wave (N) Digital Polarization
Current:                   0 to +100 nA (ten-turn digital dial)
Current Multiplier:     (N) = 0.1 for 20 to 500 megohm electrode

Note: Equipment supplied by Dagan Corporation is NOT suitable for connection to human subjects.