Name: Axon Axopatch 200B
Brand: Axon
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PRINCIPLES OF OPERATION

adjustment is particularly important during series resistance correction (see Series

Resistance section in

PRINCIPLES OF OPERATION

) since it increases the

current-passing demands on R

. By moving the pathway for charging the

membrane capacitance from R

to C2, the SERIES RESISTANCE circuitry can

operate without causing the headstage input to saturate. The value of C2 is 1 pF.

The effect of transferring the current-passing burden from R

to C2 is illustrated in

Figure 20.

-c

Figure 20.

Using the injection capacitor to charge the membrane capacitance.

After perfect whole-cell compensation is applied, the current to charge the

membrane capacitor is removed from the I

trace and only the steady state current

remains. All of the transient current appears in the I

trace. (The I

trace in the

figure was recorded using an oscilloscope probe connected to the internal

circuitry). The I and V

outputs on the Axopatch 200B show the I

and V

trace

illustrated in Figure 20. It is easy to mistakenly think that the time course for

charging the membrane is very fast but this is clearly not the case. Use of an

independent electrode in the cell would show that the cell charging rate is not

affected by these adjustments.

Axon Axopatch 200B User Manual

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