The name is absent

135

miniscule neural voltages that the system is trying to record. This is especially true with
any system to be used with Cerebus system; the very fine resolution of the NSA restricts
it to a window of +8mV. Any voltage larger than ±8mV will drive the amp into
saturation. To test how quickly the system could recover from a stimulus cycle, a
second function generator was added to the experimental setup which was connected
to two electrodes submerged on opposite sides of the saline beaker which contained
the microelectrode array. The Status output of the mainboard (labeled STAT on the
main board, it gives a high TTL signal when the Stim Project is set to stimulate and a low
signal when set to record) was used to trigger the function generators, this way the first
function generator activated and provided a stimulus signal to the stimulus inputs of the
Stim Project when it was set to stimulate, and when the Stim Project was switched to
record the first function generator turned off and the second function generator
activated, providing a waveform to the saline. By using two distinct waveforms for
stimulation and for the saline, this made it very easy to distinguish the source of all
signals recorded by the Cerebus. A serial port controller program was then used to cycle
the Stim Project through several periods of two seconds of stimulating, followed by four
seconds of recording. Recordings were from the 32 channels connected through the
Stim Project as well as the neighboring 32 channels connected through a headstage
bypass adaptor to make differentiating between capacitance of the microelectrode
array and capacitance and voltage fluctuation of the Stim Project possible.

Figure 2 shows the result of this using a IkHz, 2.5V_pk sinusoid as the stimulating
waveform, and a IkHz, IOmV_pk square wave with a 25% duty cycle as the waveform

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