Multichannel Systems MC_Rack Manual - Manual (Page 139)

MC_Rack Features
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Examples:
The following examples further illustrate the possible combinations of the Feedback Logic.
In example one, single spikes are detected on two channels combined with the condition OR.
Hence, the logical state of each channel is TRUE from the detection of an event till the end of
the event duration (shown in red). As the two channels are combined with OR, a TTL is generated
as long as any of the two channels, or both, have the logical state TRUE.
In example two, the same channels are combined with the condition AND. This means, a TTL is
generated only if both channels have the logical state TRUE. This setting can be used to detect
simultaneous events. By adjusting the event duration, it is possible to define how close together
two events have to be to trigger a feedback stimulation.
Important: In extreme cases, if the overlap between the TRUE states of all selected channels is
very short (below 20 μs), the generated TTL might be too short to trigger the stimulus generator.
In example three, spike rates are detected with the condition eight spikes per time window.
The two channels are combined with the condition OR. The logical state of channel one becomes
TRUE upon detection of the eighth event in the time window until the last event that fulfils the
condition, plus the event duration. In channels two, the event rate is too low. As both channels
are combined with OR, the TRUE state of channel one is sufficient to trigger a TTL output.
In example four, the overall event rate of channel one and two is combined and the condition
is again eight events per time window. The addition of both channels results in longer and more
TTL outputs. As the activity of both channels is counted together anyway, the combination
parameter AND / OR is not applicable.