2022-08-28 • Centred STAs
2022-08-28 • Centred STAs¶
Center spike-triggered windows around 0 (mV) before averaging them.
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This is useless (in terms of increasing ‘SNR’ of the STA):
If the current STA is this [1]:
(where \(s\) is the presynaptic spiketime, \(N\) the number of such spikes, \(W\) the window length, and \(V\) the voltage / VI signal),
then the new STA would be:
In other words:
i.e. the STA waveforms would be the same as the current ones, just shifted vertically by some value (namely the average voltage at the start of the window; or, if we had rather chosen \(\texttt{mean}(V[s:s+W])\) as referencing value instead of \(V[s]\): the average voltage of all windows).
[1] Note that this notation is more programm-y than mathy, with the \([…:…]\) slicing notation. In usual math notation we’d express it per timepoint: \(STA[t] = \frac{1}{N} \sum_s V[s+t]\), with \(t = 0, 1, …, W\).
This idea would thus have no effect on connection detectability using the peak-to-peak measure (it would stay the same).
Neither would it have an effect on the ‘exc or inh’ test, as that one already uses the \(STA[1]\) as reference value.