PSTH and Raster Plot

A peri-stimulus time histogram (PSTH) is the count of a unit's spikes in fixed time bins aligned to a stimulus or behavioral event and averaged across trials; a raster plot is the same spike times drawn as ticks, one row per trial, without averaging. Together they are the standard figure for an evoked response: the raster shows whether the timing is precise, variable or drifting from trial to trial, and the PSTH gives the onset latency, duration and magnitude of the average response. Bins of 1 to 50 ms are typical.

Both are computed from a unit's spike train and event times on the same clock, which is a recording-chain requirement rather than an analysis one: the event stream and the neural stream must be timestamped by the same data acquisition system, through its GPIO ↗ inputs, or the alignment is only as good as the two clocks. In Radiens a PSTH accumulates live as trials stream in Allego and is available post hoc in Videre; a PSTH operates within a trial.