Z score normalization

For each neuron, and for each trial type, firing rate (Hz) was calculated in 250 ms bins from 20 s prior to cue onset to 20 s following cue offset, for a total of 200 bins. Mean firing rate over the 200 bins was calculated by averaging all trials for each trial type. Mean differential firing was calculated for each of the 200 bins by subtracting mean baseline firing rate (2 s prior to cue onset), specific to that trial type, from each bin. Mean differential firing was Z score normalized across all trial types within a single neuron, such that mean firing = 0, and standard deviation in firing = 1. Z score normalization was applied to firing across the entirety of the recording epoch, as opposed to only the baseline period, in case neurons showed little/no baseline activity. As a result, periods of phasic, excitatory and inhibitory firing contributed to normalized mean firing rate (0). For this reason, Z score normalized baseline activity can differ from zero. Z score normalized firing was analyzed with ANOVA using group, bin and trial type as factors. F and p values are reported, as well as partial eta squared (η_p²) and observed power (op).