Computer analysis of some cat parahippocampal unit firing patterns

Twenty-five cat parahippocampal gyrus unit spike trains were analyzed for firing time characteristics. Autocorrelation interval and 2 new types of histograms displayed data sampled from spontaneously firing units. For 7 units, spikes occurring within a 40 msec period were not generally followed by a spike in the 40-90 msec period following the first spike. Evoked feedback inhibitory influences, being most effective at 40-60 msec following each spike and summing over time, may account for the 40-90 msec zero or small firing probabilities. Spikes occurred between 60-90 msec following a previous spike but were not generally preceded by a firing in the 1-40 msec period.In other trains, spikes occurring within a 30 msec period were followed most frequently by a spike or spikes in the 350-410 msec period following the first firing. When the interval between 2 firings was greater than 30 msec probabilities for future spikes were nearly equal for all times up to 1000 msec. Autocorrelation interval histogram peaks at 350-410 msec intervals were dependent upon the serial arrangement of intervals in the train. Inputs, evoking 2 or more firings within a 30 msec period, may have been periodically impressed on the cells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32782/1/0000155.pd