[Classification of cortical neurons according to the character of their background impulse activity]

The method of basic components and cluster analysis was used to classify 75 units in the visual cortex of alert rabbits, proceeding from the empiric form of distribution of interspike intervals (DII), the mean frequency of impulsation and the relative number of intervals up to 500 msec. They were classified into nine groups containing from two to twelve units. Besides the cues, used as a basis for classification, the groups of units also differed in the structure of burst activity, the correlation of adjacent intervals and the ratio between the short (up to 20 to 60 msec) and long intervals. The latter served to make suggestions on the genetic affinity of bimodal DII to those with a bend on the waning after the maximum, and on the nature of formation of high frequency bursts and intervals exceeding 20 to 60 msec.