Simple and B-cells in cat striate cortex. Complementarity of responses to moving light and dark bars

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Abstract
This report is based on the quantitatively recorded responses of 72 striate cells in the simple (S and SH) and B-cell (B and BH) families to narrow (0.14 degrees) moving light and dark bars. Cells were regarded as hypercomplex (SH and BH) if the end-zone inhibition reduced the response to 50% of its peak value. The contrast of the bars was relatively low and matched to be equal but opposite for the two kinds of bar. Average response histograms to the two kinds of bar were recorded separately and only subsequently combined. The response histogram from a given S- or SH-cell shows separate response peaks to the light and dark bars. The number of peaks varies from two to five in different cells. Cells with two response peaks were encountered most commonly (54%), and rather less common were cells with three (31%), four (7.5%), and five (7.5%) peaks. By defining the sequence of the response peaks according to the direction preferred by a moving light bar, the number of distinct spatial patterns of responses to the moving bars increases from four to eight since the first response in the sequence can be either to a light bar or to a dark bar. Examples of all eight responses have been recorded. For cells in the simple family with two response peaks, as well as for B-cells, the width of the light-bar peak was the same as, or closely similar to, that of the dark-bar peak. For S- and SH-cells with more than two response peaks this was also true for the two principal peaks, namely the largest and the next-largest immediately adjacent peak. In the simple family, the mean widths of the two principal response peaks remained closely similar despite the progressive decrease in their respective widths as the number of peaks in the pattern increased from two to five. The mean width of the two principal response peaks from S- and SH-cells (0.6 degrees) was significantly less than the mean width for B-cells (1.4 degrees). For simple-family cells the spatial overlap between the two principal peaks (mean 14%) was always less than 50% of the overall width of the two peaks, whereas for B-cells the overlap (mean 79%) was always greater than 50%. For cells in both the simple and B-cell families the length of the receptive field as given by a moving light bar is the same as that given by a moving dark bar.(ABSTRACT TRUNCATED AT 400 WORDS)