Hypercomplex and simple/complex cell classifications in cat striate cortex.

Abstract

The response properties and receptive-field organization of 112 oriented striate neurons (simple, 43; hypercomplex I, 37; complex, 17; hypercomplex II, 15) in 13 anesthetized (N2O/O2) and paralyzed cats were examined by both hand and quantitative methods with particular reference to the hypercomplex property and its relation to the simple and complex cell classifications. Nearly all the cells had receptive fields within 5.degree. of the center of gaze. End-stopped cells (46%) were almost as commonly encountered as end-free cells (54%). The hypercomplex property appears to be very largely, if not completely, independent of the simple/complex classification. The relative proportion of end-stopped cells was virtually the same in the simple (46%) and in the complex (47%) families. The optimal stimulus length for hypercomplex cells was nearly always shorter than that for simple and complex cells. Hypercomplex cells be reliably discriminated by hand methods. Hypercomplex cells were found in all cell laminae of the striate cortex but were principally encountered in lamina II + III and lamina V. The receptive-field discharge regions of striate cells plotted by quantitative methods differed markedly from those obtained by hand methods. The criteria for distinguishing the simple and complex families were critically reviewed.