Cortical Information Processing as Viewed from the Mass-Action Domain of Evoked Potentials

Abstract

The two most fundamental fields concerned with the cortical processing of visual information, anatomy and single-cell physiology, have yielded rather divergent results. Anatomical investigations, on the one hand, have revealed a rather chaotic, dense net of local and widespread interconnections between the cortical neurons. This net of interconnections lacks any apparent spatial order with respect to lengths or densities in the vertical and horizontal directions (Schüz, Braitenberg, this volume). The physiological studies of single cells’ response properties, on the other hand, have demonstrated that external information is represented in the visual cortex in a highly specific manner and arranged in a very precise spatial order. The individual cells’ receptive fields (RFs) are small; the retinotopic relation is preserved for these RFs between hypercolumns. Moreover, each hypercolumn is further spatially subdifferentiated into ocular dominance- and orientation columns and in the monkey, additionally into color-, motion-, and form-processing subregions (Barlow, this volume). Thus, in contradiction to the results of the intracortical network, RF studies indicate that afferent information is processed in the cortex in a parallel fashion, and in a rather independent manner within each subregion or microcolumn, without strong lateral interactions.