Parallel convergences: a glimpse to the magno-and parvocellular pathways in visual perception.
Convergenze parallele: un'occhiata alla via magno- e parvocellulare nella percezione visiva
Carlo Aleci, Elena Belcastro
World Journal of Research and Review, 3(3), 34-42, 2016.
Abstract
The visual processing of an object is provided by two distinct, parallel retinocortical pathways: the parvocellular ( P-) or sustained system, and the magnocellular (M-) or transient system. The P system is made of small ganglion cells and arranged in receptive fields of small size. In turn, the M system is made of larger ganglion cells, arranged in wider receptive fields. Like their anatomical features, also information carried by the M and P cells is different and basically complementary, at least at the subcortical level. A common opinion in the last decades supports the idea that a model based on this parallel M/P complementary processing of the image may account for the various aspects of visual perception. Yet, tracing separately M and P information beyond the striate cortex turns difficult due to diffuse anatomical crossroads, functional intermixing, and to the overlapping of the psychophysical response. The present paper aims at making the point on this issue, highlighting the reported caveat for an attractive, albeit probably too simplified (therefore potentially misleading) schematization.
Keywords: Magnocellular, Parvocellular, Contrast Sensitivity, Color, Motion, Shape, Ocular Movements
