Correlation between the preferred orientation and spatial frequency of neurones in visual areas 17 and 18 of the cat.

Publisher Website
Google Scholar
Abstract
In 76 penetrations through areas 17 and 18 of the cat, neurons were regularly sampled at intervals of 100 .mu.m and preferred orientation, optimal spatial frequency and resolving power were determined for each neuron in response to drifting sinusoidal gratings. As already shown for area 17, in tangential penetrations through area 18, whenever the preferred orientation rotates progressively from cell to cell, the optimal spatial frequency tends to remain constant. A statistical analysis on 1574 cells in areas 17 and 18 showed that for pairs of cells separated 200-300 .mu.m along a track the difference in preferred orientation .DELTA..alpha. and the difference in optimal spatial frequency .DELTA.f are not randomly distributed: cell pairs with small .DELTA..alpha. are most likely to have large .DELTA.f and vice versa. In areas 17 and 18, neurons with the same optimal frequency seem to be aligned along a direction orthogonal to the orientation columns. The optimal spatial frequency, resolving power and the velocity cut-off were averaged for cells from different penetrations located in the same cortical layer or sublayer of area 18: mean optimal spatial frequency and acuity are highest in layer IV and lowest in layers II and V, while the velocity cut-off is highest in layers II and V and lowest in layer IV. Evidently, the layering of cells according to optimal spatial frequency is a more subtle subdivision than the 6 histological layers.