K. Albus

A quantitative study of the projection area of the central and the paracentral visual field in area 17 of the cat

Summary1.In the course of long oblique penetrations through the postlateral gyrus a variation in the position of the receptive fields (RF-scatter) of single cells recorded extracellularly is observed. This is superimposed on the continuous topological representation of the retina. Spezifying the RF-positions by the azimuthal and elevation coordinates of their geometrical centers, the standard deviation (SD) of the mean RF-positions of cells recorded in 200 μm long horizontal sections of cortex is calculated and the total radial scatter of RF-positions (Sanderson, 1971) as defined:

14C-Deoxyglucose mapping of orientation subunits in the cats visual cortical areas

\sqrt {\left( {{\text{4SD azimuth}}} \right)^2 + \left( {4SD{\text{ elevation}}} \right)^2 }

The depth distribution of optimal stimulus orientations for neurones in cat area 17

is determined. The radial scatter is found to have its smallest value (1 degree visual angle (v.a.)) in the projection area of the functional center of the area centralis increasing to 3–4 degrees v.a. at 10 degrees eccentricity.2.The mean RF-diameter as defined:

On the spatial arrangement of iso-orientation bands in the cat's visual cortical areas 17 and 18: a 14C-Deoxyglucose study

\sqrt {{\text{mean RF - area}}}

The geniculocortical system in the early postnatal kitten: An electrophysiological investigation

is centrally 0.7 degrees v.a. increasing to 2.6 degrees v.a. at 10 degrees eccentricity. The ratio of the largest RF-diameter to the smallest RF-diameter is between 7–9 and remains almost constant over the central 10 degrees of the projection area. The magnification factor (M) as defined: mm Cortex/degree v.a. is centrally 2.3, decreasing paracentrally to 0.6.3.The cells in area 17 whose RFs have the same direction in the visual field constitute the spatial subunit of the retinocortical projection. The diameter of the spatial subunit is calculated as: