Cells of origin of the occipito-pontine projection in the cat: functional properties and intracortical location.

Extracellular records were taken from the areas 17, 18 and 19 of anaesthetized and immobilized cats. Of the 350 cells recorded in the cortical layers IV-VI, 22 responded with an antidromic action potential to electrical stimulation of the basal pontine region. Antidromic latencies ranged between 1.5-8.8 msec (mean and SD: 3.98 +/- 1.83 msec). The recording sites of these cells were in the cortical layer V. In the areas 17 and 18 of these cells were detected only in peripheral parts of the visual field representation. Some of these cells were tested with visual stimulation. They had complex receptive fields of large sizes, they received input from either eye, and their orientation selectively was relatively low. The sample of cells had neither a preference for a certain orientation nor for any particular degree of directional specifity nor for a certain range of movement velocity.