Regional variations in the effects of monocular deprivation on area 18 of the cat

Summary

We have studied the effects of monocular deprivation (MD) on area 18 in the cat. Our intention was to determine whether the degree of vulnerability to MD varies regionally within area 18. Single units were recorded in animals used as normal controls (77 cells) and in MD cats (467 cells) from anterior and posterior regions of area 18 representing peripheral and central-paracentral fields, respectively. Recordings from the deprived cats were made from both hemispheres. Overall, around 27% of the cells from the MD group retained input from the deprived eye. Most of these cells (77%) were located in the hemisphere contralateral to the deprived eye. Furthermore, the majority of these cells (96%) were located in the anterior region of area 18 and had receptive fields at eccentric locations (greater than 10 deg). About one third of the cells driven by the deprived eye had diffuse receptive field borders, and most of these units were binocular. In addition, these cells were generally non-oriented. Our main result, that susceptibility to MD decreases with increasing receptive field eccentricity, may be accounted for on the basis of corresponding changes of spatial frequency selectivity of cortical cells.