MONOCULAR ENUCLEATION PREVENTS RETINAL GANGLION-CELL LOSS FOLLOWING NEONATAL VISUAL-CORTEX DAMAGE IN CATS

Damage to primary visual cortex (VC) in young cats leads to severe ret rograde degeneration of the dorsal lateral geniculate nucleus (dLGN) a nd selective transneuronal retrograde degeneration of a class of retin al ganglion cells (RGCs) that have a medium-size soma. Previous studie s have shown that ''programmed'' RCC death associated with normal deve lopment in one eye can be attenuated by removal of the other eye, sugg esting that binocular interactions can influence developmental RGC dea th. The present study investigated whether removal of one eye also att enuates the ganglion cell loss that accompanies an early VC lesion. Fi ve one-week-old cats received a unilateral VC lesion (areas 17, 18, an d 19), and three of these cats also underwent monocular enucleation at the same time. Two normal control animals also were examined. RGC mea surements were made from flat-mounted retinae when the animals were 5 weeks old. Sampling was restricted to a retinal area corresponding to the retinotopic representation included in the VC lesion. Results indi cate that there is a marked loss of medium-size RGCs in the hemiretina e projecting to the damaged hemisphere in cats that received a VC lesi on alone. However, there is no such loss in VC-lesion animals that als o have a monocular enucleation. These results indicate that the transn euronal RGC loss that occurs after an early visual cortex lesion can b e influenced by binocular interactions.