EEG and behavioral changes in application of Al(OH)3 cream on preoccipital cortex of monkeys.

RECENT experimental studies have demonstrated that extensive ablation of the preoccipital cortex in monkeys (Broadmann's Areas 18 and 19) does not affect their visual status (Lashley,1Chow,* Riopelle and associates4). Animals with such a lesion have normal visual abilities, such as acuity, depth perception, visual field, object recognition, etc., and show good retention of learned visual discriminations. In clinical literature this cortical sector has been considered as a visual integrative center, the damage of which causes severe visual symptoms, notably the various types of visual agnosia (Nielsen5). Beside the possibility of a species difference, the discrepancy between animal experimentation and clinical cases may be due to a difference in the nature of brain injury. It has been suggested that pathological brain tissue may create more irritation and disruption of neural functions than the clean removal of that tissue alone (Hebb6). In animal work, the ablated prestriate