INFUSION OF D-CYCLOSERINE INTO TEMPORAL-HIPPOCAMPAL AREAS AND RESTORATION OF MNEMONIC FUNCTION IN RATS WITH DISRUPTED GLUTAMATERGIC TEMPORAL SYSTEMS

Partial transections of the fiber connections between the temporal cor tex and the lateral entorhinal cortex at a site of the white matter co rresponding to the perirhinal cortex result in impaired visual memory accompanied by reduced concentrations of glutamate in both the tempora l cortex and lateral entorhinal cortex. Intraperitoneal administration of the glycinergic receptor agonist D-cycloserine produces complete r estoration of memory function, as measured by a brightness discriminat ion task in rats with temporal cortex/lateral entorhinal cortex transe ctions. The purpose of the present study was to identify in which brai n structures the compensatory activity might take place. The results s how that infusion of cycloserine into either the temporal cortex or la teral entorhinal cortex fully ameliorated the impairment of temporal c ortex/lateral entorhinal cortex lesions, whereas infusion into the hip pocampal region caused only a mild improvement of the retention perfor mance. Infusion of cycloserine into the frontal cortex or saline into the temporal cortex or lateral entorhinal cortex had no ameliorating e ffects on the memory dysfunction of rats bearing temporal cortex/later al entorhinal cortex transections. It is concluded that the temporal c ortex, lateral entorhinal cortex and perirhinal cortex are highly crit ical in forming visual memory.