Effects of regional GABAergic blockade of the striatum on memory consolidation.

The prediction was made that blocking the action of gamma-aminobutyric acid (GABA) in different regions of the striatum, through local injection of picrotoxin, would produce differential amnestic effects. Rats were trained in an inhibitory avoidance task, and a retention test was carried out 24 h later. Posttraining injection of picrotoxin (1 microgram/1 microliter) into posteroventral and lateral regions produced strong amnesia; an intermediate degree of impairment was found when delivered at dorsomedial regions; and no retention deficit was found when given to the ventromedial aspect of the anterior striatum. In sum, the retention impairments were consistently higher in posterior and lateral striatal regions than in the anterior and medial regions. The present findings support the concept that striatal GABAergic activity is involved in memory functions and also provide further evidence of neurochemical heterogeneity within the striatum regarding memory consolidation.