Posttrial hippocampal stimulation and CER acquisition in the rat.

Gave 27 female Holtzman albino rats CER training, with each CS-UCS pairing followed by hippocampal stimulation through chronically implanted electrodes. Findings show that (a) localized posttrial stimulation may have blocked CER acquisition, although individual Ss differed considerably in degree of impairment; (b) the blocking was due neither to an implant-produced lesion nor to reinforcing properties of the stimulation; and (c) stimulation passed through separated electrodes spanning a large area of hippocampus was effective at both high and low current levels, with or without concomitant electrographic afterdischarges. Results indicate that posttrial hippocampal stimulation interferes with CER consolidation, and suggest that there may be critical locations within hippocampus whose activity must be disrupted in order for the blocking to occur. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)