PSYCHOLOGICAL STRESS IMPAIRS SPATIAL WORKING-MEMORY - RELEVANCE TO ELECTROPHYSIOLOGICAL STUDIES OF HIPPOCAMPAL FUNCTION

Stress blocks hippocampal primed-burst potentiation, a low threshold f orm of long-term potentiation, thereby suggesting that stress should a lso impair hippocampal-dependent memory. Therefore, the effects of str ess on working (hippocampal-dependent) and reference (hippocampal-inde pendent) memory were evaluated. Rats foraged for food in seven arms of a 14-arm radial maze. After they ate the food in four of the seven ba ited arms, they were placed in an unfamiliar environment (stress) for a 4-hr delay. At the end of the delay they were returned to the maze t o locate the food in the 3 remaining baited arms. Stress impaired only working memory. Stress interfered with the retrieval of previously st ored information (retrograde amnesia), but did not produce anterograde amnesia. Stress appears to induce a transient disruption of hippocamp al function, which is revealed behaviorally as retrograde amnesia and physiologically as a blockade of synaptic plasticity.