CONTRASTING EFFECTS OF SYSTEMIC AND INTRACEREBRAL INFUSIONS OF THE 5-HT1A RECEPTOR AGONIST 8-OH-DPAT ON SPATIAL SHORT-TERM WORKING-MEMORY IN RATS

The present study compared the effects of systemic 8-OH-DPAT (0.05, 0. 1 and 1.0 mg/kg) with intra-raphe and intra-hippocampal infusions of 8 -hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (10, 30 100 ng) on d elayed non-matching-to-position (DNMP) performance in rats. The highes t dose of 8-OH-DPAT administered systemically impaired DNMP performanc e in a delay-independent manner, increased premature responding and in creased response bias. Infusions of 8-OH-DPAT (100 ng) into the median raphe nucleus improved performance accuracy, independent of delay whi lst having no effect on any other response measure. Infusions of 8-OH- DPAT into the dorsal raphe nucleus had no effect on performance at any dose tested. Infusions of 8-OH-DPAT into the dorsal hippocampus produ ced a small impairment in performance which was also independent of de lay. However, this decrement in performance accuracy was not accompani ed by any changes in other response measures. These findings demonstra te a dissociation between the effects of stimulation of pre- and post- synaptic 5-HT1A receptors on performance of a DNMP task although the c hanges in performance cannot be accounted for by changes in mnemonic f unction.