DISSOCIATION BETWEEN COGNITIVE AND MOTOR MOTIVATIONAL DEFICITS IN THEDELAYED MATCHING TO POSITION TEST - EFFECTS OF SCOPOLAMINE, 8-OH-DPATAND EAA ANTAGONISTS/

The effects of the muscarinic antagonists scopolamine HBr and MeBr, th e 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a nd the N-methyl-d-aspartate (NMDA) antagonists MK-801 and CGS-19755 on performance of rats in a delayed matching-to-position task were exami ned. Pretreatment with scopolamine HBr (0.05 and 0.1 mg/kg), resulted in a delay-dependent decrease in the percentage of correct responses a nd discriminability (log d), but had no effect on either the latency t o complete trials, or the rate of trial completion during the fixed du ration session. Scopolamine MeBr (0.1 mg/kg) did not impair percent co rrect or increase the response latency but did decrease the rate of tr ial completion. 8-OH-DPAT (up to 0.3 mg/kg), had no effect on percent correct, but did induce a small decrease in discriminability. The impa irment in discriminability occurred only at a dose that substantially reduced the rate of trial completion. Both MK-801 (0.05 mg/kg) and CGS 19755 (10 mg/kg) induced a delay-independent impairment in percent co rrect, discriminability and a reduction in the rate of trial completio n without affecting latency. A lower dose of CGS 19755 (5.0 mg/kg) ind uced a slight impairment in discriminability without significantly aff ecting the other measures. Taken together, these results demonstrate s ome dissociation between drug-induced cognitive and motor/motivational deficits in the DMTP test. However, the data question the specificity of putative cognitive impairments reported in many previous studies w ith the 5-HT1A agonist 8-OH-DPAT.