Simultaneous evaluation of spatial working memory and motivation by the allocentric place discrimination task in the water maze in rats

In order to evaluate learning and memory deficits separately from and simul taneously with motivational, motor and sensory impairments in identical ani mals, we developed the allocentric place discrimination task test using a w ater maze in rats. For this assessment task, two similar, visible platforms , one was fixed and the other was floating, were simultaneously present in a pool, and the working memory of the allocentric place discrimination task was evaluated. After training, the task accuracy was high about 85% correc t and animals were used repeatedly. The accuracy decreased significantly wh en the pool was surrounded with a black curtain. Muscarinic receptor antago nist scopolamine 0.5 mg/kg selectively impaired the accuracy. Muscle relaxa nt dantrolene 10 mg/kg selectively decreased swimming speed. Under low moti vational condition (warm water), still time increased and swimming speed de creased, but the accuracy was not affected. Similar to warm water, opioid r eceptor agonist morphine 15 mg/kg increased still time and decreased swimmi ng speed. These results suggest that the allocentric place discrimination t ask is useful in evaluating spatial working memory ability independently of and concurrently with also visual, motor ability and motivation in identic al animals.