STABILITY OF SPATIAL WORKING-MEMORY ACROSS THE ESTROUS-CYCLE OF LONG-EVANS RATS

In the adult rat, hippocampal dendritic synaptic connectivity in regio n CA1 fluctuates across the estrous cycle. This study examined the pot ential functional impact of such fluctuations on spatial working memor y in regularly cycling Long-Evans rats. Rats were trained in a delayed non-match-to-sample radial-arm maze task and performance was monitore d across the estrous cycle. There were no significant alterations in t he acquisition or performance of the working memory task across the es trous cycle, with 1- or 4-h delays imposed between training and testin g sessions. However, rats performed the task significantly more slowly on proestrus than on any other estrous cycle day under both delay con ditions. These results indicate that while working memory remains stab le, sensorimotor or motivational aspects of the performance of this ra dial-arm maze task may vary across the estrous cycle. (C) 1997 Academi c Press.