KINDLING OF HIPPOCAMPAL FIELD CA1 IMPAIRS SPATIAL-LEARNING AND RETENTION IN THE MORRIS WATER MAZE

We used two procedures to assess the spatial learning and memory of ra ts in the Morris water maze task subsequent to kindling of hippocampal field CA1: (1) seizures were kindled with stimulation of CA1 prior to training in the water maze (acquisition); and (2) maze training was i mposed until performance stabilized, seizures were kindled with stimul ation of CA1, and then performance in the maze was reassessed (retenti on). In both conditions, behavioral testing occurred 24 h after the la st kindled seizure. When the effects of CA1 kindling on acquisition we re tested, we found that kindling of generalized seizures with stimula tion of field CA1 (kindling), but not kindling of non-convulsive or pa rtial seizures (partial kindling), produced deficits in the water maze . When the effects of CA1 kindling on retention were tested, however, we found that kindling of either partial or generalized seizures produ ced deficits in the water maze. The results suggest that the processin g of spatial information is vulnerable to the long-lasting changes in neural excitability associated with kindling.