Postischemic hyperactivity in the Mongolian gerbil correlates with loss of hippocampal neurons.

Gerbils show a postischemic increase in locomotor activity that correlates to the extent of neuron loss in the hippocampal CA1 subfield. It has been suggested that this hyperactivity is predictive of neuron loss in the CA1. In this study the correlation between postischemic hyperactivity and neuron loss in several hippocampal subfields was investigated, and the theory that the hyperactivity is due to a reduced ability for spatial navigation was evaluated. Significant correlations were found between hyperactivity and neuron loss in several hippocampal subfields; the correlation was stronger for the CA3 than for the CA1 subfield, suggesting that postischemic hyperactivity can be used as a predictor of neuron loss in the CA3 rather than in the CA1. From observations of the pattern of hyperactivity within the test arenas and during the test period, this study challenges the spatial mapping theory of postischemic hyperactivity.