Effects of unilateral cerebral ischemia on the hippocampal theta depth profile in the ether-anesthetized Mongolian gerbil.

In gerbils (Meriones unguiculatus) unilateral cerebral ischemia of 5 to 15 min resulted in selective destruction of the ipsilateral hippocampal CA1 stratum pyramidale. It also produced an obvious amplitude reduction in both superficial and deep theta rhythms recorded from damaged hippocampal formation. The presence of normal theta in the left normoxic hemisphere showed that the septohippocampal projections, integrity of which is essential for theta appearance, were spared by ischemia. These data have implications in relation to the two generators hypothesis of theta.