Preservation of a functionally intact neuronal network after global ischemia.

Although conventional histological techniques demonstrated preservation by drug treatment of neuronal perikarya in the hippocampal CA1 region in animals subjected to short periods of transient ischemia, uncertainty exists regarding whether the anatomical connections with these neurons are intact and functional. The hippocampal theta rhythm is dependent upon intact connections to the CA1 pyramidal neurons and is a useful predictor of functional hippocampal integrity. Hippocampal theta was quantitated by power spectral analysis in rats subjected to 30 min of 4-vessel occlusion (4-VO) and treatment with the neuroprotective antioxidant, LY231617. The 4-VO destroyed CA1 neurons and reduced the amount of theta, however, LY231617 protected CA1 neurons histologically and totally preserved the hippocampal theta rhythm. We conclude that histological preservation is indicative of functional integrity.