Functional significance of sympathohippocampal sprouting: changes in single cell spontaneous activity.

The electrophysiological consequences of noradrenergic sympathohippocampal ingrowth following medial septal lesions were investigated. Spontaneous activity of single dentate neurons was recorded in anesthetized rats with and without sympathohippocampal ingrowth. In animals with medial septal lesions (ingrowth) spontaneous firing rates were not different from rates in normal animals. Medial septal lesions combined with bilateral superior cervical ganglionectomy (no ingrowth) resulted in a significant 82% increase in spontaneous activity.