Correlational relationships between the hippocampus and medial septal area and their changes during epileptogenesis

EEG traces were recorded from the hippocampus and medial septal area of conscious guinea pigs in control conditions and on repeated stimulation of the perforant path. Changes in the correlations of activity in these structures during stimulation-evoked convulsions (a model of acute epilepsy) and during the process of epileptogenesis (a model of chronic epilepsy) were analyzed. A high correlation between baseline activity in the hippocampus and medial septal area seen in control conditions decreased sharply with the appearance of acute and chronic convulsions. Kindling led to hippocampus-independent generation of field convulsive discharges in the medial septal area. During kindling, there was a gradual disintegration of activity in the hippocampus and septum, which provides evidence for impairment of the operation of the septo-hippocampal network during epileptogenesis.