STUDIES OF EEG ACTIVITY OF LIMBIC STRUCTURES IN MAN

1. 1. Studies have been made of the on-going EEG activity of amygdala, hippocampus and hippocampal gyrus as recorded by implanted electrodes together with surface recordings in twenty-eight cases of temporal lobe epilepsy and two non-epileptic patients. 2. 2. A computer program has been used to determine the frequencies present in these limbic structures and elsewhere and to explore whether their wave processes share any common features. 3. 3. Strong correlations in several frequency bands were usually found between the hippocampus, hippocampal gyrus and ipsilateral amygdala. No contralateral coherences were found. 4. 4. These correlations were disrupted in stages of sleep which show slow wave or low voltage fast activity at the scalp. The wave characteristics of the limbic structures differ fundamentally in sleep from those of the scalp recordings. 5. 5. There is a stage of sleep in which marked spindling occurs in the limbic system without any representation of it at the convexity. 6. 6. Two conditions in which correlation, not usually present, are found to develop are during electrical seizure discharge in the limbic structures and after a pre-narcotic dose of barbiturates. © 1968.