Electroconvulsive therapy (ECT) involves the use of electrical stimulation to elicit a series of generalized tonic-clonic seizures for therapeutic purposes and is the most effective treatment known for major depression. These treatments have significant effects on neurophysiology, many of which are manifest in the electroencephalogram (EEG). The relationship between EEG data and the response to electroconvulsive therapy (ECT) has been studied since the 1940's but for many years no consistent correlates were found. Recent studies indicate that a number of specific EEG features recorded during the induced seizures (ictal EEG) as well as before and after a course of treatment (inter-ictal EEG) are related to both the therapeutic efficacy and cognitive side-effects.

Similar to ECT, repetitive transcranial magnetic stimulation (rTMS), which involves focal electromagnetic stimulation of cortical neurons, has also been studied as an antidepressant therapy and appears to have effects on neurophysiology. Given the similarity of these treatments it is natural to consider whether advances in understanding the electrophysiologic correlates of the ECT response might have implications for rTMS. The present paper reviews the literature on the EEG effects of ECT and discusses the implications in terms of the likely efficacy and side-effects associated with rTMS in particular locations, the potential of eliciting an antidepressant response without eliciting a seizure or through eliciting a focal seizure with rTMS, and the possibility of using rTMS to inhibit and therefore protect specific brain regions during therapeutic generalized seizure induction.

Keywords: ECT, EEG, rTMS, Major Depression

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