[Activation motor response in depressive states. Changes in the Hoffmann reflex during psychomotor testing]

Psychophysiological response of activation was explored both in control and depressed patients before and after antidepressant treatment. Hoffmann reflex (H reflex) and heat rate were recorded. Two psychomotor tests were studied in order to modify the level of vigilance. Control subjects had two different psychophysiological responses: slight increase of cardiac rhythm together with facilitation of H reflex or marked increase of cardiac rhythm associated with inhibition of H reflex. Depressed patients always showed an increase in H reflex during each task. H reflex was reduced only when patient recovered after a period of treatment. In both populations, heart rate for a given test was modified in the same way. Results are discussed in the light of the existence of two different activating systems. In depressed patients the lack of inhibition of H reflex could be explained by the decrease of initial arousal.