STARTLE REFLEX AND EMOTION MODULATION IMPAIRMENT AFTER A RIGHT AMYGDALA LESION

In the present study, startle responses during resting states as well as during the presentation of a set of emotive slides were recorded fr om a 32-year-old male patient with a rare localized lesion of the righ t amygdala. The startle reflex is a response modulated by affective st ates: it has been reliably used in the literature to measure the avers iveness of emotive stimuli. The animal literature has shown that the c ircuit of this reflex is directly influenced by amygdala projections. The startle responses of the patient were compared with those of eight age-matched normal subjects. The patient's startle amplitudes showed an overall impaired response and an inhibited reflex contralateral to the lesion. In addition, he failed to show the typical star-tie potent iation induced by an aversive emotive background. The data confirm, in the human, previous results from the literature in other species on a mygdala involvement in startle and emotional responses. Furthermore, t he observation of the importance of the right amygdala in the modulati on of emotion is consistent with the hypothesis of right hemisphere sp ecialization for aversive emotions. The results are discussed in the c ontext of the literature on human amygdala lesions.