STARTLE POTENTIATION - SHOCK SENSITIZATION, AVERSIVE LEARNING, AND AFFECTIVE PICTURE MODULATION

This study investigated the size of, and relationship between, differe nt modulatory effects of aversive stimulation on the acoustic startle reflex. This reflex is potentiated by shock exposure and associative s hock conditioning (in animals and human volunteers) and unpleasant pic tures (tin human volunteers). In this study, dramatic sensitization of the probe-startle response was observed after shock exposure but not after a control task. Magnitude of sensitization was significantly lar ger than associative shock conditioning and picture modulation effects (also significant). Sensitization and conditioning scores showed mode st, significant correlations with one another but not with picture mod ulation scores, consistent with animal data showing that partially ove rlapping brain mechanisms (i.e., amygdaloid-reticular projections) med iate these effects. The present results also indicate that sensitizati on of startle in human volunteers is a relatively more robust defensiv e response to aversive stimulation.