MODULATION OF SPINAL REFLEXES - AROUSAL, PLEASURE, ACTION

The human startle reflex is reliably modulated by the affective valenc e of foreground pictures, with larger reflexes elicited when viewing u npleasant relative to pleasant scenes. If this modulation is due to pr iming of the defensive startle reflex by an aversive foreground, a dif ferent pattern should occur for a reflex that is not inherently defens ive in nature. In the current study, affective modulation was investig ated using the spinal tendinous (T) reflex, which is well documented a s sensitive to differences in arousal and is involved in actions that are both appetitively and defensively motivated. As such, T reflexes e licited during unpleasant pictures were not expected to be augmented r elative to those elicited in the context of pleasant pictures. Results showed that T reflexes were facilitated during processing of arousing stimuli-either pleasant or unpleasant relative to low-arousal neutral materials. These effects of emotional stimuli on T-reflex amplitude a re consistent with the hypothesis that motivational priming underlies affective reflex modulation.