MODIFICATION OF THE ELECTRICALLY ELICITED EYEBLINK BY ACOUSTIC, VISUAL, AND VIBROTACTILE PULSES

The purpose of the present research was to investigate the cross-modal integration of sensory information in the blink reflex circuit. In th ree experiments, the eyeblink reflex was elicited by an electrical pul se to the forehead in college students. Weak pulses were acoustic in E xperiment 1 (N = 28), visual in Experiment 2 (N = 17), and vibrotactil e in Experiment 3 (N = 17). The R2 component of the electrically elici ted eyeblink reflex was facilitated by weak acoustic pulses that were presented at the same time as or shortly after the electrical stimulus . A weak visual pulse also facilitated the blink reflex, but only when visual pulse onset preceded or occurred simultaneously with the elect rical stimulus. Vibrotactile pulses presented to the hand did not caus e facilitation at any interval. Weak pulses in all three sensory modal ities presented before the blink-eliciting stimulus were able to inhib it the eyeblink reflex. These results suggest that the temporal summat ion that leads to facilitation of the blink response by weak stimuli o ccurs at a common location at which electrical, acoustic, and visual, but not vibrotactile, information converges. These data also show that facilitation and inhibition of the blink response are based on differ ent underlying mechanisms.