Acoustic and electrically elicited startle reaction: similar patterns of habituation and reflex modifications in humans

The present study was performed in order to verify two relevant phenomena related to Startle Reaction in normal subjects: 1) the response habituation, that consists of an exponential decrement of the R2 component of Blink Reflex after repeated identical stimuli, and 2) the modification of R1 magnitude, R2 magnitude and latency when the startle eliciting stimulus is preceded by a warning stimulus. Our data confirm: 1) that habituation is independent of paradigm and type of stimulation (acoustic vs electrocutaneous), and 2) an electrical prestimulus has a facilitatory effect on the R2 latency of the electrically elicited Blink Reflex onset with an inhibition of R2 magnitude. The present study support the view of a systemic supramodal central mechanism of information processing and sensorial gating with super-imposable effects on the different sensorial pathways.