City Research Online

Abstract

The blink reflex elicited by the electrical stimulation of the median nerve at the wrist (hand blink reflex, HBR) is a subcortical, defensive response that is enhanced when the stimulated hand is inside the peripersonal space of the face. Such enhancement results from a tonic, topdown modulation of the excitability of the brainstem interneurons mediating the HBR. Here we aim to (1) characterize the somatotopical specificity of this top down modulation and (2) investigate the effect of cognitive expectations on such modulation. Experiment 1 showed that the somatotopical specificity of the HBR enhancement is not only heterosegmental, but also partially homosegmental, i.e. the enhancement is greater for the HBR elicited by stimulation of the hand located inside the peripersonal space of the face, as compared to the HBR elicited by the stimulation of the other hand, always kept far from the face. Experiment 2 showed that the top-down modulation of the HBR is triggered only when the participants expect to receive stimuli on the hand placed inside the peripersonal space of the face, and is
thus strongly dependent on cognitive expectations. Taken together, these findings indicate a fine somatotopical and cognitive tuning of the excitability of brainstem circuits subserving the HBR, whose strength is adjusted depending on the context in a purposeful manner.

Publication Type:	Article
Publisher Keywords:	brainstem reflexes, cortical modulation, cognitive expectations, somatotopy, peripersonal space.
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
Departments:	School of Health & Psychological Sciences > Psychology
SWORD Depositor:	Symplectic Administrator

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