Abstract Electrical stimulation of the median nerve at the wrist may elicit a blink reflex (hand blink reflex (HBR)) mediated by a neural circuit at brain stem level. As, in a Sherringtonian sense, the blink reflex is a defensive response, in a series of experiments we tested, in healthy volunteers, whether and how the HBR is modulated by the proximity of the stimulated hand to the face. Electromyographic activity was recorded from the orbicularis oculi , bilaterally. We observed that the HBR is enhanced when the stimulated hand is inside the peripersonal space of the face, compared with when it is outside, irrespective of whether the proximity of the hand to the face is manipulated by changing the position of the arm ( experiment 1 ) or by rotating the head while keeping the arm position constant ( experiment 3 ). Experiment 2 showed that such HBR enhancement has similar magnitude when the participants have their eyes closed. Experiments 4 and 5 showed, respectively, that the blink reflex elicited by the electrical stimulation of the supraorbital nerve, as well as the N20 wave of the somatosensory evoked potentials elicited by the median nerve stimulation, are entirely unaffected by hand position. Taken together, our results provide compelling evidence that the brain stem circuits mediating the HBR in humans undergo tonic and selective top-down modulation from higher order cortical areas responsible for encoding the location of somatosensory stimuli in external space coordinates. These findings support the existence of a “defensive” peripersonal space, representing a safety margin advantageous for survival. body posture brain stem circuits cortex space representation Footnotes Copyright © 2012 the American Physiological Society « Previous | Next Article » Table of Contents This Article Published online before print November 2011 , doi: 10.​1152/​jn.​00731.​2011 AJP - JN Physiol February 2012 vol. 107 no. 3 880-889 » Abstract Free Full Text Free to you Full Text (PDF) Free to you All Versions of this Article: jn.00731.2011v1 107/3/880 most recent Classifications Article Services Email this article to a friend Alert me when this article is cited Alert me if a correction is posted Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Download to citation manager Citing Articles Load citing article information Citing articles via Web of Science Google Scholar Articles by Sambo, C. F. Articles by Iannetti, G. D. PubMed PubMed citation Articles by Sambo, C. F. Articles by Iannetti, G. D. Related Content Load related web page information Current Issue February 2012, 107 (3) Alert me to new issues of AJP - JN Physiol About the Journal Information for Authors Submit a Manuscript Ethical Policies AuthorChoice PubMed Central Policy Reprints and Permissions Advertising Press Copyright © 2012 the American Physiological Society Print ISSN: 0022-3077 Online ISSN: 1522-1598 var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); var pageTracker = _gat._getTracker("UA-2924550-1"); pageTracker._trackPageview();

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