HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 574/2/367    most recent jphysiol.2005.103697v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Klam, F. Articles by Graf, W. Search for Related Content PubMed PubMed Citation Articles by Klam, F. Articles by Graf, W. Related Collections Neuroscience

¹ Laboratoire de Physiologie de la Perception et de l'Action, CNRS/Collège de France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France

An important prerequisite for effective motor action is the discrimination between active and passive body movements. Passive movements often require immediate reflexes, whereas active movements may demand suppression of the latter. The vestibular system maintains correct body and head posture in space through reflexes. Since vestibular inputs have been reported to be largely suppressed in the vestibular nuclei during active head movements, we investigated whether head movement-related signals in the primate parietal cortex, a brain region involved in self-motion perception, could support both reflex functions and self-movement behaviour. We employed a paradigm that made available direct comparison of neuronal discharge under active and passive movement conditions. In this study, we demonstrate that a population of intraparietal (VIP (ventral) and MIP (medial)) cortex neurons change their preferred directions during horizontal head rotations depending on whether animals have performed active movements, or if they were moved passively. In other neurons no such change occurred. A combination of these signals would provide differential information about the active or passive nature of an ongoing movement. Moreover, some neurons' responses clearly anticipated the upcoming active head movement, providing a possible basis for vestibular-related reflex suppression. Intraparietal vestibular neurons thus distinguish between active and passive head movements, and their responses differ substantially from those reported in brainstem vestibular neurons, regarding strength, timing, and direction selectivity. We suggest that the contextual firing characteristics of these neurons have far-reaching implications for the suppression of reflex movements during active movement, and for the representation of space during self-movement.

(Received 15 December 2005; accepted after revision 16 March 2006; first published online 23 March 2006)
Corresponding author W. M. Graf: Department of Physiology & Biophysics, Numa P.G. Adams Building, Howard University College of Medicine, 520 W Street N.W., Washington, DC 20059, USA. Email: wgraf{at}howard.edu

This article has been cited by other articles:

				V. Marlinski and R. A. McCrea Activity of Ventroposterior Thalamus Neurons During Rotation and Translation in the Horizontal Plane in the Alert Squirrel Monkey J Neurophysiol, May 1, 2008; 99(5): 2533 - 2545. [Abstract] [Full Text] [PDF]