title: Preparing for a motor perturbation: early implication of primary motor and somatosensory cortices.
abstract: Although preparation of voluntary movement has been extensively studied, very few human neuroimaging studies have examined preparation of an intentional reaction to a motor perturbation. This latter type of preparation is fundamental for adaptive motor capabilities in everyday life because it allows a desired motor output to be maintained despite changes in external forces. Using fMRI, we studied how the sensorimotor cortical network is implicated in preparing to react to a mechanical motor perturbation. While maintaining a given wrist angle against a small force, subjects were instructed to prepare a reaction to a subsequent wrist angle displacement. This reaction consisted of, either resisting the imposed movement, or remaining passive. During the preparation of both reactions we found an early implication of M1 and S1 but no implication at all of the higher order motor area preSMA. This is clearly different from what has been found for voluntary movement preparation. These results show that the sensorimotor network activation during preparation of voluntary motor acts depends on whether one expects a motor perturbation to occur: when external forces can interfere with ongoing motor acts, the primary sensorimotor areas must be ready to react as quickly as possible to perturbations that could prevent the goal of the ongoing motor act from being achieved.
authors.affiliation: Mediterranean Institute of Cognitive Neuroscience, UMR 6193, CNRS-University of Aix-Marseille, Marseille, Cedex 20, France. degraaf@incm.cnrs-mrs.fr
authors.forename: Jozina B
authors.initials: JB
authors.lastname: de Graaf
authors.forename: Alexey
authors.initials: A
authors.lastname: Frolov
authors.forename: Michel
authors.initials: M
authors.lastname: Fiocchi
authors.forename: Bruno
authors.initials: B
authors.lastname: Nazarian
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Anton
authors.forename: Jean
authors.initials: J
authors.lastname: Pailhous
authors.forename: Mireille
authors.initials: M
authors.lastname: Bonnard
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D001931:Brain Mapping; D005246:Feedback / Q000502:physiology; D005260:Female; D006801:Humans; D007699:Kinesthesis / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009483:Neuropsychological Tests; D010812:Physical Stimulation; D011434:Proprioception / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*; D014836:Volition / Q000502:physiology*; D014955:Wrist Joint / Q000502:physiology; D055815:Young Adult