title: Effects of motor intention on the perception of somatosensory events: a behavioural and functional magnetic resonance imaging study.
abstract: The intention to execute a movement can modulate our perception of sensory events, and this modulation is observed ahead of both ocular and upper limb movements. However, theoretical accounts of these effects, and also the empirical data, are often contradictory. Accounts of "active touch", and the premotor theory of attention, have emphasized how movement intention leads to enhanced perceptual processing at the target of a movement, or on the to-be-moved effector. By contrast, recent theories of motor control emphasize how internal "forward" model (FM) estimates may be used to cancel or attenuate sensory signals that arise as a result of self-generated movements. We used behavioural and functional brain imaging (functional magnetic resonance imaging, fMRI) to investigate how perception of a somatosensory stimulus differed according to whether it was delivered to a hand that was about to execute a reaching movement or the alternative, nonmoving, hand. The results of our study demonstrate that a somatosensory stimulus delivered to a hand that is being prepared for movement is perceived to have occurred later than when that same stimulus is delivered to a nonmoving hand. This result indicates that it takes longer for a tactile stimulus to be detected when it is delivered to a moving limb and may correspond to a change in perceptual threshold. Our behavioural results are paralleled by the results of our fMRI study that demonstrated that there were significantly reduced blood-oxygen-level-dependent (BOLD) responses within the parietal operculum and insula following somatosensory stimulation of the hand being prepared for movement, compared to when an identical stimulus was delivered to a nonmoving hand. These findings are consistent with the prediction of FM accounts of motor control that postulate that central sensory suppression of somatosensation accompanies self-generated limb movements, and with previous reports indicating that effects of sensory suppression are observed in higher order somatosensory regions.
authors.affiliation: School of Psychology, University of Nottingham, UK. Stephen.jackson@nottingham.ac.uk
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Jackson
authors.forename: Amy
authors.initials: A
authors.lastname: Parkinson
authors.forename: Sally L
authors.initials: SL
authors.lastname: Pears
authors.forename: Se-Ho
authors.initials: SH
authors.lastname: Nam
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006225:Hand / Q000294:innervation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D033182:Intention; D007600:Judgment / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009068:Movement / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010812:Physical Stimulation / Q000379:methods; D013003:Somatosensory Cortex / Q000098:blood supply* / Q000502:physiology*; D013997:Time Factors; D055698:Touch Perception / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen