title: Contralateral manual compensation for velocity-dependent force perturbations.
abstract: It is not yet clear how the temporal structure of a voluntary action is coded allowing coordinated bimanual responses. This study focuses on the adaptation to and compensation for a force profile presented to one stationary arm which is proportional to the velocity of the other moving arm. We hypothesised that subjects would exhibit predictive coordinative responses which would co-vary with the state of the moving arm. Our null hypothesis is that they develop a time-dependent template of forces appropriate to compensate for the imposed perturbation. Subjects were trained to make 500 ms duration reaching movements with their dominant right arm to a visual target. A force generated with a robotic arm that was proportional to the velocity of the moving arm and perpendicular to movement direction acted on their stationary left hand, either at the same time as the movement or delayed by 250 or 500 ms. Subjects rapidly learnt to minimise the final end-point error. In the delay conditions, the left hand moved in advance of the onset of the perturbing force. In test conditions with faster or slower movement of the right hand, the predictive actions of the left hand co-varied with movement speed. Compensation for movement-related forces appeared to be predictive but not based on an accurate force profile that was equal and opposite to the imposed perturbation.
authors.affiliation: Behavioural Brain Sciences, School of Psychology, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. c.p.jackson.1@bham.ac.uk
authors.forename: Carl P T
authors.initials: CP
authors.lastname: Jackson
authors.forename: R Chris
authors.initials: RC
authors.lastname: Miall
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena; D002490:Central Nervous System / Q000502:physiology; D005246:Feedback / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009483:Neuropsychological Tests; D010812:Physical Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors; D013998:Time Perception / Q000502:physiology