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dc.contributor.authorSadeghi, Mohsen
dc.date.accessioned2018-08-02T13:18:42Z
dc.date.available2018-08-02T13:18:42Z
dc.date.issued2018-07-31
dc.date.submitted2018-01-03
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/278611
dc.description.abstractHuman sensorimotor control is remarkably adept at utilising contextual information to learn and recall systematic sensorimotor transformations. Here, we investigate the motor representations that underlie such learning, and examine how motor memories acquired based on different contextual information interact. Using a novel three-dimensional robotic manipulandum, the 3BOT, we examined the spatial transfer of learning across various movement directions in a 3D environment, while human subjects performed reaching movements under velocity-dependent force field. The obtained pattern of generalisation suggested that the representation of dynamic learning was most likely defined in a target-based, rather than an extrinsic, coordinate system. We further examined how motor memories interact when subjects adapt to force fields applied in orthogonal dimensions. We found that, unlike opposing fields, learning two spatially orthogonal force fields led to the formation of separate motor memories, which neither interfered with nor facilitated each other. Moreover, we demonstrated a novel, more general aspect of the spontaneous recovery phenomenon using a two-dimensional force field task: when subjects learned two orthogonal force fields consecutively, in the following phase of clamped error feedback, the expression of adaptation spontaneously rotated from the direction of the second force field, towards the direction of the first force field. Finally, we examined the interaction of sensorimotor memories formed based on separate contextual information. Subjects performed reciprocating reaching and object manipulation tasks under two alternating contexts (movement directions), while we manipulated the dynamics of the task in each context separately. The results suggested that separate motor memories were formed for the dynamics of the task in different contexts, and that these motor memories interacted by sharing error signals to enhance learning. Importantly, the extent of interaction was not fixed between the context-dependent motor memories, but adaptively changed according to the task dynamics to potentially improve overall performance. Together, our experimental and theoretical results add to the understanding of mechanisms that underlie sensorimotor learning, and the way these mechanisms interact under various tasks and different dynamics.
dc.description.sponsorshipThe thesis was funded by Wellcome Trust and the Yousef Jameel scholarship via Cambridge Trust.
dc.language.isoen
dc.rightsAll rights reserved
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectSensorimotor learning
dc.subjectForce field adaptation
dc.subjectGeneralisation of learning
dc.subjectSpontaneous recovery
dc.subjectMotor control
dc.subjectAdaptive coupling
dc.subjectReaching movements
dc.subjectObject manipulation
dc.subjectState-space models
dc.subjectReciprocal movements
dc.titleRepresentation and Interaction of Sensorimotor Learning Processes
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentEngineering
dc.date.updated2018-07-31T10:36:06Z
dc.identifier.doi10.17863/CAM.25951
dc.publisher.collegeRobinson College
dc.type.qualificationtitlePhD in Engineering
cam.supervisorWolpert, Daniel
cam.thesis.fundingfalse
rioxxterms.freetoread.startdate2018-07-31


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