UBC Theses and Dissertations
Adaptations in visual and proprioceptive processing following short- and long-term visual deprivation Bourns, Karen Elizabeth
While significant cortical plasticity is known to take place during prolonged visual deprivation, little is known about adaptation to acute onset vision loss. Here, we use a two-experiment study to investigate adaptations in processing visual and proprioceptive information in acute onset vision loss. Experiment I: Visual input was removed for 2 hours to simulate acute onset short-term vision loss. Participants performed 80 trials of a reaching and grasping task pre- and post-deprivation (160 trials). Proprioceptive control (No-Vision) was used for the first 40 trials, followed by 40 trials using visual control (Vision). In all trials participants grasped a circular target in response to an auditory tone. Prior to the initiation of each trial, the subject’s arm was passively moved to the target location and returned to the start position by an experimenter. Kinematic measurements (e.g. limb position, grip aperture) were obtained using 3 infrared markers (thumb, forefinger, and wrist) and an OptoTrak Certus (Northern Digital, Inc.). Experiment II: On the Experimental day, Visual input was removed for 8 hours to simulate acute onset long-term vision loss. During the 8-hr deprivation, participants performed normal daily activities with the assistance of an experimenter. On the control day, participants performed these same activities with full vision. Pre- and post each 8 hour period participants performed the same grasping task as Experiment I. In addition to the grasping task, participants completed an oddball detection task following the grasping task. Somatosensory and visual evoked potentials were recorded in response to tactile and visual stimuli. Both tasks involved detecting stimulus onset to either the right or left index finger. Results of both experiments suggest a dual-phase adaptation: improving on movement speed rather than corrective capacity in early adaptation, and favouring planning more proprioceptively accurate movements later in adaptation.
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Attribution-NonCommercial-NoDerivs 2.5 Canada