Electronic Thesis and Dissertation Repository


Master of Science




Heath, Matthew


The top-down nature of allocentric spatial representations (i.e., specifying target locations relative to other objects) is thought to render motor output via an offline mode of control. The present experiment tested this hypothesis by providing detailed trajectory analyses of allocentric and target-directed reaching tasks performed with and without concomitant limb vision. Allocentric tasks required reaches to a location defined by the relationship between a target and reference stimulus, whereas target-directed tasks required reaches directly to a target. Target-directed limb visible trials showed the most effective online trajectory amendments compared to their limb occluded counterparts and allocentric limb visible and occluded trials. Accordingly, I propose that target-directed reaches performed with limb vision are supported via ‘fast’ online visuomotor networks. In contrast, I propose that reaching in the absence of limb vision and/or to an allocentrically defined target is mediated via ‘slow’ offline visuoperceptual networks.

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Motor Control Commons