<p>Trajectory formation is an important quality of human movement wherein the analysis of its kinematic structure often permits inferences regarding the underlying sensorimotor organization. The studies reported herein aimed to reveal how task-specific encoding of saccades contribute to two movement models. We first examined saccades for changes in the evidence for online spatial corrections in response to different instances of visual tracking. Results from our first study indicated the sensorimotor operations associated with making timed series responses permitted unhindered operation of online corrections in predictive saccades. These saccades imposed a demand on spatial working memory without suffering diminished corrections typical of single delayed memory-guided saccades. Next, we queried the role of ventral stream visuomotor processing, as well as the contribution of basic stimulus features to explaining known modulations of online saccadic corrections. Our results are consistent with the explanation that ventral stream contribution to target metrics influence trajectory kinematics, but did not induce diminished online corrections if vision of that illusory target was available at saccade onset. Using another movement task, we examined how different saccadic tracking behaviours dissociated the contribution of various sensorimotor operations involved in oculomotor preparation and execution to eye-hand coupling. By observing changes in manual trajectory in an oculo-manual task, we contrasted the effects of saccadic tracking in predictive and reactive modes, overt and covert, horizontal and vertical, spatially congruent or perpendicular axes of primary motion relative to eye-hand coupling. From these data we concluded that saccadic encoding induced execution-dependent coupling, and optionally motor planning-dependent coupling when task constraints specified temporal synchrony between eye and hand movements. Moreover, eventual motor execution was a prerequisite for the emergence of oculomotor planning-dependent coupling effects. This implied no apparent contribution to the coupling dynamic as an exclusive function of shifts in the spatial allocation of attention without oculomotor output.</p> / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/13487 |
| Date | 10 1900 |
| Creators | Richardson, Brian A. |
| Contributors | Lyons, Jim, Neuroscience |
| Source Sets | McMaster University |
| Detected Language | English |
| Type | dissertation |
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