UBC Theses and Dissertations
The relative contributions of the premotor and posterior parietal cortices to forward models of movement. Hermosillo, Robert Jeremiah Matthias
Producing smooth, coordinated movement may seem like a relatively simple process, but it actually requires a complex computational framework in order to reach accurately. It has been hypothesized that the brain predicts the sensory consequences of movement, and indeed, much research has laid down the theoretical framework for this process, however it is unclear how motor planning signals are used to determine the spatial configuration of the limbs. In this dissertation repetitive transcranial magnetic stimulation (rTMS) was applied to candidate sites in the fronto-parietal network to observe how this would affect decisions in a temporal order judgment (TOJ) task under stationary and moving conditions while participants were planning to cross their arms. Previous work has shown that under stationary conditions, error rates increase when participants have their arms in a crossed configuration or are simply planning to cross the arms. Under stationary conditions we observed an increase in TOJ error after rTMS was applied to the posterior parietal cortex (PPC), but not when it was applied to the dorsal premotor cortex (dPMC). However under moving conditions, rTMS caused a decreased in error rates when applied to either the dPMC or the PPC. By contrast, rTMS over a control site (area V4) resulted in no change in error rates under either stationary or moving conditions. Together, these 3 experiments suggest that predictions about the spatial consequences of limb movement use planning signals generated in the dPMC while limb spatial position information is generated within the PPC.
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