Behavioural manipulations of Parietal lobe function

The aim of this thesis was to develop a novel behavioural technique to disrupt parietal function in order to induce top-down cortical modulation of low-level brain structures, namely the brainstem mediated vestibuloocular reflex and the early visual cortex. The premise of the technique was based upon using stimuli that engaged overlapping neuronal networks. To this end, we employed a technique that involved concurrent vestibular activation and viewing of bistable perceptual visual stimuli or performing visualised spatial attention tasks. The thesis presents data that shows the ability of this technique to induce a handedness related cortical modulation of the vestibulo-ocular reflex and modulation of the early visual cortex. Subsequently we applied trans-cranial direct stimulation to directly disrupt parietal inter-hemispheric balance in order to induce an asymmetrical modulation of the VOR and propose a revised computational model for vestibular processing. The results from these experiments present the first behavioural demonstration that vestibular cortical processing is strongly lateralised to the non-dominant hemisphere. We propose that this technique developed and validated in this thesis can be used to further probe and investigate cognitive parietal function such as numerical cognition and human decision making.