Investigating the role of right parietal cortex in multistable perception using non-invasive brain stimulation [thesis]

Georg Schauer, University, My, University, My, Bartels, Andreas (Prof. Dr.)
Multistable perception describes the spontaneous fluctuation between two or more perceptual states when sensory input is ambiguous. An example hereof is bistability, which occurs when a stimulus has two competing interpretations that perceptually alternate over time. For instance, in structure- from-motion (SFM) bistable perception, the coherent movement of dots creates the illusion of a rotating sphere, where the direction of movement is uncertain. Another example is binocular rivalry (BR),
more » ... ch occurs when the two eyes are presented with dissimilar visual stimuli in the same retinal space, leading to an alternation of conscious awareness between the two stimuli. Multistable perception has been used to investigate the neural correlates of conscious experience, since an unchanging stimulus leads to a change in awareness, hence dissociating consciousness from sensory processing. Functional magnetic resonance imaging (fMRI) has consistently shown activity of the right intraparietal sulcus (IPS) and right superior parietal lobule (SPL) during perceptual transitions in multistable perception. Previously, transcranial magnetic stimulation (TMS) and in particular inhibitory theta burst stimulation (cTBS) has been used on the IPS to probe its causal role in multistable perception. That endeavour has produced inconsistent results on whether IPS inhibition shortens or lengthens multistable dominance durations. Problematically, the neural effects of cTBS over IPS during multistable perception are unknown, as is indeed the causal role of IPS in mediating perceptual reversals. Chapter 1 cTBS was applied over IPS or over vertex control site, between two sessions of fMRI, to illuminate the changes in neural activity accompanied by IPS cTBS. During the fMRI sessions, participants viewed alternating blocks of a bistable SFM stimulus or a replay condition using depth-cue disambiguated SFM. Behaviourally, it was found that IPS cTBS lengthened dominance durations when comparing pre vs post cTBS as well as when comparing IPS with v [...]
doi:10.15496/publikation-29158 fatcat:74z3yghxmnduvj7nouj34jycca