On the synchronisation of neural oscillations during gestalt perception, it's relation to visual hallucinations in psychiatric and neurological diseases and what is causing them

Abstract

Visual hallucinations are a cause of great distress in several psychiatric and neurological diseases. Sadly, still little is known about the aetiology of visual hallucinations. An interesting hypothesis suggests that hallucinations are the result of perception being dominated by top-down processes, for which ample evidence is provided with respect to schizophrenia. However, studies with respect to other diseases such as Parkinsons disease and Lewy-body dementia are scarce. Furthermore, what causes top-down processes to dominate perception requires more investigation as well. We aim to elucidate the role of top-down and bottom-up processes in causing hallucinations by investigating neural synchronisation during gestalt processing in schizophrenia, Parkinsons disease and Lewy-body dementia. In addition we will assess the effects of ketanserin on neural synchronisation. Also, we will investigate the role of functional and anatomical thalamocortical connectivity in the occurrence of deviant neural synchronisation and visual hallucinations. Finally we will also assess the role of thalamic GABA and glutamate levels in neural synchronisation and visual hallucinations. The results of this study provides us with a better understanding of what causes top-down processes to dominate the perceptual domain, paving the way for the development of better treatments.