title: Tricks of the mind: Visual hallucinations as disorders of attention.
abstract: Visual hallucinations are common across a number of disorders but to date, a unifying pathophysiology underlying these phenomena has not been described. In this manuscript, we combine insights from neuropathological, neuropsychological and neuroimaging studies to propose a testable common neural mechanism for visual hallucinations. We propose that 'simple' visual hallucinations arise from disturbances within regions responsible for the primary processing of visual information, however with no further modulation of perceptual content by attention. In contrast, 'complex' visual hallucinations reflect dysfunction within and between the Attentional Control Networks, leading to the inappropriate interpretation of ambiguous percepts. The incorrect information perceived by hallucinators is often differentially interpreted depending on the time-course and the neuroarchitecture underlying the interpretation. Disorders with 'complex' hallucinations without retained insight are proposed to be associated with a reduction in the activity within the Dorsal Attention Network. The review concludes by showing that a variety of pathological processes can ultimately manifest in any of these three categories, depending on the precise location of the impairment.
authors: Parkinson's Disease Research Clinic, Brain and Mind Research Institute, The University of Sydney, NSW, Australia. Electronic address: mac.shine@sydney.edu.au.
authors: James M
authors: JM
authors: Shine
authors: Parkinson's Disease Research Clinic, Brain and Mind Research Institute, The University of Sydney, NSW, Australia; Neuroscience Research Australia and the University of New South Wales, Sydney, NSW, Australia. Electronic address: c.ocallaghan@neura.edu.au.
authors: Claire
authors: C
authors: O'Callaghan
authors: Neuroscience Research Australia and the University of New South Wales, Sydney, NSW, Australia. Electronic address: g.halliday@neura.edu.au.
authors: Glenda M
authors: GM
authors: Halliday
authors: Parkinson's Disease Research Clinic, Brain and Mind Research Institute, The University of Sydney, NSW, Australia. Electronic address: simon.lewis@sydney.edu.au.
authors: Simon J G
authors: SJ
authors: Lewis
mesh_terms: D001288:Attention / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D006212:Hallucinations / Q000503:physiopathology*; D006801:Humans; D009434:Neural Pathways / Q000503:physiopathology; D014796:Visual Perception / Q000502:physiology*
keywords: Attentional Control Networks; Common neural mechanism; Default Mode Network; Dorsal Attention Network; Hallucinations; Ventral Attention Network