scholarly journals Visual Hallucinations Are Characterized by Impaired Sensory Evidence Accumulation: Insights From Hierarchical Drift Diffusion Modeling in Parkinson’s Disease

2017 ◽  
Vol 2 (8) ◽  
pp. 680-688 ◽  
Author(s):  
Claire O’Callaghan ◽  
Julie M. Hall ◽  
Alessandro Tomassini ◽  
Alana J. Muller ◽  
Ishan C. Walpola ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Visual Hallucinations ◽  
Diffusion Modeling ◽  
Drift Diffusion ◽  
Evidence Accumulation ◽  
Sensory Evidence

scholarly journals Accumulation of sensory evidence is impaired in Parkinson’s disease with visual hallucinations

2017 ◽  
Author(s):  
Claire O’Callaghan ◽  
Julie M. Hall ◽  
Alessandro Tomassini ◽  
Alana J. Muller ◽  
Ishan C. Walpola ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Sensory Processing ◽  
Sensory Input ◽  
Decision Time ◽  
Visual Hallucinations ◽  
Top Down ◽  
Evidence Accumulation ◽  
Sensory Evidence ◽  
Response Output

AbstractModels of hallucinations across disorders emphasise an imbalance between sensory input and top-down influences over perception. However, the psychological and mechanistic correlates of this imbalance remain underspecified. Visual hallucinations in Parkinson’s disease (PD) are associated with impairments in lower level visual processes and attention, accompanied by over activity and connectivity in higher-order association brain networks. PD therefore provides an attractive framework to explore the relative contributions of bottom-up versus top-down disturbances in hallucinations. Here, we characterised sensory processing in PD patients with and without visual hallucinations, and in healthy controls, by fitting a hierarchical drift diffusion model (hDDM) to an attentional task. The hDDM uses Bayesian estimates to decompose reaction time and response output into parameters reflecting drift rates of evidence accumulation, decision thresholds and non-decision time. We observed slower drift rates in PD patients with hallucinations, which were insensitive to changes in task demand. In contrast, wider decision boundaries and shorter non-decision times relative to controls were found in PD regardless of hallucinator status. Inefficient and less flexible sensory evidence accumulation emerge as unique features of PD hallucinators. We integrate these results with current models of hallucinations, suggesting that slow and inefficient sensory input in PD is less informative, and may therefore be down-weighted leading to an over reliance on top-down influences. Our findings provide a novel computational framework to better specify the impairments in dynamic sensory processing that are a risk factor for visual hallucinations.

Effects of rivastigmine in patients with and without visual hallucinations in dementia associated with Parkinson's disease

2006 ◽  
Vol 21 (11) ◽  
pp. 1899-1907 ◽  
Author(s):  
David Burn ◽  
Murat Emre ◽  
Ian McKeith ◽  
Peter Paul De Deyn ◽  
Dag Aarsland ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Visual Hallucinations

Psychotic and Depressive Symptoms in Parkinson's Disease a Study of the Growth Hormone Response to Apomorphine

1995 ◽  
Vol 167 (4) ◽  
pp. 522-526 ◽  
Author(s):  
John D. C. Mellers ◽  
Niall P. Quinn ◽  
Maria A. Ron
Keyword(s):  
Parkinson’S Disease ◽  
Growth Hormone ◽  
Parkinson's Disease ◽  
Depressive Symptomatology ◽  
Past History ◽  
Visual Hallucinations ◽  
Hormone Response ◽  
Receptor Sensitivity ◽  
Dopaminergic Mechanisms ◽  
History Of

BackgroundThe growth hormone (GH) response to apomorphine, thought to reflect central dopaminergic receptor sensitivity, has been reported as enhanced in acute schizophrenia. We investigated this response in relation to the psychotic episodes associated with Parkinson's disease (PD).MethodThe GH response to apomorphine was measured in three groups of patients with Parkinson's disease: those currently psychotic (n = 9), those with a past history of psychosis (n = 7) and those who had never been psychotic (n = 8).ResultsApomorphine-induced GH response was not related to psychosis but was unexpectedly associated with measures of depression.ConclusionsVisual hallucinations were a prominent feature in the psychotic patients and the atypical nature of these psychoses might explain why we found no evidence of dopaminergic sensitivity. Serotonergic dysfunction would be in keeping with this. Dopaminergic mechanisms may contribute to the minor depressive symptomatology seen in PD.

Visual hallucinations and illusions in Parkinson’s disease: the role of ocular pathology

2020 ◽  
Author(s):  
Ana Marques ◽  
Steven Beze ◽  
Bruno Pereira ◽  
Carine Chassain ◽  
Nathalie Monneyron ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Visual Hallucinations ◽  
Ocular Pathology
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