Abnormal patterns of attentional network communication underlie visual hallucinations in Parkinson's disease
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1
The University of Sydney, Australia
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2
Neuroscience Research Australia, Australia
Introduction
Visual hallucinations are a common and devastating symptom of advanced Parkinson's disease (PD), however the mechanism underlying the disorder is poorly understood. Recently, we have proposed a novel hypothesis that suggests that visual hallucinations in PD are due to abnormal communication between attentional networks. In this study, we combined a novel task capable of eliciting visual hallucinations with fMRI to explore the neural basis of visual hallucinations using task-based functional connectivity.
Methods
3T BOLD data was collected from 21 patients with PD while they performed a visuoperceptual task, known as the Bistable Percept Paradigm, in which each individual suffered a high proportion of hallucinations (i.e. saw a 'hidden' image in a simple picture). Independent component analysis was used to extract 5 putative neural networks: the Dorsal Attention Network, the Default Mode Network, the Ventral Attention Network, the Medial Temporal Network and the Visual Network for functional connectivity analysis. Temporal derivatives were calculated for each network time course and were then multiplied together to create a functional coupling score for each network pair. We then explored the differences in functional coupling scores between hallucinations and normal perceptions.
Results
We observed an increase in connectivity between the Default Mode and the Medial Temporal Network in the early stages of a hallucination (t =2.2, p = 0.022), which was followed temporally by an increased coupling between the Default Mode and the Visual Network (t =2.7, p = 0.007). There was also a concomitant decrease in coupling between the Dorsal Attention and the Medial Temporal Network during visual hallucinations (t =2.6, p = 0.009).
Conclusions
Consistent with recent predictions, our results suggest that abnormal patterns of connectivity between attentional networks and those processing visual information lie at the core of visual hallucinations in Parkinson's disease.
Keywords:
Parkinson's disease,
functional MRI,
Visual hallucination,
Bistable Percept Paradigm,
Task-based functional connectivity
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Poster
Topic:
Sensation and Perception
Citation:
Shine
M,
O'Callaghan
C,
Muller
A,
Halliday
G and
Lewis
S
(2015). Abnormal patterns of attentional network communication underlie visual hallucinations in Parkinson's disease.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00351
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Dr. Mac Shine, The University of Sydney, Sydney, Australia, mac.shine@sydney.edu.au