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Eirini Mavritsaki, Glyn Humphreys; Different functional roles of dopamine and acetylcholine in visual selection: Simulations of visual search in Alzheimer’s and Parkinson’s Diseases.. Journal of Vision 2013;13(9):523. doi: https://doi.org/10.1167/13.9.523.
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Previous research has differentiated between the performance of Parkinson’s and Alzheimer’s disease patients in visual search task [1, 2]. While Alzheimer’s patients show normal (parallel) search for feature targets, performance is impaired for conjunction targets. Parkinson’s patients can show the opposite pattern. These deficiencies may relate to deficiencies in acetylcholine for Alzheimer’s patients and dopamine for Parkinson’s patients, though both forms of deficiency exist in both disorders. We examined the effects of altering these neurotransmitters through computational modelling using the spiking Search over Space and Time (sSoTS) framework previously used to simulate behavioural and fMRI data on visual search, along also with the effects of posterior parietal cortex damage [3, 4]. To simulate Alzheimer’s disease we applied changes in the model based on acetylcholine depletion . For Parkinson’s disease we altered parameters responsible for dopamine depletion  . Using these changes, the model was able to simulate the double dissociation between feature and conjunction search. Simulated reductions in dopamine led to a loss of search guidance to salient targets whilst reductions in acetylcholine affected the ability to reject competing distractors. The results point to particular functional roles of the different neurotransmitters in visual selection. REFERENCES 1. Cormack, F., et al., International Journal of Geriatric Psychiatry, 2004. 19(8): p. 763-772. 2. Cossa, F.M., S. Dellasala, and H. Spinnler, Neuropsychologia, 1989. 27(6): p. 887-892. 3. Mavritsaki, E., et al., Psychological Review, 2011. 118(1): p. 3-41. 4. Mavritsaki, E., et al., Cognitive Neuropsychology, 2009. 26(4): p. 343-390. 5. Deco, G. and A. Thiele, European Journal of Neuroscience, 2009. 30(3): p. 347-354. 6. Rolls, E.T., et al., Nature Reviews Neuroscience, 2008. 9(9): p. 696-709.
Meeting abstract presented at VSS 2013
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