Perceptual Decision Making Under Conditions of Visual Uncertainty

Plain-language summary

In this proposal the investigators have three Specific Aims using human patient populations as model systems; 1) identify a role for the Basal Ganglia (BG) in perceptual decision making; 2) determine whether the Basal Ganglia contribute to decision making under conditions of visual uncertainty; 3) determine whether the cerebellum plays a role in perceptual decision-making under conditions of visual uncertainty. The investigators designed experiments using healthy humans and humans with diseases known to affect the Basal Ganglia and the cerebellum, Parkinson's Disease, dystonia and non-dystonic cerebellar damage. With this approach the investigators will test the following hypotheses: 1) Patients with Parkinson's Disease and dystonia will have more difficulty than healthy controls making perceptual decisions when faced with sensory uncertainty; when sensory information is certain, patients will show improved decision-making but will still be impaired relative to healthy humans. Hypothesis 2: If ambiguous sensory information is aided by prior information, patients with Parkinson's Disease and dystonia will be unable to use the prior (bias/memory) information to inform their decisions. Hypothesis 3: Deep Brain Stimulation (DBS) of Basal Ganglia structures will improve the ability of patients to use prior information to inform their decisions when faced with sensory uncertainty. Hypothesis 4: Both cholinergic and dopaminergic medical therapies will improve the ability of patients to use prior information to inform their decisions. Hypothesis 5: Patients with non-dystonic cerebellar damage will be similar to healthy controls in performance of a perceptual decision making task in conditions of visual uncertainty. The overarching framework of this application is that the same mechanisms (D1 striatal synaptic plasticity) that operate in reward learning play a role in learning and using stimulus priors in a perceptual decision-making task when faced with uncertainty. Because Parkinson's Disease and dystonia share deficits in striatal circuitry, the patient deficits on this task will be similar. Because non-dystonic cerebellar patients do not have dysfunction of striatal circuits, they will show no deficits in the ability to use stimulus priors to guide choices in uncertain conditions. In the event these patients do show deficits, this is will provide evidence for an unexplored role for the cerebellum in perceptual decision-making.

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