Learning and switching between stimulus-saccade associations in Parkinson’s disease

Hodgson, Timothy L. and Sumner, Petroc and Molyva, Dimitra and Sheridan, Ray and Kennard, Christopher (2013) Learning and switching between stimulus-saccade associations in Parkinson’s disease. Neuropsychologia, 51 (7). pp. 1350-1360. ISSN 0028-3932

Full content URL: http://dx.doi.org/10.1016/j.neuropsychologia.2013....

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Item Type:Article
Item Status:Live Archive

Abstract

Making flexible associations between what we see and what we do is important for many everyday tasks. Previous work in patients with focal lesions has shown that the control of saccadic eye movements in such contexts relies on a network of areas in the frontal cerebral cortex. These regions are reciprocally connected with structures in the basal ganglia although the contribution of these sub-cortical structures to oculomotor control in complex tasks is not well understood. We report the performance of patients with idiopathic Parkinsons disease (PDs) in a test which required learning and switching between arbitrary cue-saccade rules. In Experiment 1 feedback was given following each response which reliably indicated which of the two possible rules was correct. PDs were slower to learn the first cue-saccade association presented, but did not show increased error or reaction time switch costs when switching between two rules within blocks. In a follow up experiment the feedback given by the computer was adjusted to be probabilistic such that executing a response based upon the "correct" rule only resulted in positive feedback on 80% of trials. Under these conditions patients were impaired in terms of response latencies and number of errors. In all conditions PDs showed multi-stepping/hypometria of saccades consistent with a motoric deficit in executing actions based on cognitive cues. The findings are consistent with a role for the nigrostriatal dopamine system in the reinforcement of saccade-response-outcome associations. Intact performance of PDs when associations are not stochastically reinforced suggests that striatal learning systems are complemented by cognitive representations of task rules which are unaffected in the early stages of PD.

Keywords:Basal ganglia, Cognitive, Eye movements, Oculomotor, Task switching
Subjects:C Biological Sciences > C800 Psychology
Divisions:College of Social Science > School of Psychology
ID Code:10694
Deposited On:09 Jul 2013 15:53

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