PhD position

Oculomotor decision-making in health and Parkinson's disease

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With this project we aim at elucidating the pattern of deficits in sensorimotor decision-making in PD patients and healthy age-matched controls, addressing its multiple facets with novel oculomotor experiments.

Description

The PhD project below is part of NeuroSchool’s “International co-supervised PhD scholarships” call which will fund up to 54 months of research to be distributed among several co-supervised or co-directed PhD research projects.
APPLICATION MUST PROCEED THROUGH OUR WEBSITE: https://neuro-marseille.org/en/Calls/international-co-supervised-phd-scholarships/

International co-supervisor contact information

 

STATE OF THE ART : Voluntary eye movements provide a dynamic readout of ongoing perceptual and cognitive processes and they are often taken as a model of sensorimotor decision-making. Our two laboratories have previously investigated, both jointly and independently, the role of retinal and extraretinal (predictive and reward-related) information for gaze tracking behaviour (e.g Spering and Montagnini 2011), with a complementary approach, toward the clinical aspects for the UBC partner (Ming et al., 2016; Fooken et al., 2018) and the computational aspects for the AMU lab (Bogadhi et al. 2013, Damasse et al. 2018a, Pasturel et al. 2020). Parkinson’s Disease (PD) is mostly known for its dramatic effects on motor performance. However, few previous studies suggest that visual and memory-guided eye movements are largely spared in PD, whereas predictive eye movements undergo specific impairments (Helmchen et al. 2012). In addition, severe impairments in decision-related cognitive functions have been documented in PD patients (and related to their L-Dopa medication). For instance, their performance is suboptimal when they have to learn a probabilistic associative rule between a choice and the delivered reward, or when they have to learn a Prior about the occurrence of a perceptual feature (Perugini et al. 2018). Deficient frontal dopaminergic circuits are believed to be at the origin of several motor and cognitive impairments in PD. However, the evidence in this sense is multifaceted, with positive, negative and even null effects of dopamine abundance on specific PD-related deficits reported (Perugini et al. 2018), and typically addressed in independent, thus hardly comparable studies.

OBJECTIVES : With this project we aim at elucidating the pattern of deficits in sensorimotor decision-making in PD patients and healthy age-matched controls, addressing its multiple facets with novel oculomotor experiments. These experimental paradigms will globally target all aspects of decision behavior at once, including efficient use of prior experience, analysis of noisy sensory evidence, reward outcome-based correction, and choice selection under risk. Data will be analyzed and modeled within the theoretical framework of Bayesian statistical inference for decision-making (at AMU). Importantly, we will systematically correlate decision-making deficits with patients’ motor performance and with a number of clinical and neuropsychological assessments, with a particular focus on risk-taking behavior (at UBC, with clinical collaborators in Neurology). In addition, we will investigate the role of L-Dopa medication on the integration of experience-based information about contextual contingencies.

FEASABLITY : The feasibility of this project is high, as supported by the long-lasting collaboration of the partners, as well as by a set of preliminary results, obtained in a recent AMU-UBC study on visual target selection in presence of a stochastic target-reward association. These promising results were presented at international conferences (VSS and SfN; Damasse et al. 2018b; Montagnini et al., 2018). The first part of the PhD project will be devoted to finalizing and publishing this study. In a second time, the student will compare obtained results with data obtained in a new group of PD patients and a cohort of patients with schizophrenia, another documented dopaminergic dysfunction (Spering et al.; 2013; Bansal et al., 2018). To conclude, we expect that, by leveraging on a well-known sensorimotor system and on a high-resolution behavioral measure, this PhD project will shed new light on the multifaceted and yet poorly understood pattern of sensorimotor and cognitive deficits of Parkinson’s Disease.

Nature de finanement

NeuroSchool

Desired profile

The selected PhD student will design, implement and analyze a set of experiments to test eye movements and visual perception in Parkinson’s Disease patients, both ON and OFF medication, as well as in age-matched healthy controls and young healthy adults. She/he will also run simulations to fit the data with different decision models.

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