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Dawei W. Dong, Theodore G. Weyand, Bryan Payne, Jayaraman Rao; The role of the basal ganglia during free-viewing natural time-varying images. Journal of Vision 2004;4(8):654. doi: https://doi.org/10.1167/4.8.654.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: It is well-known that diseases in basal ganglia result in perturbations in ocular motor control. Whereas significant efforts have been invested in documenting many characteristics of oculomotor control in such patients, they have been largely restricted to laboratory tasks, i.e., tasks designed to characterize oculomotor parameters under conditions that are not representative of the conditions dictating eye movements in real life. In the current research, we study the role of the basal ganglia in gaze control under natural viewing conditions. Methods: We tracked the eye movements of Parkinsons Disease (PD) patients during free-viewing natural time-varying images. Among the PD patients we have access to are those that are receiving deep-brain stimulation (DBS) to the subthalamic nucleus and inner sector of the globus pallidus. We measured the statistics of eye movements in these individuals, with and without DBS, and compared them with normal controls, free-viewing the same natural time-varying images. Such experiments provide direct information on the involvement of the basal ganglia in gaze control. Results: The normal controls exhibit characteristic eye movements during free-viewing the natural time-varying images (Dong 2001, ARVO). When the DBS is turned on and properly adjusted, the eye movement statistics of PD patients are similar to controls. When the DBS is turned off, PD patients generate different eye movement statistics than controls. In particular, without DBS, PD patients initiate less number of saccades, generate smaller amplitude of saccades, and keep gaze near one location for a longer time. Conclusions: Under natural viewing conditions, the basal ganglia play a crucial role in regulating and perhaps initiating the saccadic eye movements. The statistics of the eye movements, including the fixation time and the number and the amplitude of saccades, might be used as sensitive indicators of PD status and the basal ganglia function.
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