Fixational eye movements in Tourette syndrome
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Studies of saccadic eye movements in subjects with Tourette syndrome (TS) have provided additional evidence that there is a link between TS symptoms and deficits in fronto-striato-thalamic networks. These studies revealed impaired timing and inhibition of saccades. We compared fixational eye movements, such as microsaccades and ocular drifts, in subjects with TS and healthy controls.We measured horizontal and vertical eye positions with video-oculography in 14 subjects with Tourette syndrome. We found reduced microsaccade amplitude but increased time between adjacent microsaccades (intersaccadic interval). Hence, the rate of microsaccades was reduced in subjects with TS compared to controls. Measure of ocular stability during intersaccadic intervals revealed increased drift velocity and increased variance in eye position. We hypothesize that increased activity of the direct fronto-striatal pathway and the resulting reduction in basal ganglia outflow targeting the superior colliculus fixation zone affect the rate and amplitude of microsaccades in subjects with TS. The resulting impairment in frontal eye field fixation leads to increased drifts during intersaccadic interval in subjects with TS. Possible clinical implication for these results is that fixational eye movements can be objective biological markers of TS.
KeywordsMicrosaccades Gaze holding Vision Tics Basal ganglia
Compliance with ethical standards
The experiment protocol of this study complied with the tenets of the Declaration of Helsinki and was approved by the Emory University Institutional Review Board.
AS is supported by grant from Dystonia Medical Research Foundation and Dystonia Coalition. The authors have no financial conflicts related to the contents included in this manuscript.
- 16.J. Otero-Millan, X.G. Troncoso, S.L. Macknik, I. Serrano-Pedraza, S. Martinez-Conde, Saccades and microsaccades during visual fixation, exploration, and search: foundations for a common saccadic generator, J Vis 8(14) (2008) 21 1–18Google Scholar
- 17.M. Rolfs, R. Kliegl, R. Engbert, Toward a model of microsaccade generation: the case of microsaccadic inhibition, J Vis 8(11) (2008) 5 1–23Google Scholar
- 29.W.K. Goodman, L.H. Price, S.A. Rasmussen, C. Mazure, P. Delgado, G.R. Heninger, D.S. Charney, The Yale-Brown Obsessive Compulsive Scale. II. Validity, Arch Gen Psychiatry 46(11) (1989) 1012–6Google Scholar
- 38.Ghasia FF, Shaikh AG (2015) Uncorrected myopic refractive error increases microsaccade amplitude. Invest Ophthalmol Vis SciGoogle Scholar