Eye/ Hand Coordination in Tourette Syndrome

Grant Type
Grant Year
Institution Location
Institution Organization Name
Queens University Canada
Investigators Name
Munoz, Douglas, PhD

A key issue in TS research is whether tic movements are unintentional motor responses or, in some measure, are purposefully executed movements. However, few studies have examined and compared the similarities and differences between these two types of behaviors in a measurable way. If we are to understand the control mechanisms underlying voluntary movements and motor tics, such quantitative studies using well-defined movement tasks are essential. Moreover, systematic and quantitative studies are of critical importance for the assessment of medications and, ultimately, the development of animal models. The main goal of this research is to develop critical behavioral tasks involving voluntary movements and tics in TS patients. By understanding voluntary movements and tic behavior we can then learn about the underlying neural circuitry and assess, in subtle detail, the effectiveness of treatments for TS. Our approach is unique in that we will bring rigorous quantitative analysis of complex motor behavior to the study of TS subjects. We will examine individuals with TS and age-matched control subjects in several different types of experiments that are designed to assess the coordination of eye and hand movements during both the generation of voluntary movements and during the expression of tics. Our experiments are designed to create situations in which participants must delay or inhibit a movement to an external sensory cue. We can measure the characteristics and frequency of motor tics elicited during the delay period. We can also compare directly eye-hand coordination in motor tics and in voluntary goal-directed movements. Recent research findings suggest that hand and eye movements may be subserved by parallel, but distinct, neural circuits. Moreover, these same circuits (involving the cerebral cortex and basal ganglia) are thought to be involved in TS. However, little is known about interactions between, and generalization of, tic behavior across these parallel circuits. A basic issue is whether TS represents a global impairment of all circuits, or whether it can selectively affect particular components of the system. For example, can tic behavior be observed in eye movements independent of hand movements? A second objective is to investigate the mechanism underlying tic generation. In particular, we will test whether tics reflect an inability to suppress prepared motor programs, or whether they are behaviors that are specifically generated in inappropriate situations. A third, more applied objective of this study is to develop quantitative tools and tasks to assess TS and treatment regimes. In the absence of well-controlled and properly measured tasks, important attributes of the disorder may be masked, and future treatments may be compromised. In summary, we propose to test three specific hypotheses: (1) Complex tics are purposeful, well-coordinated movements that exhibit the complete repertoire of characteristics observed with goal directed movements; (2) Tics reflect a failure to inhibit prepared motor responses; (3) Tics are not unique to a particular motor behavior, but generalize across different tasks. Douglas P. Munoz, Ph.D., J. Randall Flanagan, Ph.D. Queens University, Kingston, ON, Canada Award $36,490* *This study has been generously underwritten by Kasey, Nancy and Ronny Dubinsky and Barbara and Nat Dubinsky. Tourette Association of America Inc. – Research Grant Award 1999-2000