Voluntary inhibitory motor control over involuntary tic movements

Abstract

Inhibitory control is crucial for normal adaptive motor behavior. In hyperkinesias, such as tics, disinhibition within the cortico-striato-thalamo-cortical loops is thought to underlie the presence of involuntary movements. Paradoxically, tics are also subject to voluntary inhibitory control. This puzzling clinical observation questions the traditional definition of tics as purely involuntary motor behaviors. Importantly, it suggests novel insights into tic pathophysiology. In this review, we first define voluntary inhibitory tic control and compare it with other notions of tic control from the literature. We then examine the association between voluntary inhibitory tic control with premonitory urges and review evidence linking voluntary tic inhibition to other forms of executive control of action. We discuss the somatotopic selectivity and the neural correlates of voluntary inhibitory tic control. Finally, we provide a scientific framework with regard to the clinical relevance of the study of voluntary inhibitory tic control within the context of the neurodevelopmental disorder of Tourette syndrome. We identify current knowledge gaps that deserve attention in future research. © 2018 International Parkinson and Movement Disorder Society.

The interindividual variability of transcranial magnetic stimulation effects: Implications for diagnostic use in movement disorders

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“…Tics such as those encountered in Tourette syndrome (TS) are movements or sounds that resemble voluntary actions, but are repetitive, often exaggerated, and not contextually appropriate . Tics are often preceded by sensory phenomena termed “premonitory urges” and can be voluntarily suppressed . The interaction between involuntary tic movements and the capacity to exert volitional inhibitory tic control remains controversial …”

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