Inhibitory Control and Tic Generation

Abstract

Abstract Tic disorders are characterized by a surplus of brief movements and sounds that share some of the characteristics of voluntary actions but occur repetitively and are inapposite to discernable context. Tics are most commonly observed in primary tic disorders, and are often accompanied by additional neuropsychiatric features, including impulsive and socially disruptive behaviors. This lends support to the hypothesis of a core inhibitory deficit at different organization levels of brain structure and function. This chapter dissects evidence supporting the disinhibition model, starting from neuronal composition aberrations within the cortico-basal-ganglia-thalamo-cortical loops to their putative consequences in behavioral output. Specifically, it provides an overview of the neuropathological and functional neuroanatomic changes of different cell populations within the basal ganglia, with a focus in GABA-ergic and cholinergic interneurons, dopaminergic neurotransmission, and the glutamate–glutamine-GABA cycle. Evidence from animal models of tic disorders, alongside studies of cortical neurophysiology are also discussed. Finally, an account of behavioral studies related both to control of voluntary actions and tics is provided, and knowledge gaps are listed to motivate future studies in the field.