Enhanced habit formation in Gilles de la Tourette syndrome

Abstract

Tics are sometimes described as voluntary movements performed in an automatic or habitual way. Here, we addressed the question of balance between goal-directed and habitual behavioural control in Gilles de la Tourette syndrome and formally tested the hypothesis of enhanced habit formation in these patients. To this aim, we administered a three-stage instrumental learning paradigm to 17 unmedicated and 17 antipsychotic-medicated patients with Gilles de la Tourette syndrome and matched controls. In the first stage of the task, participants learned stimulus-response-outcome associations. The subsequent outcome devaluation and 'slip-of-action' tests allowed evaluation of the participants' capacity to flexibly adjust their behaviour to changes in action outcome value. In this task, unmedicated patients relied predominantly on habitual, outcome-insensitive behavioural control. Moreover, in these patients, the engagement in habitual responses correlated with more severe tics. Medicated patients performed at an intermediate level between unmedicated patients and controls. Using diffusion tensor imaging on a subset of patients, we also addressed whether the engagement in habitual responding was related to structural connectivity within cortico-striatal networks. We showed that engagement in habitual behaviour in patients with Gilles de la Tourette syndrome correlated with greater structural connectivity within the right motor cortico-striatal network. In unmedicated patients, stronger structural connectivity of the supplementary motor cortex with the sensorimotor putamen predicted more severe tics. Overall, our results indicate enhanced habit formation in unmedicated patients with Gilles de la Tourette syndrome. Aberrant reinforcement signals to the sensorimotor striatum may be fundamental for the formation of stimulus-response associations and may contribute to the habitual behaviour and tics of this syndrome.

Anomalous Putamen Volume in Children With Complex Motor Stereotypies

“…Participants were excluded if there was a history of motor/vocal tics; but not excluded if they had co-occurring Attention-deficit/Hyperactivity Disorder (ADHD) or Obsessive Compulsive Disorder. The rationale for excluding individuals with tic disorders was twofold: 1) both disorders are proposed to involve habitual pathways 6, 7 , and, 2) prior reports in Tourette syndrome suggest alterations involving both the putamen and caudate nucleus. For example, volumetric MRI studies in individuals with Tourette syndrome have shown smaller caudate volumes bilaterally (which did not correlate with symptom severity) and variable changes in the putamen (reduced, larger, or changes in symmetry) 8 .…”

An investigation of habit learning in Anorexia Nervosa

“…A shift in balance away from goal-directed control and towards excessive habit learning has been shown in substance dependence (Sjoerds et al, 2013; Voon et al, 2014), OCD (Gillan et al, 2015; Gillan et al, 2013; Gillan et al, 2011; Voon et al, 2014), binge eating disorder (BED) (Voon et al, 2014), and Tourette’s syndrome (Delorme et al, 2015). Walsh (2013) outlines the mechanisms by which aberrant habit formation may contribute to the maintenance of dietary restriction in AN.…”

General Habit Propensity Relates to the Sensation Seeking Subdomain of Impulsivity But Not Obesity

“…Individual differences in action control were measured using an established instrumental learning task (de Wit et al, 2007, 2012b; Gillan et al, 2011; Worbe et al, 2015; Delorme et al, 2016). In this task, participants were trained to perform specific responses which were indicated by certain associated stimuli, to obtain rewarding outcomes.…”

“…In the critical ‘slips-of-action’ test phase, some of the outcomes were devalued, allowing evaluation of participants’ ability to adapt responding based on the current goal or outcome value, as opposed to relying on inflexible stimulus-response habits. We restricted the experimental procedure to the standard discrimination type of the original ‘slips-of-action’ test phase, as this discrimination type has been shown to be sufficiently sensitive to evaluate the balance between habitual and goal-directed action control in clinical and pre-clinical pathological conditions (Gillan et al, 2011; Delorme et al, 2016; Snorrason et al, 2016) and after pharmacological manipulations affecting dopamine and serotonin neurotransmission (de Wit et al, 2012a; Delorme et al, 2016). …”