title: Habit learning in Tourette syndrome: a translational neuroscience approach to a developmental psychopathology.
abstract: BACKGROUND
  The etiology of Tourette syndrome (TS) involves disturbances in the structure and function of the basal ganglia. The basal ganglia mediate habit learning.
  
  
  OBJECTIVE
  To study habit learning in persons with TS.
  
  
  METHODS
  Patients with TS were compared with normal controls in performance on a probabilistic classification, or habit-learning task (weather prediction).
  
  
  METHODS
  University research institute.
  
  
  METHODS
  One hundred twenty-three children and adults, 56 with a diagnosis of TS and 67 healthy control subjects.
  
  
  METHODS
  Habit learning was assessed by the extent of improvement in accuracy of predictions and reaction times over trial blocks during performance of the weather prediction task. Declarative learning was assessed by performance on 3 tasks that required intact declarative memory functioning.
  
  
  RESULTS
  Children with TS were impaired at habit learning relative to normal controls (P = .01). This finding was replicated in the independent sample of adults with TS (P = .01). The rate of learning correlated inversely with the severity of tic symptoms across both samples (r = -0.34; P = .01). Thus, impaired learning accompanied more severe symptoms. Measures of declarative memory functioning, in contrast, were normal in the TS groups.
  
  
  CONCLUSIONS
  Striatal learning systems are uniquely dysfunctional in both children and adults with TS. The correlation of habit learning with symptom severity suggests that the number and severity of tics are a function of the degree to which the system for habit learning is dysfunctional. Thus, both the deficits in habit learning and the tic symptoms of TS are likely to be consequences of the previously reported anatomical and functional disturbances of the striatum in children and adults who have TS. The existence of a well-developed animal model for this learning system, which permits study of the neural and molecular bases of habit learning, has important implications for the neurobiological study of TS and for the development of new or improved therapeutics for this condition.
authors.affiliation: Division of Child and Adolescent Psychiatry in the Department of Psychiatry, New York State Psychiatric Institute and College of Physicians and Surgeons, Columbia University, New York 10032, USA. marshr@childpsych.columbia.edu
authors.forename: Rachel
authors.initials: R
authors.lastname: Marsh
authors.forename: Gerianne M
authors.initials: GM
authors.lastname: Alexander
authors.forename: Mark G
authors.initials: MG
authors.lastname: Packard
authors.forename: Hongtu
authors.initials: H
authors.lastname: Zhu
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Wingard
authors.forename: Georgette
authors.initials: G
authors.lastname: Quackenbush
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Peterson
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D001479:Basal Ganglia / Q000503:physiopathology*; D002648:Child; D015897:Comorbidity; D003463:Cues; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D010364:Pattern Recognition, Visual / Q000502:physiology; D011337:Probability Learning; D011930:Reaction Time / Q000502:physiology; D012720:Severity of Illness Index; D013647:Task Performance and Analysis; D005879:Tourette Syndrome / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D014887:Weather