A Critical Review of Habit Learning and the Basal Ganglia

BackgroundTourette syndrome (TS) has long been thought to involve dopaminergic disturbances, given the effectiveness of antipsychotics in diminishing tics. Molecular-imaging studies have, by and large, confirmed that there are specific alterations in the dopaminergic system in TS. In parallel, multiple lines of evidence have implicated the motor cortico-basal ganglia-thalamo-cortical (CBGTC) loop in TS. Finally, several studies demonstrate that patients with TS exhibit exaggerated habit learning. This talk will present a computational theory of TS that ties together these multiple findings.MethodsThe computational theory builds on computational reinforcement-learning models, and more specifically on a recent model of the role of the direct and indirect basal-ganglia pathways in learning from positive and negative outcomes, respectively.ResultsA model defined by a small set of equations that characterize the role of dopamine in modulating learning and excitability in the direct and indirect pathways explains, in an integrated way: (1) the role of dopamine in the development of tics; (2) the relation between dopaminergic disturbances, involvement of the motor CBGTC loop, and excessive habit learning in TS; (3) the mechanism of action of antipsychotics in TS; and (4) the psychological and neural mechanisms of action of habit-reversal training, the main behavioral therapy for TS.ConclusionsA simple computational model, thoroughly grounded on computational theory and basic-science findings concerning dopamine and the basal ganglia, provides an integrated, rigorous mathematical explanation for a broad range of empirical findings in TS.Disclosure of interestThe author has not supplied his declaration of competing interest.

Download Full-text

Review for "Habit learning in hierarchical cortex - basal ganglia loops"

10.1111/ejn.14730/v1/review1 ◽

2020 ◽

Author(s):

Jon Horvitz

Keyword(s):

Basal Ganglia ◽

Habit Learning

Download Full-text

Dissociation of Habit-Learning in Parkinson's and Cerebellar Disease

Journal of Cognitive Neuroscience ◽

10.1162/089892902317362001 ◽

2002 ◽

Vol 14 (3) ◽

pp. 493-499 ◽

Cited By ~ 48

Author(s):

K. Witt ◽

A. Nuhsman ◽

G. Deuschl

Keyword(s):

Basal Ganglia ◽

Implicit Learning ◽

Explicit Memory ◽

Learning Task ◽

Motor Deficits ◽

Temporal Region ◽

Cerebellar Disease ◽

Probabilistic Classification ◽

Habit Learning ◽

Improved Performance

Damage to the medial-temporal region is known to result in declarative (explicit) memory deficits but nondeclarative (implicit) memory is largely unaffected by such lesions. Earlier studies have shown that some forms of implicit learning depend on cerebellar circuits but remain preserved following affections of the basal ganglia circuits. It is unknown which forms of implicit learning persist in patients with cerebellar pathology but are affected after basal ganglia lesions. Therefore, we determined if a test sensitive for habit-learning (probabilistic classification task) resulted in normal values for patients with cerebellar disease but resulted in affected results in patients with Parkinson's disease (PD). To this end, 23 patients with PD, 16 patients with familial or idiopathic cerebellar degeneration (CD), and 20 controls were tested for habit-learning. There was no impairment of patients with CD for the early learning period but there was abnormal learning in the PD group. For a later learning period, the patients with the PD showed improved performance. We conclude that the probabilistic learning task is an implicit, nonmotor learning task which is sensitive for basal ganglia pathology but remains unaffected in the case of cerebellar pathology. Such a test may be of special interest for the detection and possible neurobehavioral treatment of cognitive and motor deficits.

Download Full-text