A Reinforcement-learning Account of Tourette Syndrome

2017 ◽  
Vol 41 (S1) ◽  
pp. S10-S10
Author(s):  
T. Maia
Keyword(s):  
Reinforcement Learning ◽  
Basal Ganglia ◽  
Tourette Syndrome ◽  
Behavioral Therapy ◽  
Mathematical Explanation ◽  
Reversal Training ◽  
Computational Theory ◽  
Habit Reversal Training ◽  
Habit Learning

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.

scholarly journals Shared mechanisms of auditory and non-auditory vocal learning in the songbird brain

2021 ◽  
Author(s):  
James McGregor ◽  
Abigail Grassler ◽  
Paul I. Jaffe ◽  
Amanda Louise Jacob ◽  
Michael Brainard ◽  
...  
Keyword(s):  
Reinforcement Learning ◽  
Basal Ganglia ◽  
General Principle ◽  
Auditory Feedback ◽  
Sensory Feedback ◽  
Vocal Learning ◽  
Neural Systems ◽  
Auditory Information ◽  
Vocal Plasticity

Songbirds and humans share the ability to adaptively modify their vocalizations based on sensory feedback. Prior studies have focused primarily on the role that auditory feedback plays in shaping vocal output throughout life. In contrast, it is unclear whether and how non-auditory information drives vocal plasticity. Here, we first used a reinforcement learning paradigm to establish that non-auditory feedback can drive vocal learning in adult songbirds. We then assessed the role of a songbird basal ganglia-thalamocortical pathway critical to auditory vocal learning in this novel form of vocal plasticity. We found that both this circuit and its dopaminergic inputs are necessary for non-auditory vocal learning, demonstrating that this pathway is not specialized exclusively for auditory-driven vocal learning. The ability of this circuit to use both auditory and non-auditory information to guide vocal learning may reflect a general principle for the neural systems that support vocal plasticity across species.

scholarly journals Effectiveness of behaviour therapy for children and adolescents with Tourette syndrome and chronic tic disorder in a real-world setting

2020 ◽  
Author(s):  
Per Andrén ◽  
Vera Wachtmeister ◽  
Julia Franzé ◽  
Caroline Speiner ◽  
Lorena Fernández de la Cruz ◽  
...  
Keyword(s):  
Young People ◽  
Tourette Syndrome ◽  
Real World ◽  
Post Treatment ◽  
Reversal Training ◽  
Behaviour Therapy ◽  
Tic Disorder ◽  
Chronic Tic Disorder ◽  
Habit Reversal Training ◽  
Tic Severity

Background: Treatment guidelines recommend behaviour therapy (BT) as the first-line intervention for patients with Tourette syndrome (TS) and chronic tic disorder (CTD). The efficacy of BT has been documented in randomised controlled trials (RCTs), but it is unclear to what extent these results are generalisable to real-world clinical settings, and whether the therapeutic gains are maintained long-term.Methods: In this naturalistic study, 74 young people with TS/CTD (aged 6 to 17) received BT (including psychoeducation, exposure with response prevention, habit reversal training or a combination of these treatments) at a specialist clinic in Stockholm, Sweden. Data were routinely collected at baseline, post-treatment, and at 3-, 6-, and 12-month follow-ups. Measures included the clinician-rated Yale Global Tic Severity Scale (YGTSS) and the Clinical Global Impression – Improvement scale (CGI-I), amongst others.Results: Tic severity and tic-related impairment (as measured by the YGTSS) improved significantly after treatment, with large within-group effect sizes (d=1.03 for the YGTSS Total Tic Severity Score, and d=1.37 for the YGTSS Impairment Score). At post-treatment, 57% of the participants were classified as treatment responders according to the CGI-I. Both tic severity and tic-related impairment continued to improve further through the follow-up, with 75% of the participants being rated as responders 12 months after the end of treatment. Significant improvements were also observed across a range of secondary measures.Conclusions: BT is an effective and durable treatment for young people with TS/CTD in a real-world clinical setting, with effects comparable to those reported in RCTs.

THE ROLE OF THE BASAL GANGLIA IN EXPLORATION IN A NEURAL MODEL BASED ON REINFORCEMENT LEARNING

2006 ◽  
Vol 16 (02) ◽  
pp. 111-124 ◽  
Author(s):  
D. SRIDHARAN ◽  
P. S. PRASHANTH ◽  
V. S. CHAKRAVARTHY
Keyword(s):  
Reinforcement Learning ◽  
Basal Ganglia ◽  
State Space ◽  
Chaotic Systems ◽  
Neural Model ◽  
Learning System ◽  
Substantia Nigra Pars Compacta ◽  
Water Pool ◽  
Oscillatory Dynamics

We present a computational model of basal ganglia as a key player in exploratory behavior. The model describes exploration of a virtual rat in a simulated water pool experiment. The virtual rat is trained using a reward-based or reinforcement learning paradigm which requires units with stochastic behavior for exploration of the system's state space. We model the Subthalamic Nucleus-Globus Pallidus externa (STN-GPe) segment of the basal ganglia as a pair of neuronal layers with oscillatory dynamics, exhibiting a variety of dynamic regimes such as chaos, traveling waves and clustering. Invoking the property of chaotic systems to explore state-space, we suggest that the complex exploratory dynamics of STN-GPe system in conjunction with dopamine-based reward signaling from the Substantia Nigra pars compacta (SNc) present the two key ingredients of a reinforcement learning system.

scholarly journals Contributions of the basal ganglia to action sequence learning and performance

2019 ◽  
Author(s):  
Eric Garr
Keyword(s):  
Reinforcement Learning ◽  
Basal Ganglia ◽  
Sequence Learning ◽  
Computational Framework ◽  
Action Sequence ◽  
Action Sequences ◽  
The Hierarchical Structure ◽  
And Performance ◽  
Action Sequencing

Animals engage in intricately woven and choreographed action sequences that are constructed from trial-and-error learning. The mechanisms by which the brain links together individual actions which are later recalled as fluid chains of behavior are not fully understood, but there is broad consensus that the basal ganglia play a crucial role in this process. This paper presents a comprehensive review of the role of the basal ganglia in action sequencing, with a focus on whether the computational framework of reinforcement learning can capture key behavioral features of sequencing and the neural mechanisms that underlie them. While a simple neurocomputational model of reinforcement learning can capture key features of action sequence learning, this model is not sufficient to capture goal-directed control of sequences or their hierarchical representation. The hierarchical structure of action sequences, in particular, poses a challenge for building better models of action sequencing, and it is in this regard that further investigations into basal ganglia information processing may be informative.

scholarly journals Trichotillomania: What Do We Know So Far?

2021 ◽  
pp. 1-7
Author(s):  
Daniel Fernandes Melo ◽  
Caren dos Santos Lima ◽  
Bianca Maria Piraccini ◽  
Antonella Tosti
Keyword(s):  
Selective Serotonin Reuptake Inhibitors ◽  
Behavioral Therapy ◽  
Treatment Plan ◽  
Interdisciplinary Approach ◽  
Comprehensive Treatment ◽  
Reversal Training ◽  
Pharmacological Management ◽  
Related Disorder ◽  
Pull Out ◽  
Habit Reversal Training

Trichotillomania is defined as an obsessive-compulsive or related disorder in which patients recurrently pull out hair from any region of their body. The disease affects mainly female patients, who often deny the habit, and it usually presents with a bizarre pattern nonscarring patchy alopecia with short hair and a negative pull test. Trichoscopy can reveal the abnormalities resulting from the stretching and fracture of hair shafts, and biopsy can be necessary if the patient or parents have difficulties in accepting the self-inflicted nature of a trichotillomania diagnosis. Trichotillomania requires a comprehensive treatment plan and interdisciplinary approach. Physicians should always have a nonjudgmental, empathic, and inviting attitude toward the patient. Behavioral therapy has been used with success in the treatment of trichotillomania, but not all patients are willing or able to comply with this treatment strategy. Pharmacotherapy can be necessary, especially in adolescents and adult patients. Options include tricyclic antidepressants, selective serotonin reuptake inhibitors, and glutamate-modulating agents. Glutamate-modulating agents such as N-acetylcysteine are a good first-line option due to significant benefits and low risk of side effects. Physicians must emphasize that the role of psychiatry-dermatology liaison is extremely necessary with concurrent support services for the patient and parents, in case of pediatric patients. In pediatric cases, parents should be advised and thoroughly educated that negative feedback and punishment for hair pulling are not going to produce positive results. Social support is a significant pillar to successful habit reversal training; therefore, physicians must convey the importance of familial support to achieving remission. This is a review article that aims to discuss the literature on trichotillomania, addressing etiology, historical aspects, clinical and trichoscopic features, main variants, differential diagnosis, diagnostic clues, and psychological and pharmacological management.

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