A functional magnetic resonance imaging study of a large clinical cohort of children with Tourette syndrome.
ABSTRACT There is evidence that cortico-striato-thalamo-cortical pathways are involved in the pathophysiology of Tourette syndrome. During the performance of neuropsychological tests in subjects with Tourette syndrome there are suggestions for increased activity in the sensimotor cortex, supplementary motor areas, and frontal cortex. To replicate findings, the authors examined 22 medication-naive children with Tourette syndrome only, 17 medication-naive children with Tourette syndrome and comorbidity, and 39 healthy controls with functional magnetic resonance imaging (MRI). There were no differences in activation in brain regions between the children with Tourette syndrome (divided according to the presence of comorbidity) and healthy controls after correction for the confounders age, sex, and intelligence. Activation in the cingulated gyrus, temporal gyrus, and medial frontal gyrus was correlated significantly with obsessive-compulsive disorder score. The authors did not find significant correlations between activation patterns and age, sex, duration of disease, intelligence, severity of tics, and attention-deficit hyperactivity disorder (ADHD) score.
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ABSTRACT: Tourette syndrome is a neuropsychiatric disorder characterized by tics. Tic generation is often linked to dysfunction of inhibitory brain networks. Some previous behavioral studies found deficiencies in inhibitory motor control in Tourette syndrome, but others suggested normal or even better-than-normal performance. Furthermore, neural correlates of action inhibition in these patients are poorly understood. We performed event-related functional magnetic resonance imaging during a stop-signal reaction-time task in 14 uncomplicated adult Tourette patients and 15 healthy controls. In patients, we correlated activations in stop-signal reaction-time task with their individual motor tic frequency. Task performance was similar in both groups. Activation of dorsal premotor cortex was stronger in the StopSuccess than in the Go condition in healthy controls. This pattern was reversed in Tourette patients. A significant positive correlation was present between motor tic frequency and activations in the supplementary motor area during StopSuccess versus Go in patients. Inhibitory brain networks differ between healthy controls and Tourette patients. In the latter the supplementary motor area is probably a key relay of inhibitory processes mediating both suppression of tics and inhibition of voluntary action. © 2014 International Parkinson and Movement Disorder SocietyMovement Disorders 07/2014; 29(12). · 5.63 Impact Factor
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ABSTRACT: Tic disorders are childhood onset neuropsychiatric disorders characterized by motor and/or vocal tics. Research has demonstrated that children with chronic tics (including Tourette syndrome and Chronic Tic Disorder: TS/CTD) can suppress tics, particularly when an immediate, contingent reward is given for successful tic suppression. As a diagnosis of TS/CTD requires tics to be present for at least one year, children in these tic suppression studies had been living with tics for quite some time. Thus, it is unclear whether the ability to inhibit tics is learned over time or present at tic onset. Resolving that issue would inform theories of how tics develop and how behavior therapy for tics works. We investigated tic suppression in school-age children as close to the time of tic onset as possible, and no later than six months after onset. Children were asked to suppress their tics both in the presence and absence of a contingent reward. Results demonstrated that these children, like children with TS/CTD, have some capacity to suppress tics, and that immediate reward enhances that capacity. These findings demonstrate that the modulating effect of reward on inhibitory control of tics is present within months of tic onset, before tics have become chronicDevelopmental Cognitive Neuroscience 08/2014; 11. · 3.71 Impact Factor
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ABSTRACT: The cortical dynamics of somatosensory processing can be investigated using vibrotactile psychophysics. It has been suggested that different vibrotactile paradigms target different cortical mechanisms, and a number of recent studies have established links between somatosensory cortical function and measurable aspects of behaviour. The relationship between cortical mechanisms and sensory function is particularly relevant with respect to developmental disorders in which altered inhibitory processing are postulated such as ASD and ADHD. In this study, a vibrotactile battery consisting of nine tasks (incorporating reaction time, detection threshold, amplitude- and frequency discrimination) is applied to a cohort of healthy adults and a cohort of typically developing children to assess the feasibility of such a vibrotactile battery in both cohorts, and compare performance between children and adults. The results show that children and adults are both able to perform these tasks with similar performance, although children are slightly less sensitive in frequency discrimination. Performance within different task-groups clusters together in adults, providing further evidence that these tasks tap into different cortical mechanisms, which is discussed. This clustering is not shown in children, possibly indicative of development and larger variability. In conclusion, in this study we show that both children and adults are able to perform an extensive vibrotactile battery and we show feasibility of applying this battery for application to other (e.g. neurodevelopmental) cohorts to probe different cortical mechanisms.Journal of neuroscience methods 05/2013; · 2.30 Impact Factor