Neural, physiological and behavioural correlates of empathy for pain in Tourette syndrome.

Persons with Tourette syndrome show altered social behaviours, such as echophenomena and increased personal distress in emotional situations. These symptoms may reflect an overactive mirror neuron system, causing both increased automatic imitation and a stronger tendency to share others' emotions. To test this, we measured the individual level of echophenomena with a video protocol and experimentally induced empathy for pain in 21 participants with Tourette syndrome and 25 matched controls. In the empathy for pain paradigm, pictures of hands and feet in painful or neutral situations were presented, while we measured participants' EEG and skin conductance response. Changes in somatosensory mu suppression during the observation of the pictures and pain ratings were compared between groups, and correlations were calculated with the occurrence of echophenomena, self-reported empathy and clinical measures. Our Tourette syndrome sample showed significantly more echophenomena than controls, but the groups showed no behavioural differences in empathic abilities. However, controls, but not patients with Tourette syndrome, showed the predicted increased mu suppression when watching painful compared to neutral actions. While echophenomena were present in all persons with Tourette syndrome, the hypothesis of an overactive mirror neuron system in Tourette syndrome could not be substantiated. On the contrary, the Tourette syndrome group showed a noticeable lack of mu attenuation in response to pain stimuli. In conclusion, we found a first hint of altered processing of others' emotional states in a brain region associated with the mirror neuron system.

Cognitive Tic-Like Phenomena in Gilles de la Tourette Syndrome.

Coprolalia and echophenomena repeated in the patients' mind (CTPh-cognitive tic-like phenomena) have been rarely recognized as part of Gilles de la Tourette syndrome (GTS) symptomatology and their assignment to tics, OCD or other psychopathologies has not been settled. The aim of the paper was to assess the incidence and clinical associations of CTPh in GTS, and to establish if CTPh belong to the tic spectrum. We performed a prospective, one-registration study on a cohort of 227 consecutive patients with GTS. CTPh were diagnosed during the interview and defined as brief, sudden, involuntary thoughts that had corresponding complex vocal tics. CTPh occurred at some point in the lives of 34 (15.0%) patients. The median age at onset of CTPh was 14.5 years (IQR: 10.5-17.5). CTPh were found more frequently in adults, with the most frequent onset in adolescence (44.1%). Four mental phenomena resembling tics were recognized: echolalia (n = 17), coprolalia (n = 16), palilalia (n = 13) and repeating of words in the mind (n = 7). The older the age of patients, the more severe tics, and anxiety disorder significantly correlated with CTPh. CTPh may be considered as a part of tic spectrum with a substantial impact of anxiety disorder. CTPh are a late and age-related symptom of GTS.

Automatic imitation in youngsters with Gilles de la Tourette syndrome: A behavioral study.

It is widely known that humans have a tendency to imitate each other and that appropriate modulation of automatic imitative behaviors has a crucial function in social interactions. Gilles de la Tourette syndrome (GTS) is a childhood-onset neuropsychiatric disorder characterized by motor and phonic tics. Apart from tics, patients with GTS are often reported to show an abnormal tendency to automatically imitate others' behaviors (i.e., echophenomena), which may be related to a failure in top-down inhibition of imitative response tendencies. The aim of the current study is to explore the top-down inhibitory mechanisms on automatic imitative behaviors in youngsters with GTS. Error rates and reaction times from 32 participants with GTS and 32 controls were collected in response to an automatic imitation task assessing the influence of observed movements displayed in the first-person perspective on congruent and incongruent motor responses. Results showed that participants with GTS had higher error rates than controls, and their responses were faster than those of controls in incompatible stimuli. Our findings provide novel evidence of a key difference between youngsters with GTS and typically developing participants in the ability to effectively control the production of own motor responses to sensory inputs deriving from observed actions.

A Neural Basis for Contagious Yawning.

Contagious yawning, in which yawning is triggered involuntarily when we observe another person yawn, is a common form of echophenomena-the automatic imitation of another's words (echolalia) or actions (echopraxia) [1]. The neural basis for echophenomena is unknown; however, it has been proposed that it is linked to disinhibition of the human mirror-neuron system [1-4] and hyper-excitability of cortical motor areas [1]. We investigated the neural basis for contagious yawning using transcranial magnetic stimulation (TMS). Thirty-six adults viewed video clips that showed another individual yawning and, in separate blocks, were instructed to either resist yawning or allow themselves to yawn. Participants were videoed throughout and their yawns or stifled yawns were counted. We used TMS to quantify motor cortical excitability and physiological inhibition for each participant, and these measures were then used to predict the propensity for contagious yawning across participants. We demonstrate that instructions to resist yawning increase the urge to yawn and alter how yawns are expressed (i.e., full versus stifled yawns) but do not alter the individual propensity for contagious yawning. By contrast, TMS measures of cortical excitability and physiological inhibition were significant predictors of contagious yawning and accounted for approximately 50% of the variability in contagious yawning. These data demonstrate that individual variability in the propensity for contagious yawning is determined by cortical excitability and physiological inhibition in the primary motor cortex.

An introduction to the clinical phenomenology of Tourette syndrome.

Tourette syndrome (TS) is the primary tic disorder that reaches most commonly medical attention and monitoring, with an estimated prevalence close to 1% between 5 and 18 years of age. Motor and phonic tics are the core features of TS. In addition to their well-characterized phenomenology, tics display a peculiar variability over time, which is strongly influenced by a variety of contextual factors. The sensory phenomena of TS are increasingly recognized as another crucial symptom of TS and consist of premonitory urges and somatic hypersensitivity. A relevant proportion of patients with TS display complex, tic-like, repetitive behaviors that include echophenomena, coprophenomena, and nonobscene socially inappropriate behaviors (NOSIBs). The burden of behavioral comorbidities is very important in determining the degree of disability of TS patients. Only a small minority of TS patients presents exclusively with a tic disorder. Obsessive-compulsive symptoms and related disorder (OCD) are common in TS, and the clinical distinction between compulsions and complex tics may be difficult in some cases. Probably, the presence of comorbid attention deficit hyperactivity disorder (ADHD) is the main determinant of cognitive dysfunction in TS patients and influences heavily also the risk of developing disruptive behaviors. Affective disorders, impulse control disorders, autism spectrum disorders, and personality disorders complete the wide psychopathological spectrum of this condition, but have been less investigated than OCD and ADHD. The complexity of the Tourette spectrum has been confirmed by cluster and factor analytical approaches, and is likely to inform the study of the genetic basis of this disorder, as well as future reappraisal of its nosography, with the development of novel clinical subtypes.