Motor excitability is reduced prior to voluntary movements in children and adolescents with Tourette syndrome

Tourette syndrome (TS) is a neuro‐developmental disorder characterized by the occurrence of motor and vocal tics: involuntary, repetitive, stereotyped behaviours that occur with a limited duration, often typically many times in a single day. Previous studies suggest that children and adolescents with TS may undergo compensatory, neuroplastic changes in brain structure and function that help them gain control over their tics. In the current study we used single‐pulse and dual‐site paired‐pulse transcranial magnetic stimulation (TMS), in conjunction with a manual choice reaction time task that induces high levels of inter‐manual conflict, to investigate this conjecture in a group of children and adolescents with TS, but without co‐morbid Attention Deficit Hyperactivity Disorder (ADHD). We found that performance on the behavioural response‐conflict task did not differ between the adolescents with TS and a group of age‐matched typically developing individuals. By contrast, our study demonstrated that cortical excitability, as measured by TMS‐induced motor‐evoked potentials (MEPs), was significantly reduced in the TS group in the period immediately preceding a finger movement. This effect is interpreted as consistent with previous suggestions that the cortical hyper‐excitability that may give rise to tics in TS is actively suppressed by cognitive control mechanisms. Finally, we found no reliable evidence for altered patterns of functional inter‐hemispheric connectivity in TS. These results provide evidence for compensatory brain reorganization that may underlie the increased self‐regulation mechanisms that have been hypothesized to bring about the control of tics during adolescence.     

Thermal sensitivity in Tourette syndrome: preliminary report

The effects of heat on tic symptoms were studied in a sample of 78 adults with Tourette syndrome. 62 men and 16 women completed a survey concerning the type, onset, and course of their tics. 10 adult male subjects also participated in a thermal challenge during which ambient temperature was raised from 22 degrees C to 35 degrees C following a control period. Of the 78, 24% or 19 reported increased tics upon exposure to heat. Compared to the remaining 59 subjects, there were no differences in sex distribution, current age, or overall course of illness. In the thermal challenge, there was general increase in tics that was correlated with sweat rate (r = .55, p = .001). This effect was prominent in 5 of 10 subjects (rs = .29 to .63). There were no mean differences in current age, age of onset, or current severity of symptoms between the five subjects of each group. Tic symptoms in a subgroup of patients with Tourette syndrome may be sensitive to heat. Abnormal heat regulation is not a likely explanation for the observed increase in tics. The increase may be due to normal heat-loss mechanisms through dopaminergic pathways.     

Motor excitability during movement preparation in Tourette syndrome

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the occurrence of motor and vocal tics. TS has been linked to the impaired operation of cortical‐striatal‐thalamic‐cortical circuits that give rise to hyper‐excitability of cortical motor areas, which may be exacerbated by dysfunctional intra‐cortical inhibitory mechanisms. That said, many individuals gain control over their tics during adolescence and it has been suggested that this increased control arises as a result of the development of mechanisms that operate to suppress corticospinal excitability (CSE) ahead of volitional movements. Here we used single‐pulse transcranial magnetic stimulation (TMS) in conjunction with a manual Go/NoGo task to investigate alterations in CSE ahead of volitional movements in a group of adolescents with TS (N = 10). Our study demonstrated that CSE, as measured by TMS‐induced motor‐evoked potentials (MEPs), was significantly reduced in the TS group in the period immediately preceding a finger movement. More specifically, we show that individuals with TS, unlike their age‐matched controls, do not exhibit the predicted increase in mean MEP amplitude and decrease in MEP variability that immediately precede the execution of volitional movements in typically developing young adults. Finally, we report that the magnitude of the rise in MEP amplitude across the movement preparation period in TS is significantly negatively correlated with clinical measures of motor tic severity, suggesting that individuals with severe motor tics are least able to modulate motor cortical excitability.     

Premonitory urges are associated with decreased grey matter thickness within the insula and sensorimotor cortex in young people with Tourette syndrome

Tourette syndrome (TS) is a neurological disorder characterized by vocal and motor tics and is associated with cortical–striatal–thalamic–cortical circuit (CSTC) dysfunction and hyperexcitability of cortical limbic and motor regions, which are thought to lead to the occurrence of tics. Importantly, individuals with TS often report that their tics are preceded by ‘premonitory sensory phenomena’ (PSP) that are described as uncomfortable cognitive or bodily sensations that precede the execution of a tic, and are experienced as a strong urge for motor discharge. While the precise role played by PSP in the occurrence of tics is controversial, PSP are nonetheless of considerable theoretical and clinical importance in TS, not least because they form the core component in many of the behavioural therapies that are currently used in the treatment of tic disorders. In this study, we investigated the brain structure correlates of PSP. Specifically, we conducted a whole‐brain analysis of cortical (grey matter) thickness in 29 children and young adults with TS and investigated the association between grey matter thickness and PSP. We demonstrate for the first time that PSP are inversely associated with grey matter thickness measurements within the insula and sensorimotor cortex. We also demonstrate that grey matter thickness is significantly reduced in these areas in individuals with TS relative to a closely age‐ and gender‐matched group of typically developing individuals and that PSP ratings are significantly correlated with tic severity.     

Treatment of vocal tics in children with Tourette syndrome: investigating the efficacy of habit reversal

Habit reversal was used to treat vocal tics in 5 children with Tourette syndrome. Vocal tics were reduced in 4 of the 5 children, the untreated motor tics did not increase, and treatment was acceptable to the children's parents.     

Ambulatory accelerometry to quantify involuntary movements and tics in the syndrome of Gilles de la Tourette

Gilles de la Tourette syndrome is a chronic neuropsychiatric disorder characterizedby recurrent and involuntary tics, in addition to complex behavioral symptoms. Objective quantification of the nonspecific movements in Tourette patients can contribute much to understanding the pathophysiology of this disease. We used three accelerometersto characterizehead movement patterns and to objectively quantify head motility in the lateral, sagittal, and transversal planes in 9 Tourette patients and 14 controls during periods of rest, conversation, and watching a videotape with an entertaining program. Characteristic head movement patterns can be documented by means of accelerometry. Head motility levels in the lateral, sagittal, and transversal planes were significantly higher in the patients than in the controls during all the procedures. The patients and the controls showed a similar significant increase in head motility during conversation, but not during video watching. This first study shows that for both standardized and ambulatory research, accelerometry may provide an objective tool by which to quantify the severity and temporal dynamics of tics or nonspecific movements.     

Executive and Attention Functioning Among Children in the PANDAS Subgroup

Evidence from past studies indicates that adults and children with Obsessive-Compulsive Disorder (OCD) and Tourette syndrome (TS) experience subtle neuropsychological deficits. Less is known about neuropsychological functioning of children and adolescents with a symptom course consistent with the PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infection) subgroup of OCD and tics. To provide such information, we administered three tests of attention control and two of executive function to 67 children and adolescents (ages 5–16) diagnosed with OCD and/or tics and a symptom course consistent with the PANDAS subgroup and 98 healthy volunteers (HV) matched by age, sex, and IQ. In a paired comparison of the two groups, the PANDAS subjects were less accurate than HV in a test of response suppression. Further, in a two-step linear regression analysis of the PANDAS group in which clinical variables were added stepwise into the model and in the second step matching variables (age, sex, and IQ) were added, IQ emerged as a predictor of performance on this task. In the same analysis, ADHD diagnosis and age emerged as predictors of response time in a continuous performance task. Subdividing the PANDAS group by primary psychiatric diagnosis revealed that subjects with TS or OCD with tics exhibited a longer response time compared to controls than subjects with OCD only, replicating previous findings within TS and OCD. This study demonstrates that children with PANDAS exhibit neuropsychological profiles similar to those of their primary psychiatric diagnosis.     

Ambiguous Figures and the Content of Experience

Representationalism is the position that the phenomenal character of an experience is either identical with, or supervenes on, the content of that experience. Many representationalists hold that the relevant content of experience is nonconceptual. I propose a counter‐example to this form of representationalism that arises from the phenomenon of Gestalt switching, which occurs when viewing ambiguous figures. First, I argue that one does not need to appeal to the conceptual content of experience or to judgements to account for Gestalt switching. I then argue that experiences of certain ambiguous figures are problematic because they have different phenomenal characters but that no difference in the nonconceptual content of these experiences can be identified. I consider three solutions to this problem that have been proposed by both philosophers and psychologists and conclude that none can account for all the ambiguous figures that pose the problem. I conclude that the onus is on representationalists to specify the relevant difference in content or to abandon their position.     

Examining the neural antecedents of tics in Tourette syndrome using electroencephalography

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the occurrence of motor and vocal tics. TS is associated with cortical–striatal–thalamic–cortical circuit dysfunction and hyper-excitability of cortical limbic and motor regions that lead to the occurrence of tics. Importantly, individuals with TS often report that their tics are preceded by premonitory sensory/urge phenomena (PU) that are described as uncomfortable bodily sensations that precede the execution of a tic and are experienced as an urge for motor discharge. While tics are most often referred to as involuntary movements, it has been argued by some that tics should be viewed as voluntary movements that are executed in response to the presence of PU. To investigate this issue further, we conducted a study using electroencephalography (EEG). We recorded movement-related EEG (mu- and beta-band oscillations) during (1) the immediate period leading up to the execution of voluntary movements by a group of individuals with TS and a group of matched healthy control participants, and (2) the immediate period leading up to the execution of a tic in a group of individuals with TS. We demonstrate that movement-related mu and beta oscillations are not reliably observed prior to tics in individuals with TS. We interpret this effect as reflecting the greater involvement of a network of brain areas, including the insular and cingulate cortices, the basal ganglia and the cerebellum, in the generation of tics in TS. We also show that beta-band desynchronization does occur when individuals with TS initiate voluntary movements, but, in contrast to healthy controls, desynchronization of mu-band oscillations is not observed during the execution of voluntary movements for individuals with TS. We interpret this finding as reflecting a dysfunction of physiological inhibition in TS, thereby contributing to an impaired ability to suppress neuronal populations that may compete with movement preparation processes.     

Minima sensibilia: Against the dynamic snapshot model of temporal experience

In our wakeful conscious lives, the experience of time and dynamic temporal phenomena—such as continuous motion and change—appears to be ubiquitous. How is it that temporality is woven into our conscious experience? Is it through perceptual experience presenting a series of instantaneous states of the world, which combine together—in a sense which would need to be specified—to give us experience of dynamic temporal phenomena? In this paper, I argue that this is not the case. Several authors have recently proposed dynamic snapshot models of temporal experience—such as Prosser and Arstila, building upon Le Poidevin—according to which, perceptual experience has no temporal content of a non‐zero extent. I argue that there is an absence of motivation for such a view; I develop and defend the claim that perceptual experience minimally presents something of some non‐zero temporal extent as such.     

Cerebellar neurophysiology in Gilles de la Tourette syndrome and its role as a target for therapeutic intervention

Therapy resistance of approximately one‐third of patients with Gilles de la Tourette syndrome (GTS) requires consideration of alternative therapeutic interventions. The article demonstrates the role of the cerebellum in neuropsychiatric disorders and GTS in particular, specifically its role in functions relating to motor and cognitive symptoms. Certain circuits in the cerebellum have been shown to undergo learning‐induced changes during conditioning, with cells in the cortex of the cerebellum appearing to decrease their activity whilst those in deep nuclei seem to do the inverse. Evidence exists showing that abnormal excitability of the motor cortex via the cerebellum could be expected to participate in motor tics in GTS possibly due to aberrations in certain structures of involved circuits. The role of the cerebellum in learning and plasticity processes renders it a strategic and valuable structure to consider for brain stimulation when investigating potential treatment options for neuropsychiatric disorders such as GTS. This article puts forth the concept of using non‐invasive and invasive brain stimulation techniques as a novel platform for non‐pharmacological neuromodulation of GTS symptoms.     

Phenomenology of Bodily Integrity in Disfiguring Breast Cancer

In this paper, I explore the meaning of bodily integrity in disfiguring breast cancer. Bodily integrity is a normative principle precisely because it does not simply refer to actual physical or functional intactness. It rather indicates what should be regarded and respected as inviolable in vulnerable and damageable bodies. I will argue that this normative inviolability or wholeness can be based upon a person's embodied experience of wholeness. This phenomenological stance differs from the liberal view that identifies respect for integrity with respect for autonomy (resulting in an invalidation of bodily integrity's proper normative meaning), as well as from the view that bodily integrity is based upon ideologies of wholeness (which runs the risk of being disadvantageous to women). I propose that bodily integrity involves a process of identification between the experience of one's body as “Leib” and the experience of one's body as “Körper.” If identification fails or is not possible, one's integrity is threatened. This idea of bodily integrity can support breast cancer patients and survivors in making decisions about possible corrective interventions. To implement this idea in oncology care, empirical‐phenomenological research needs to establish how breast cancer patients express their embodied self‐experiences.     

The role of the cingulate cortex in the generation of motor tics and the experience of the premonitory urge-to-tic in Tourette syndrome

Tourette syndrome (TS) is a neurological disorder of childhood onset that is characterized by the occurrence of motor and vocal tics. TS is associated with cortical-striatal-thalamic-cortical circuit [CSTC] dysfunction and hyper-excitability of cortical limbic and motor regions that are thought to lead to the occurrence of tics. Individuals with TS often report that their tics are preceded by ‘premonitory sensory/urge phenomena’ (PU) that are described as uncomfortable bodily sensations that precede the execution of a tic and are experienced as a strong urge for motor discharge. While the precise role played by PU in the occurrence of tics is largely unknown, they are nonetheless of considerable theoretical and clinical importance as they form a core component of many behavioural therapies used in the treatment of tic disorders. Recent evidence indicates that the cingulate cortex may play an important role in the generation of PU in TS, and in ‘urges-for-action’ more generally. In the current study, we utilized voxel-based morphometry (VBM) techniques, together with ‘seed-to-voxel’ structural covariance network (SCN) mapping, to investigate the putative role played by the cingulate cortex in the generation of motor tics and the experience of PU in a relatively large group of young people with TS. Whole-brain VBM analysis revealed that TS was associated with clusters of significantly reduced grey matter volumes bilaterally within: the orbito-frontal cortex; the cerebellum; and the anterior and mid-cingulate cortex. Similarly, analysis of SCNs associated with bilateral mid- and anterior cingulate ‘seed’ regions demonstrated that TS is associated with increased structural covariance primarily with the bilateral motor cerebellum; the inferior frontal cortex; and the posterior cingulate cortex.     

How the World Is Measured Up in Size Experience

I develop a Russellian representationalist account of size experience that draws importantly from contemporary vision science research on size perception. The core view is that size is experienced in ‘body‐scaled’ units. So, an object might, say, be experienced as two eye‐level units high. The view is sharpened in response to Thompson’s (forthcoming) Doubled Earth example. This example is presented by Thompson as part of an argument for a Fregean view of size experience. But I argue that the Russellian view I develop handles the Doubled Earth example in a natural and illuminating way, thereby avoiding the need to posit irreducible experiential ‘modes of presentation’. I also address a kind of neo‐Fregean ‘reference‐fixing’ view of size experience, that shares features with the Russellian view developed. I give reasons for favoring the latter. Finally, I argue that Peacocke’s claim that spatial experience is ‘unit free’ is not persuasive.     

Identification,Meaning, and the Normativity of Social Roles

Abstract: We are all familiar with the way in which social roles, such as mother, father, professor, club football coach, citizen, and so on, confront us with clusters of duties that purport to bind us. Though we generally experience these role‐duties as normatively binding, we might question this. What reason do role‐occupants have for conforming to the duties that define their roles? I argue that the agent who identifies with her role thereby has a weighty and important justificatory reason for conforming to the role's defining duties: namely, the identifying agent realizes the fundamental goods of meaning and self‐determination by doing so. This is an important normative ground of role‐duties because it, unlike the grounds of natural duty or voluntary assumption, ensures that the duties it grounds are not alien impositions but rather are elements of the identifying agent's wellbeing. I also argue that role‐identification provides a reason that shares many of the characteristics of a moral reason, and I argue that role‐identification in tandem with the principle of fair play grounds a moral duty to conform to one's role‐duties.     

Enhanced saccadic control in young people with Tourette syndrome despite slowed pro‐saccades

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by motor and vocal tics. Tics are repetitive and uncontrolled behaviours that have been associated with basal ganglia dysfunction. We investigated saccadic eye movements in a group of young people with TS but without co‐morbid ADHD. Participants performed two tasks. One required them to perform only pro‐saccade responses (pure pro‐saccade task). The other involved shifting, unpredictably, between executing pro‐ and anti‐saccades (mixed saccade task). We show that in the mixing saccade task, the TS group makes significantly fewer errors than an age‐matched control group, while responding equally fast. By contrast, on the pure pro‐saccade task, the TS group were shown to be significantly slower to initiate and to complete the saccades (longer movement duration and decreased peak velocity) than controls, while movement amplitude and direction accuracy were not different. These findings demonstrate enhanced shifting ability despite slower reflexive responding in TS and are discussed with respect to a disorder‐related adaptation for increased cognitive regulation of behaviour.     

Perceptual Content Defended

Recently, the thesis that experience is fundamentally a matter of representing the world as being a certain way has been questioned by austere relationalists. I defend this thesis by developing a view of perceptual content that avoids their objections. I will argue that on a relational understanding of perceptual content, the fundamental insights of austere relationalism do not compete with perceptual experience being representational. As it will show that most objections to the thesis that experience has content apply only to accounts of perceptual content on which perceptual relations to the world play no explanatory role. With austere relationalists, I will argue that perceptual experience is fundamentally relational. But against austere relationalists, I will argue that it is fundamentally both relational and representational.     

An Empirical Examination of Symptom Substitution Associated With Behavior Therapy for Tourette's Disorder

Over the past six decades, behavior therapy has been a major contributor to the development of evidence-based psychotherapy treatments. However, a long-standing concern with behavior therapy among many nonbehavioral clinicians has been the potential risk for symptom substitution. Few studies have been conducted to evaluate symptom substitution in response to behavioral treatments, largely due to measurement and definitional challenges associated with treated psychiatric symptoms. Given the overt motor and vocal tics associated with Tourette’s disorder, it presents an excellent opportunity to empirically evaluate the potential risk for symptom substitution associated with behavior therapy. The present study examined the possible presence of symptom substitution using four methods: (a) the onset of new tic symptoms, (b) the occurrence of adverse events, (c) change in tic medications, and (d) worsening of co-occurring psychiatric symptoms. Two hundred twenty-eight participants with Tourette’s disorder or persistent motor or vocal tic disorders were randomly assigned to receive behavioral therapy or supportive therapy for tics. Both therapies consisted of eight sessions over 10 weeks. Results indicated that participants treated with behavior therapy were not more likely to have an onset of new tic symptoms, experience adverse events, increase tic medications, or have an exacerbation in co-occurring psychiatric symptoms relative to participants treated with supportive therapy. Further analysis suggested that the emergence of new tics was attributed with the normal waxing and waning nature of Tourette’s disorder. Findings provide empirical support to counter the long-standing concern of symptom substitution in response to behavior therapy for individuals with Tourette's disorder.     

A Hobbesian Theory of Shame

On most accounts present in the literature, the complex experience of shame has the injury to self‐esteem as its main component. A major objection to this idea is that it fails to differentiate between shame and disappointment in oneself. I argue that previous attempts to respond to the objection are unsatisfactory. I argue further that the distinction should refer to the different ways the subject's self‐esteem is formed. A necessary requirement for shame is that the standards and values by which the subject judges himself are borrowed from a canon of values the subject accepts as a given. The proper focus of shame is the fact of conformity to that canon. Those agents who have a different conception of self‐esteem and who freely set and alter their own values are prone to self‐disappointment, but not to shame.