Papers by Stephen R Jackson
medRxiv (Cold Spring Harbor Laboratory), Mar 6, 2023
International Review of Movement Disorders
Tourette syndrome (TS) is a neurological disorder of childhood onset characterised by the occurre... more Tourette syndrome (TS) is a neurological disorder of childhood onset characterised by the occurrence of vocal and motor tics. The pathophysiology of TS has been linked to dysfunction within cortical-striatal-thalamic-cortical (CSTC) brain circuits and alterations in gamma-aminobutyric acid (GABA) signalling within the striatum. Recently, it has been proposed that increased neural noise, leading to decreased signal-to-noise, may be responsible for dysfunctional information processing in TS. Importantly, increased neural noise could impact all stages of the sensorimotor processing, including sensation, action planning, and action execution, and it currently remains to be determined whether this ‘increased neural noise account’ of TS refers to all aspects of information processing, or is specific to particular stages of information processing. We hypothesised that if TS was associated with decreased signal-to-noise when processing visual stimuli, then this might be reflected in a reduc...
Tourette syndrome (TS) and chronic tic disorder (CTD) are neurological disorders of childhood ons... more Tourette syndrome (TS) and chronic tic disorder (CTD) are neurological disorders of childhood onset characterised by the occurrence of tics; repetitive, purposeless, movements or vocalisations of short duration which can occur many times throughout a day. Currently, effective treatment for tic disorders is an area of considerable unmet clinical need. We aimed to evaluate the efficacy of a home-administered neuromodulation treatment for tics involving the delivery of rhythmic pulse trains of median nerve stimulation (MNS) delivered via a wearable ‘watch-like’ device worn at the wrist. We conducted a UK-wide parallel double-blind sham-controlled trial for the reduction of tics in individuals with tic disorder. The device was programmed to deliver rhythmic (10Hz) trains of low-intensity (1-19 mA) electrical stimulation to the median nerve for a pre-determined duration each day, and was intended to be used by each participant in their home once each day, 5 days each week, for a period o...
International Review of Movement Disorders
Journal of Neurophysiology, 2021
Transcranial magnetic stimulation of the primary motor cortex (M1) is a promising treatment for c... more Transcranial magnetic stimulation of the primary motor cortex (M1) is a promising treatment for chronic pain, but its mechanism of action remains unclear. Competing dynamic causal models of effective connectivity between M1 and medial and lateral pain systems suggest direct input into the insular, anterior cingulate cortex, and parietal operculum. This supports the hypothesis that analgesia produced from M1 stimulation most likely acts through the activation of top-down processes associated with intracortical modulation.
Cortex, 2018
Tourette syndrome (TS) is a childhood-onset neurological condition characterised by an evolving r... more Tourette syndrome (TS) is a childhood-onset neurological condition characterised by an evolving repertoire of chronic motor tics and one or more phonic tics. Tics, like habits, are inflexible and repetitive behaviours that are acquired over a period of time. It has been proposed that tics arise in TS as a result of increased habit learning: which may bias the child to acquire automatic behaviours (i.e. tics) more readily than is normal and make it harder to unlearn maladaptive habits once they have been acquired. Using a well-established visuomotor adaptation task, we investigated motor learning in a group of children and adolescents with a clinical diagnosis of TS relative to a group of age and gender matched typically developing individuals. In particular, we quantified differences in the strength and quality of motor learning and unlearning in TS, and the consolidation of motor learning over a 24 hour washout period. We demonstrated that there was a marginally significant decrease in learning rate in the individuals with TS relative to age and gender matched typically developing controls. However, this effect was not associated with tic severity and could be entirely accounted for by the severity of cooccurring ADHD symptoms. Thus, once ADHD symptoms had been accounted for, there were no between group differences in learning rate or the degree of learning observed. By contrast, and more importantly, we found that following learning the rate of forgetting (unlearning) was significantly negatively associated with motor tic severity, such that individuals with more severe tics took longer to unlearn previously learnt motor patterns of behavior. This finding is consistent with the proposal that TS is associated with alterations in the striatal habit learning system and with the view that TS may make it harder to unlearn maladaptive motor habits once they have been acquired.
Clinical Neurophysiology, 2017
Journal of Child Psychology and Psychiatry, 2016
BackgroundTourette syndrome (TS) and chronic tic disorder (CTD) affect 1–2% of children and young... more BackgroundTourette syndrome (TS) and chronic tic disorder (CTD) affect 1–2% of children and young people, but the most effective treatment is unclear. To establish the current evidence base, we conducted a systematic review of interventions for children and young people.MethodsDatabases were searched from inception to 1 October 2014 for placebo‐controlled trials of pharmacological, behavioural, physical or alternative interventions for tics in children and young people with TS or CTD. Certainty in the evidence was assessed with the GRADE approach.ResultsForty trials were included [pharmacological (32), behavioural (5), physical (2), dietary (1)]. For tics/global score there was evidence favouring the intervention from four trials of α2‐adrenergic receptor agonists [clonidine and guanfacine, standardised mean difference (SMD) = −0.71; 95% CI −1.03, −0.40; N = 164] and two trials of habit reversal training (HRT)/comprehensive behavioural intervention (CBIT) (SMD = −0.64; 95% CI −0.99,...
Health technology assessment (Winchester, England), 2016
Tourette syndrome (TS) is a neurodevelopmental condition characterised by chronic motor and vocal... more Tourette syndrome (TS) is a neurodevelopmental condition characterised by chronic motor and vocal tics affecting up to 1% of school-age children and young people and is associated with significant distress and psychosocial impairment. To conduct a systematic review of the benefits and risks of pharmacological, behavioural and physical interventions for tics in children and young people with TS (part 1) and to explore the experience of treatment and services from the perspective of young people with TS and their parents (part 2). For the systematic reviews (parts 1 and 2), mainstream bibliographic databases, The Cochrane Library, education, social care and grey literature databases were searched using subject headings and text words for tic* and Tourette* from database inception to January 2013. For part 1, randomised controlled trials and controlled before-and-after studies of pharmacological, behavioural or physical interventions in children or young people (aged < 18 years) wit...
Cognitive Neuroscience, 2011
The intention to execute a movement can modulate our perception of sensory events; however, theor... more The intention to execute a movement can modulate our perception of sensory events; however, theoretical accounts of these effects, and also empirical data, are often contradictory. We investigated how perception of a somatosensory stimulus differed according to whether it was delivered to a limb being prepared for movement or to a nonmoving limb. Our results demonstrate that individuals perceive a somatosensory stimulus delivered to the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;moving&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; limb as occurring significantly later than when an identical stimulus is delivered to a &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;nonmoving&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; limb. Furthermore, human brain imaging (fMRI) analyses demonstrate that this modulation is accompanied by a significant decrease in BOLD signal in the right parietal operculum (SII) for stimuli delivered to the moving limb. These results indicate that during movement preparation a network of premotor brain areas may facilitate movement execution by attenuating the processing of behaviorally irrelevant signals within higher-order secondary somatosensory (SII) areas.
Journal of Neuropsychology, 2020
BackgroundPatients with Gilles de la Tourette syndrome (GTS) or chronic tic disorders frequently ... more BackgroundPatients with Gilles de la Tourette syndrome (GTS) or chronic tic disorders frequently experience premonitory urges prior to tics. The ‘Premonitory Urges for Tic Disorders Scale’ (PUTS) is commonly used in order to assess urge severity in patients with tics. Several studies suggest that the PUTS might measure more than one dimension of urges. These include the quality and severity of premonitory urges.MethodsThis study aims to replicate and extend previous findings concerning the psychometric properties of the PUTS and its underlying dimensions in a large sample of 241 patients with GTS including both adults (n = 93; mean age = 34.2 ± 12.84; 73 male) and minors (n = 148; mean age = 11.8 ± 2.86; 123 male), pooled from three different recruitment sites.ResultsData analysis confirmed good reliability across the PUTS items for both minors and adults and acceptable item characteristics for items 2–8. A factor analysis of items 1–8 confirmed the existence of two factors in both ...
Cortex, 2020
Previous observations of improvements in cognition in typically developing children following mod... more Previous observations of improvements in cognition in typically developing children following moderate to vigorous exercise (e.g. Budde, Voelcker-Rehage, Pietrabyk-Kendziorra, Ribeiro, and Tidow, 2008; Hillman et al., 2009) have led to increased interest in the potential benefits of exercise for children with neurodevelopmental disorders, involving difficulties in selfregulation (e.g. Halperin and Healy, 2011; Archer and Kostrzewa, 2012). Using a withinsample design, the current study looked at the beneficial effects of non-aerobic movement training (Tai Chi), compared to aerobic movement training (Kick Boxing), on behavioural measures of cognitive control and clinical measures of tic severity in a group of young people with Tourette Syndrome (TS). We demonstrate that Kick Boxing, but not Tai Chi, led to a significant enhancement in cognitive control task performance. Furthermore, while tic frequency (tics per minute) was reduced during both types of exercise, this reduction was significantly greater, and sustained for longer, following Kick Boxing. Importantly, the magnitude of the increase in cognitive control following Kick Boxing predicted the degree of reduction in tic frequency. These findings suggest that aerobic exercise may be a useful intervention for improving self-regulation of tics in young people with TS, probably through enhancements in associated cognitive control circuits.
Current Biology, 2006
Orientation selectivity without orientation maps in visual cortex of a highly visual mammal.
Behavioural Neurology, 2002
Patients with right unilateral cerebral stroke, four of which showed acute hemispatial neglect, a... more Patients with right unilateral cerebral stroke, four of which showed acute hemispatial neglect, and healthy aged-matched controls were tested for their ability to grasp objects located in either right or left space at near or far distances. Reaches were performed either in free vision or without visual feedback from the hand or target object. It was found that the patient group showed normal grasp kinematics with respect to maximum grip aperture, grip orientation, and the time taken to reach the maximum grip aperture. Analysis of hand path curvature showed that control subjects produced straighter right hand reaches when vision was available compared to when it was not. The right hemisphere lesioned patients, however, showed similar levels of curvature in each of these conditions. No behavioural differences, though, could be found between right hemisphere lesioned patients with or without hemispatial neglect on either grasp parameters, path deviation or temporal kinematics.
Brain, 2018
for a scientific commentary on this article. Current theories of motor control emphasize how the ... more for a scientific commentary on this article. Current theories of motor control emphasize how the brain may use internal models of the body to ensure accurate planning and control of movements. One such internal model-a forward model-is thought to generate an estimate of the next motor state and/or the sensory consequences of an upcoming movement, thereby allowing movement errors to be monitored. In addition, forward models may provide a means by which to determine a sense of agency, i.e. the (conscious) sense of authorship and control over our actions. Tourette syndrome is a developmental neurological condition characterized by the occurrence of motor and phonic tics. The involuntary (or voluntary) nature of tics has been the subject of considerable debate, and it was recently argued that the presence of tics in Tourette syndrome could result in a blurring of any subjective boundary between voluntary and involuntary movements. In particular, it was proposed that the level of sensorimotor noise that accompanies tics may be particularly high in Tourette syndrome, and this may contribute to less efficient forward models used to determine agency. We investigated whether the internal monitoring of movements is impaired in individuals with Tourette syndrome, relative to a matched group of typically developing individuals, using a task that involved executing double-step aiming movements using a hand-held robot manipulandum. Participants were required on each trial to execute two movements in turn, each directed to a remembered target location without visual feedback. Importantly, we assumed that to perform accurately on the second (return) movement it would be necessary to update any forward model to take into account errors made during the first (outward) movement. Here we demonstrate that while the Tourette syndrome group were equally accurate, and no more variable, than the matched control group in executing aiming movements to the first (outward) target location, they were significantly less accurate, and exhibited greater movement variability, than controls when executing the second (return) movement. Furthermore, we show that for the return movement only, movement accuracy and movement variability were significantly predicted by the Tourette syndrome group's clinical severity scores. We interpret these findings as consistent with the view that individuals with Tourette syndrome may experience a reduction in the precision of the forward model estimates thought necessary for the accurate planning and control of movements.
Cortex, 2020
Tourette syndrome (TS) is a neurological disorder of childhood onset that is characterised by the... more Tourette syndrome (TS) is a neurological disorder of childhood onset that is characterised by the occurrence of motor and vocal tics. TS is associated with corticalstriatal-thalamic-cortical circuit [CSTC] dysfunction and hyper-excitability of cortical limbic and motor regions that are thought to 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 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, not least because they form the core component in many behavioural therapies used in the treatment of tic disorders. Several lines of evidence indicate that the insular cortex may play a particularly important role in the generation of PU in TS and 'urges-for-action' more generally. In the current study we utilised voxel-based morphometry techniques together with 'seed-to-voxel' structural covariance network (SCN) mapping to investigate the putative role played by the right insular cortex in the generation of motor tics and the experience of PU in a relatively large group of young people TS. We demonstrate that clinical measures of motor tic severity and PU are uncorrelated with one another, that motor tic severity and PU scores are associated with separate regions of the insular cortex, and that the insula is associated with different structural covariance networks in individuals with TS compared to a matched group of typically developing individuals.
Cortex, 2020
In this study we employed voxel-based morphometry, and a 'seed-to-voxel' structural covariance ne... more In this study we employed voxel-based morphometry, and a 'seed-to-voxel' structural covariance network (SCN) mapping approach, to investigate alterations in GM cerebellar volume in people with TS, and alterations in cerebellar SCNs associated with TS. Data from 64 young participants was entered in the final analysis, of which 28 had TS while 36 were ageand sex-matched healthy volunteers. Using the spatially unbiased atlas template of the cerebellum and brainstem (SUIT) atlas, we found reduced GM volume in cerebellar lobule involved in higher-order cognitive functions and sensorimotor processing, in patients. In addition, we found that several areas located in frontal and cingulate cortices and sensorimotor network in addition to subcortical areas show altered structural covariance with our cerebellar seed compared to age-matched controls. These results add to the increasing evidence that cortico-basal ganglia-cerebellar interactions play an important role in tic symptomology.
Tourette syndrome (TS) and chronic tic disorder (CTD) are neurodevelopmental disorders that are c... more Tourette syndrome (TS) and chronic tic disorder (CTD) are neurodevelopmental disorders that are characterised by the occurrence of tics; repetitive, purposeless, movements or vocalisations of short duration which can occur many times throughout a day. One of the defining characteristics of tics, and one that distinguishes them from other kinds of abnormal movement, is that they can often be suppressed for a period of time. However, tic suppression is invariably associated with increasing levels of discomfort which is most often experienced as a strong urge-to-tic (PU). Importantly, PU are uncomfortable sensory phenomena, often described as feelings of discomfort or pressure which can be temporally reduced after tic execution. Individuals who experience PU often report that: these experiences are more bothersome than their tics; that expressing their tics give them relief from, and temporarily abolishes, their PU; and that they would not exhibit tics if they did not experience PU. Fo...
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Papers by Stephen R Jackson