Julius Verrel

University of Lübeck · Institute of Systems Motor Science

Functional movement disorders (FMD) are amongst the most common and disabling neurological conditions, placing a significant burden on the healthcare system. Despite the frequency and importance of FMD, our understanding of the underlying pathophysiology is limited, hindering the development of causal treatment options. Traditionally, FMD was consi...

Background The occurrence of tics is the main basis for the diagnosis of Gilles-de-la-Tourette syndrome (GTS). Video-based tic assessments are time-consuming. Objectives To assess the potential of automated video-based tic detection for discriminating between videos of adults with GTS and healthy control (HC) participants. Methods The amount and...

Background: Although functional neurological movement disorders (FMD) are characterized by motor symptoms, sensory processing has also been shown to be disturbed. However, how the integration of perception and motor processes, essential for the control of goal-directed behavior, is altered in patients with FMD is less clear. A detailed investigati...

Increased activity in the left inferior parietal cortex (BA40) plays a role in the generation of tics in Gilles de la Tourette syndrome (GTS). Thus, inhibitory repetitive transcranial magnetic stim-ulation (rTMS) applied to BA40 was hypothesized to alleviate symptoms in GTS. We investigat-ed the immediate effects of single-session 1Hz rTMS and sham...

We can monitor our intentional movements and form explicit representations about our movements, allowing us to describe how we move our bodies. But it is unclear which information this metacognitive monitoring relies on. For example, when throwing a ball to hit a target, we might use the visual information about how the ball flew to metacognitively...

Background: Motor symptoms in functional movement disorders (FMDs) are experienced as involuntary but share characteristics of voluntary action. Clinical and experimental evidence indicate alterations in monitoring, control, and subjective experience of self-performed movements. Objective: The objective of this study was to test the prediction t...

Premonitory urges preceding tics are a cardinal feature of Gilles de la Tourette syndrome (GTS), a developmental disorder usually starting during middle childhood. However, the temporal relation between urges and tics has only been investigated in adults. In 25 children and adolescents with GTS (8-18 years), we assess urge-tic associations, includi...

Dopa-responsive dystonia (DRD) is caused by impaired dopamine biosynthesis due to a GTP-cyclohydrolase-1 (GCH1) deficiency, resulting in a combination of dystonia and parkinsonism. However, the effect of GCH1 mutations and levodopa treatment on motor control beyond simple movements, such as timing, action preparation and feedback processing, have n...

Tourette syndrome (TS) is characterized by multiple motor and vocal tics, and high-comorbidity rates with other neuropsychiatric disorders. Obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), major depressive disorder (MDD), and anxiety disorders (AXDs) are among the most prevalent...

As humans we communicate important information through fine nuances in our facial expressions, but because conscious motor representations are noisy, we might not be able to report these fine movements. Here we measured the precision of the explicit metacognitive information that young adults have about their own facial expressions. Participants im...

We can monitor our intentional movements, in order to describe how we move our bodies. But it is unclear which information this metacognitive monitoring relies on. For example, when throwing a ball to hit a target, we might use the visual information about how the ball flew to metacognitively assess our performance. Alternatively, we might disregar...

Background Currently, there is a marked increase of young people with sudden onset of tic-like behaviors resembling movements and vocalizations presented on social media videos as “Tourette syndrome”. Objectives To delineate clinical phenomenology of tic-like behaviors following social media exposure in comparison to clinical features of Tourette...

It is a common phenomenon that somatosensory sensations can trigger actions to alleviate experienced tension. Such “urges” are particularly relevant in patients with Gilles de la Tourette (GTS) syndrome since they often precede tics, the cardinal feature of this common neurodevelopmental disorder. Altered sensorimotor integration processes in GTS a...

Premonitory urges are a cardinal feature in Tourette syndrome (GTS) and are commonly viewed as a driving force of tics. However, inter-individual differences in experimentally measured urges, tics and urge-tic associations, as well as possible relations to clinical characteristics and abnormal perception-action processing recently demonstrated in t...

We can make exquisitely precise movements without the apparent need for conscious monitoring. But can we monitor the low-level movement parameters when prompted? And what are the mechanisms that allow us to monitor our movements? To answer these questions, we designed a semivirtual ball throwing task. On each trial, participants first threw a virtu...

Dystonia is conceptualized as a network disorder involving basal ganglia, thalamus, sensorimotor cortex and the cerebellum. The cerebellum has been implicated in dystonia pathophysiology, but studies testing cerebellar function in dystonia patients have provided equivocal results. This study aimed to further elucidate motor network deficits in cerv...

As humans we communicate important information through fine nuances in our facial expressions, but because conscious motor representations are noisy, we might not be able to report these fine but meaningful movements. Here we measured how much explicit metacognitive information young adults have about their own facial expressions. Participants imit...

Because tics are the defining clinical feature of Tourette syndrome, it is conceptualized predominantly as a motor disorder. There is some evidence though suggesting that the neural basis of Tourette syndrome is related to perception-action processing and binding between perception and action. However, binding processes have not been examined in th...

Action control requires precisely and flexibly linking sensory input and motor output. This is true for both, visuo-motor and somatosensory-motor integration. However, while perception-action integration has been extensively investigated for the visual modality, data on how somatosensory and action-related information is associated are scarce. We u...

Current theories in cognitive neuroscience assume that internal simulation, i.e., the reproduction of brain activity underlying another person’s inner state and behaviour in the perceiver’s brain, plays an important role in understanding others. Here we test the prediction that common neural activity during facial communication of affect leads to i...

We can make exquisitely precise movements without the apparent need for conscious monitoring. But can we monitor the low-level movement parameters when prompted? And what are the mechanisms that allow us to monitor our movements? To answer these questions, we designed a semi-virtual ball throwing task. On each trial, participants first threw a virt...

Gilles de la Tourette syndrome is a multifaceted neurodevelopmental disorder characterized by multiple motor and vocal tics. Research in Tourette syndrome has traditionally focused on the motor system. However, there is increasing evidence for perceptual and cognitive processes to play a crucial role as well. Against this background it has been rea...

Skin picking is a newly recognized obsessive-compulsive spectrum disorder in DSM-5. Similar to some repetitive behaviors in Gilles de la Tourette syndrome (GTS) and obsessive-compulsive disorder (OCD), premonitory urges are assumed to play a critical role in maintaining skin picking behavior, by creating a vicious cycle. The present study is the fi...

Syllables are thought to be processing units in handwritten word production. Yet, little is known about whether the orthographic characteristics of different languages influence syllabic processing during handwriting, which is critical for the evaluation and further development of extant models of handwritten language production. In the present stu...

The important role of the supplementary motor area (SMA) in the generation of tics and urges in Gilles de la Tourette syndrome (GTS) is underscored by an increased SMA-motor cortex (M1) connectivity. However, whether plasticity is also altered in SMA-M1 pathways is unclear. We explored whether SMA-M1 plasticity is altered in patients with Tourette...

Background: The introduction of low cost optical 3D motion tracking sensors provides new options for effective quantification of motor dysfunction. Objective: The present study aimed to evaluate the Kinect V2 sensor against a gold standard motion capture system with respect to accuracy of tracked landmark movements and accuracy and repeatability...

Evidence for experience-dependent structural brain change in adult humans is accumulating. However, its time course is not well understood, as intervention studies typically consist of only 2 imaging sessions (before vs. after training). We acquired up to 18 structural magnetic resonance images over a 7-week period while 15 right-handed participant...

Sudden application of load along a sagittal or coronal axis has been used to study trunk stiffness, but not axial (vertical) load. This study introduces a new method for sudden-release axial load perturbation. Prima facie validity was supported by comparison with standard mechanical systems. We report the response of the human body to axial perturb...

We use functional magnetic resonance imaging to investigate short-term neural effects of a brief sensorimotor intervention adapted from the Feldenkrais method, a movement-based learning method. Twenty-one participants (10 men, 19–30 years) took part in the study. Participants were in a supine position in the scanner with extended legs while an expe...

The dual-process account of sensorimotor-cognitive interactions postulates that easy cognitive tasks can lead to performance improvements in the motor domain (e.g., an increased stability while walking or balancing) across the lifespan. However, cross-domain resource competition can lead to performance decrements in motor tasks when the concurrent...

Stringed instrument bowing is a complex coordinative motor skill acquired though years of intense practice. We apply a novel “freezing” analysis to investigate how movement at different joints contributes to bow transport (movement amplitude), stabilization of bow parameters (angle, velocity) during bow movements, and quick reversals of bow directi...

We investigated lexical decision making in children and adults by analyzing spatiotemporal characteristics of responses involving a hand movement. Children's and adults' movement trajectories were assessed in three tasks: a lexical decision task (LDT), a pointing task that involved minimal cognitive processing, and a symbol task requiring a simple...

Touching one's own body provides haptic feedback about the spatial configuration and movement of body parts. However, the influence of self-touch on movement performance has not been investigated so far. The authors evaluated the contribution of self-touch by asking participants to perform cyclic movement sequences with their feet while touching th...

Theoretical and empirical evidence suggests that accurate and efficient motor performance may be achieved by task-specific exploitation of biomechanical degrees of freedom. We investigate coordination of the right arm in a task requiring a sudden yet precisely controlled reversal of movement direction: bow reversals during continuous (“legato”) ton...

Stable walking depends on the coordination of multiple biomechanical degrees of freedom to ensure the dynamic maintenance of whole-body equilibrium as well as continuous forward progression. We investigated adult age-related differences in whole-body coordination underlying stabilization of center of mass (CoM) position and step pattern during loco...

Stringed instrument bowing is a complex sensorimotor skill, involving fine regulation of bow orientation and motion relative to the string. In this study, we characterize this skill in terms of stabilization of specific bow parameters as well as the underlying use and coordination of the degrees of freedom (DOF) of the right bowing arm. Age-matched...

Theoretical and empirical work indicates that the central nervous system is able to stabilize motor performance by selectively suppressing task-relevant variability (TRV), while allowing task-equivalent variability (TEV) to occur. During unperturbed bipedal standing, it has previously been observed that, for task variables such as the whole-body ce...

Depending upon its organization, movement variability may reflect poor or flexible control of a motor task. We studied adult age-related differences in the structure of postural variability in manual pointing using the uncontrolled manifold (UCM) method. Participants from 2 age groups (younger: 20-30 years; older: 70-80 years; 12 subjects per group...

Different analysis methods have been developed for assessing motor-equivalent organization of movement variability. In the uncontrolled manifold (UCM) method, the structure of variability is analyzed by comparing goal-equivalent and non-goal-equivalent variability components at the level of elemental variables (e.g., joint angles). In contrast, in...

Neck muscle vibration (NMV) during upright standing is known to induce forward leaning, which has been explained as a global response to the (illusory) perception of a lengthening of the dorsal neck muscles. However, the effects of NMV both at the level of individual joints and on whole-body postural coordination, and its potential modulation by vi...

We investigated motor-equivalent stabilization of task-related variables (TRV) at times of heel strike in eight healthy young men (23-30 years) who walked on a motorized treadmill at self-selected and prescribed speeds within the normal walking speed range. The TRV consisted of step parameters (step length and width) and the center of mass (CoM) po...

In the uncontrolled manifold (UCM) approach, variability in elemental variables (such as joint angles or muscle modes) is decomposed into goal-equivalent and non-goal-equivalent variability components (GEV, NGEV) with regard to a specified task variable. A UCM effect is present, when GEV exceeds NGEV, and different indices have been proposed to qua...

With advancing adult age, sensorimotor functioning, spatial processing, and the motivation to explore new environments decline, leading to impaired spatial navigation skills. Using a controlled virtual-world laboratory equipped with a treadmill interface, we examined how assistive navigation technologies differing in cognitive demand affect walking...

We assessed age-related differences in adults in familiarization to treadmill walking within virtual environments (VE), and examined whether treadmill walking after familiarization resembles overground walking. Seventeen younger and 17 older adults walked at preferred speed on an overground walkway and afterwards walked at the same speed for 20 min...

We investigated effects of concurrent cognitive task difficulty (n-back) on the regularity of whole-body movements during treadmill walking in women and men from 3 age groups (20-30, 60-70, and 70-80 years old). Using principal component analysis of individual gait patterns, we separated main (regular) from residual (irregular) components of whole-...

In the present study we investigated eye-hand coordination in adolescents with hemiparetic cerebral palsy (CP) and neurologically healthy controls. Using an object prehension and transport task, we addressed two hypotheses, motivated by the question whether early brain damage and the ensuing limitations of motor activity lead to general and/or effe...

Cerebral Palsy (CP) is a broad definition of a neurological condition in which disorders in movement execution and postural control limit the performance of activities of daily living. In this paper, we first review studies on motor planning in hemiplegic CP. Second, preliminary data of a recent study on eye-hand coordination in participants with h...