Persistent combined type sleep-related rhythmic movement disorder into adolescence: a case report.

SRMD is characterized by repetitive, stereotyped, rhythmic movements of large muscle groups, primarily occurring at the onset of sleep and during sleep. Common in infancy and early childhood, its persistence into adolescence or adulthood is rare. Combined type is rare. This article reviews and analyzes the diagnosis and treatment of a case with combined type SRMD persisting for 15 years aimed at enhancing the level of diagnosis and treatment of the disorder, and reducing misdiagnosis and missed diagnosis.

Automatic detection of foot-strike onsets in a rhythmic forelimb movement.

Rhythmic movement is the fundamental motion dynamics characterized by repetitive patterns. Precisely defining onsets in rhythmic movement is essential for a comprehensive analysis of motor functions. Our study introduces an automated method for detecting rat's forelimb foot-strike onsets using deep learning tools. This method demonstrates high accuracy of onset detection by combining two techniques using joint coordinates and behavioral confidence scale. The analysis extends to neural oscillatory responses in the rat's somatosensory cortex, validating the effectiveness of our combined approach. Our technique streamlines experimentation, demanding only a camera and GPU-accelerated computer. This approach is applicable across various contexts and promotes our understanding of brain functions during rhythmic movements.

Reduced learning rates but successful learning of a coordinated rhythmic movement by older adults.

Previous work has investigated the information-based mechanism for learning and transfer of learning in coordinated rhythmic movements. In those papers, we trained young adults to produce either 90° or 60° and showed in both cases that learning entailed learning to use relative position as information for the relative phase. This variable then supported transfer of learning to untrained coordinations +/30° on either side. In this article, we replicate the 90° study with younger adults and extend it by training older adults (aged between 55 and 65 years). Other work has revealed a steep decline in learning rate around this age, and no follow-up study has been able to successfully train older adults to perform a novel coordination. We used a more intensive training paradigm and showed that while older adult learning rates remain about half that of younger adults, given time they are able to acquire the new coordination. They also learn to use relative position, and consequently show the same pattern of transfer. We discuss implications for attempts to model the process of learning in this task.

Sing to me, baby: Infants show neural tracking and rhythmic movements to live and dynamic maternal singing.

Infant-directed singing has unique acoustic characteristics that may allow even very young infants to respond to the rhythms carried through the caregiver's voice. The goal of this study was to examine neural and movement responses to live and dynamic maternal singing in 7-month-old infants and their relation to linguistic development. In total, 60 mother-infant dyads were observed during two singing conditions (playsong and lullaby). In Study 1 (n = 30), we measured infant EEG and used an encoding approach utilizing ridge regressions to measure neural tracking. In Study 2 (n =40), we coded infant rhythmic movements. In both studies, we assessed children's vocabulary when they were 20 months old. In Study 1, we found above-threshold neural tracking of maternal singing, with superior tracking of lullabies than playsongs. We also found that the acoustic features of infant-directed singing modulated tracking. In Study 2, infants showed more rhythmic movement to playsongs than lullabies. Importantly, neural coordination (Study 1) and rhythmic movement (Study 2) to playsongs were positively related to infants' expressive vocabulary at 20 months. These results highlight the importance of infants' brain and movement coordination to their caregiver's musical presentations, potentially as a function of musical variability.

Sleep related rhythmic movement disorder: phenotypic characteristics and treatment response in a paediatric cohort.

OBJECTIVE: To describe phenotypic, polysomnographic characteristics, impact, and treatment response in children with sleep related rhythmic movement disorder (SR-RMD). BACKGROUND: There is limited research on SR-RMD. We have developed a systematic clinical evaluation of children with SR-RMD to improve understanding and treatment. METHODS: A retrospective chart review of 66 children at a UK tertiary hospital. Baseline assessment included validated screening questionnaires to study autism spectrum characteristics, general behaviour and sensory profile. A standardised questionnaire assessed impact on sleep quality and daytime wellbeing of child and family. Polysomnography data were collated. RESULTS: Children were aged 0.9-16.3 years (78.8% male). 51.5% had a neurodevelopmental disorder, most commonly autism spectrum disorder. High rates of behavioural disturbance and sensory processing differences were reported, not confined to children with neurodevelopmental disorders. Parents reported concerns about risk of injury, loss of sleep and persistence into adulthood. Daytime wellbeing was affected in 72% of children and 75% of other family members. Only 31/48 children demonstrated rhythmic movements during video-polysomnography, occupying on average 6.1% of time in bed. Most clusters occurred in the settling period but also arose from N1, N2 and REM sleep and wake after sleep onset. Melatonin was prescribed to 52 children, all but one were extended-release preparations. 24/27 children with available data were reported to improve with melatonin. CONCLUSIONS: SR-RMD places a significant burden on child and family wellbeing. Our novel findings of sensory processing differences in this population and parent reported therapeutic response to extended-release melatonin offer potential avenues for future research.

Premotor function in interpersonal bimanual coordination: Neural responses to varying frequencies and spatio-temporal relationships.

BACKGROUND: Interpersonal movement coordination is an important aspect of daily life. Behavioral studies have found that rhythmic bimanual coordination of movement is mainly influenced by two factors, spatio-temporal relationship and frequency of movements. How these factors affect action coordination at the neural level needs further exploration. The current study used a factor design to investigate the brain basis of movement coordination under various spatiotemporal relationships and frequencies, as well as their intricate interaction. METHODS: Participants were asked to perform symmetric or alternating hand movements under conditions of different spatio-temporal relationships (symmetric, alternating) and frequencies. A multi-channel, continuous wave, functional near-infrared spectral (fNIRS) imaging instrument was used to monitor hemodynamic activity while 16 pairs of volunteers performed the task. RESULTS: Behaviorally, as indexed by phase locking value, movements were more stable in symmetric mode than in alternate mode. With increasing frequency, symmetric mode became more unstable; in contrast, alternating mode became more stable at higher frequencies, suggesting phase transition. Activation in brain regions of interest was much stronger in symmetric mode as compared with alternate mode. In alternate mode, but not symmetric mode, [HbO] varied with frequency. CONCLUSION: Interpersonal bimanual coordination involves activity in premotor areas (premotor cortex, supplementary motor area, and frontal eye fields). More oxygen is consumed in these regions in alternating mode than in symmetric mode.

Sleep-related rhythmic movement disorder in children: a mini-review.

Sleep-related rhythmic movement disorder (SRRMD) occurs in both infants and children. This disorder rarely occurs or persists in adolescence or adulthood. Rhythmic movement during sleep in children is often asymptomatic and considered a benign condition. It is classified as SRRMD when movement significantly disrupts sleep, results in daytime functional impairment, or causes self-inflicted body injury. Several studies have demonstrated that SRRMD occurs in all sleep stages. Few studies have investigated rhythmic movement disorder (RMD) in children. SRRMD is a clinical diagnosis supported by home video recordings. When the clinical history is insufficient to provide a definitive diagnosis of SRRMD, and other sleep-related conditions or seizure disorders are suspected, video-polysomnography is indicated. There are currently no clinical guidelines for treating SRRMD.

Atypical head banging developed in teens persisting into adulthood as sleep-related rhythmic movement disorder.

Head banging is one subtype of sleep-related rhythmic movement disorder, characterized by stereotyped, repetitive rhythmic movements, such as lifting the head or entire upper body, banging the frontal area hard on the pillow, or slamming the occiput against a headboard. An atypical form of head banging with punching or slapping the head with a hand is extremely rare, with only 4 such cases reported so far. Herein, we present a young adult male who, since his early teens, has had atypical head banging, also called head-slapping, and discuss the neuropsychological and polysomnographic findings and review the literature. CITATION: Ji K-H, Kang M-R, Kim SJ. Atypical head banging developed in teens persisting into adulthood as sleep-related rhythmic movement disorder. J Clin Sleep Med. 2023;19(5):999-1001.

Coupled and Synchronization Models of Rhythmic Arm Movement in Planar Plane.

Nonlinear dynamics have become a new perspective on model human movement variability; however, it is still a debate whether chaotic behavior is indeed possible to present during a rhythmic movement. This paper reports on the nonlinear dynamical behavior of coupled and synchronization models of a planar rhythmic arm movement. Two coupling schemes between a planar arm and an extended Duffing-Van der Pol (DVP) oscillator are investigated. Chaos tools, namely phase space, Poincare section, Lyapunov Exponent (LE), and heuristic approach are applied to observe the dynamical behavior of orbit solutions. For the synchronization, an orientation angle is modeled as a single well DVP oscillator implementing a Proportional Derivative (PD)-scheme. The extended DVP oscillator is used as a drive system, while the orientation angle of the planar arm is a response system. The results show that the coupled system exhibits very rich dynamical behavior where a variety of solutions from periodic, quasi-periodic, to chaotic orbits exist. An advanced coupling scheme is necessary to yield the route to chaos. By modeling the orientation angle as the single well DVP oscillator, which can synchronize with other dynamical systems, the synchronization can be achieved through the PD-scheme approach.

From thinking fast to moving fast: motor control of fast limb movements in healthy individuals.

The ability to produce high movement speeds is a crucial factor in human motor performance, from the skilled athlete to someone avoiding a fall. Despite this relevance, there remains a lack of both an integrative brain-to-behavior analysis of these movements and applied studies linking the known dependence on open-loop, central control mechanisms of these movements to their real-world implications, whether in the sports, performance arts, or occupational setting. In this review, we cover factors associated with the planning and performance of fast limb movements, from the generation of the motor command in the brain to the observed motor output. At each level (supraspinal, peripheral, and motor output), the influencing factors are presented and the changes brought by training and fatigue are discussed. The existing evidence of more applied studies relevant to practical aspects of human performance is also discussed. Inconsistencies in the existing literature both in the definitions and findings are highlighted, along with suggestions for further studies on the topic of fast limb movement control. The current heterogeneity in what is considered a fast movement and in experimental protocols makes it difficult to compare findings in the existing literature. We identified the role of the cerebellum in movement prediction and of surround inhibition in motor slowing, as well as the effects of fatigue and training on central motor control, as possible avenues for further research, especially in performance-driven populations.

Isolated mandibular sleep-related rhythmic movement disorder: A case report.

Background: Rhythmic masticatory muscle activity (RMMA) in sleep is usually not considered pathological unless associated with bruxism. On the other hand, so-called sleep-related rhythmic movement disorders (SRRMD) are a recognized category of sleep disorders, which involve prolonged rhythmic activity of large muscle groups, such as the whole body, the head, or a limb, but typically not the masticatory muscles.Clinical Presentation: A polysomnographic description of a patient with symptomatic RMMA without bruxism, fulfilling the diagnostic criteria of an SRRMD, is presented. The symptoms were initially misdiagnosed as bruxism and then as sleep-related epilepsy, which delayed an adequate treatment. Therapy of the comorbid obstructive sleep apnea with a positive airway pressure device (APAP) led to a self-reported improvement.Conclusion: The differential diagnosis of jaw movement in sleep is vast; a correct diagnosis is of the essence for adequate treatment. The prevalence of isolated RMMA resulting in perturbation of sleep warrants further exploration.

Sleep-Related Rhythmic Movement Disorder in Young Children with Down Syndrome: Prevalence and Clinical Features.

Sleep-related Rhythmic Movement Disorder (RMD) affects around 1% of UK pre-school children. Little is known about RMD in Down syndrome (DS). We aimed to determine: (a) the prevalence of RMD in children with DS aged 1.5-8 years; (b) phenotypic and sleep quality differences between children with DS and RMD and sex- and age-matched DS controls; and (c) night-to-night variability in rhythmic movements (RMs). Parents who previously reported RMs from a DS research registry of 202 children were contacted. If clinical history suggested RMD, home videosomnography (3 nights) was used to confirm RMs and actigraphy (5 nights) was used to assess sleep quality. Phenotype was explored by demographic, strengths and difficulties, Q-CHAT-10/social communication and life events questionnaires. Eight children had confirmed RMD. Minimal and estimated maximal prevalence were 4.10% and 15.38%, respectively. Sleep efficiency was significantly lower in RMD-cases (69.1%) versus controls (85.2%), but there were no other phenotypic differences. There was considerable intra-individual night-to-night variability in RMs. In conclusion, RMD has a high prevalence in children with DS, varies from night to night and is associated with poor sleep quality but, in this small sample, no daytime phenotypic differences were found compared to controls. Children with DS should be screened for RMD, which is amenable to treatment.

Freely chosen cadence during ergometer cycling is dependent on pedalling history.

PURPOSE: History dependence can refer to the fact that parts of the human physiology (e.g., one or a group of muscles, or the nervous system) as well as functional aspects of the human (e.g., motor behaviour, or performance) depend on prior muscle activation. In the present study, it was investigated whether initial cycling at relatively low and high preset target cadences affected a subsequent freely chosen cadence at the end of the same bout of submaximal ergometer cycling. METHODS: Twenty-two participants performed a single test session, which consisted of separate bouts of submaximal ergometer cycling. In one bout, cycling at 50 rpm was followed by cycling at freely chosen cadence. In another bout, cycling at 90 rpm was followed by cycling at freely chosen cadence. In yet another bout (denoted reference), the cadence was freely chosen throughout. Behavioural (cadence), biomechanical (tangential pedal force), and physiological (heart rate) responses were measured. RESULTS: Increased cadence resulted in decreased maximal tangential pedal force in accordance with existing knowledge. Initial cycling at 50 and 90 rpm caused freely chosen cadence to be about 5% lower and higher, respectively, than the freely chosen cadence (72.4 ± 2.4 rpm) at the end of the reference bout. These differences in cadence were not accompanied by statistically significant differences in heart rate. CONCLUSION: The freely chosen cadence depended on the preset cadence applied at the beginning of the bout. This was denoted a phenomenon of motor behavioural history dependence.

Phase-Dependent Crossed Inhibition Mediating Coordination of Anti-phase Bilateral Rhythmic Movement: A Mini Review.

The activity of the left and right central pattern generators (CPGs) is efficiently coordinated during locomotion. To achieve this coordination, the interplay between the CPG controlling one leg and that controlling another must be present. Previous findings in aquatic vertebrates and mammalians suggest that the alternate activation of the left and right CPGs is mediated by the commissural interneurons crossing the midline of the spinal cord. Especially, V0 commissural interneurons mediate crossed inhibition during the alternative activity of the left and right CPGs. Even in humans, phase-dependent modulation of the crossed afferent inhibition during gait has been reported. Based on those previous findings, crossed inhibition of the CPG in one leg side caused by the activation of the contralateral CPG is a possible mechanism underlying the coordination of the anti-phase rhythmic movement of the legs. It has been hypothesized that the activity of the flexor half center in the CPG inhibits the contralateral flexor half center, but crossed inhibition of the extensor half center is not present because of the existence of the double limb support during gait. Nevertheless, previous findings on the phase-dependent crossed inhibition during anti-phase bilateral movement of the legs are not in line with this hypothesis. For example, extensor activity caused crossed inhibition of the flexor half center during bilateral cycling of the legs. In another study, the ankle extensor was inhibited at the period switching from extension to flexion during anti-phase rhythmic movement of the ankles. In this review article, I provide a critical discussion about crossed inhibition mediating the coordination of the anti-phase bilateral rhythmic movement of the legs.

Images: Rhythmic movement disorder in a normal developing child with obstructive sleep apnea.

CITATION: Children can exhibit a plethora of strange movements during sleep. Asymptomatic rhythmic movements of the head, neck, and trunk can be normal. When these interfere with sleep or cause self-injury, it is pathologic and termed rhythmic movement disorder. CITATION: Bishara J, Mitacek R. Images: Rhythmic movement disorder in a normal developing child with obstructive sleep apnea. J Clin Sleep Med. 2021;17(10):2137-2139.

Sleep-Related Rhythmic Movement Disorder.

Sleep-related rhythmic movements disorder (SRRMD), typically considered a benign pediatric sleep disorder, comprise a group of movement disorders that occur predominantly early in childhood with an average age of onset of 9 months of age. Although it usually resolves spontaneously as the child ages, it can persist into adulthood. In this article, the authors review the identification, diagnosis, and management of SRRMD in children and adults.

Descending and Ascending Signals That Maintain Rhythmic Walking Pattern in Crickets.

The cricket is one of the model animals used to investigate the neuronal mechanisms underlying adaptive locomotion. An intact cricket walks mostly with a tripod gait, similar to other insects. The motor control center of the leg movements is located in the thoracic ganglia. In this study, we investigated the walking gait patterns of the crickets whose ventral nerve cords were surgically cut to gain an understanding of how the descending signals from the head ganglia and ascending signals from the abdominal nervous system into the thoracic ganglia mediate the initiation and coordination of the walking gait pattern. Crickets whose paired connectives between the brain and subesophageal ganglion (SEG) (circumesophageal connectives) were cut exhibited a tripod gait pattern. However, when one side of the circumesophageal connectives was cut, the crickets continued to turn in the opposite direction to the connective cut. Crickets whose paired connectives between the SEG and prothoracic ganglion were cut did not walk, whereas the crickets exhibited an ordinal tripod gait pattern when one side of the connectives was intact. Crickets whose paired connectives between the metathoracic ganglion and abdominal ganglia were cut initiated walking, although the gait was not a coordinated tripod pattern, whereas the crickets exhibited a tripod gait when one side of the connectives was intact. These results suggest that the brain plays an inhibitory role in initiating leg movements and that both the descending signals from the head ganglia and the ascending signals from the abdominal nervous system are important in initiating and coordinating insect walking gait patterns.

On the Multimodal Path to Language: The Relationship Between Rhythmic Movements and Deictic Gestures at the End of the First Year.

The aim of this study is to analyze the relationship between rhythmic movements and deictic gestures at the end of the first year of life, and to focus on their unimodal or multimodal character. We hypothesize that multimodal rhythmic movement performed with an object in the hand can facilitate the transition to the first deictic gestures. Twenty-three children were observed at 9 and 12 months of age in a naturalistic play situation with their mother or father. Results showed that rhythmic movements with objects in the hand are a frequent behavior in children's repertoires. Rhythmic behaviors tend to decrease from 9 to 12 months, specifically when they are unimodal. Multimodal rhythmic behavior production at 9 months is positively related with proximal deictic gestures 3 months later. Multimodal rhythmic movements are not directly related to distal deictic gestures, but are indirectly related via proximal deictic gestures. These results highlight the relevance of multimodal behaviors in the transition to the use of early gestures, and can be considered as a transitional phenomenon between the instrumental action and early communicative gestures.

A Re-Appraisal of the Effect of Amplitude on the Stability of Interlimb Coordination Based on Tightened Normalization Procedures.

The stability of rhythmic interlimb coordination is governed by the coupling between limb movements. While it is amply documented how coordinative performance depends on movement frequency, theoretical considerations and recent empirical findings suggest that interlimb coupling (and hence coordinative stability) is actually mediated more by movement amplitude. Here, we present the results of a reanalysis of the data of Post, Peper, and Beek (2000), which were collected in an experiment aimed at teasing apart the effects of frequency and amplitude on coordinative stability of both steady-state and perturbed in-phase and antiphase interlimb coordination. The dataset in question was selected because we found indications that the according results were prone to artifacts, which may have obscured the potential effects of amplitude on the post-perturbation stability of interlimb coordination. We therefore redid the same analysis based on movement signals that were normalized each half-cycle for variations in oscillation center and movement frequency. With this refined analysis we found that (1) stability of both steady-state and perturbed coordination indeed seemed to depend more on amplitude than on movement frequency per se, and that (2) whereas steady-state antiphase coordination became less stable with increasing frequency for prescribed amplitudes, in-phase coordination became more stable at higher frequencies. Such effects may have been obscured in previous studies due to (1) unnoticed changes in performed amplitudes, and/or (2) artifacts related to inappropriate data normalization. The results of the present reanalysis therefore give cause for reconsidering the relation between the frequency, amplitude, and stability of interlimb coordination.

Dynamic properties of VDP-CPG model in rhythmic movement with delay.

In this paper, Van Der Pol (VDP) oscillators are used as the output signal of central pattern generator (CPG), and a VDP-CPG network system of quadruped with four primary gaits (walk, trot, pace and bound) is established. The existence conditions of Hopf bifurcations for VDP-CPG systems corresponding to four primary gaits are given, and the coupling strength ranges between oscillators for four gaits are obtained. Numerical simulations are used to support theoretical analysis.