Analysis of functional networks involved in motor execution and motor imagery using combined hierarchical clustering analysis and independent component analysis

Cognitive experiments involving motor execution (ME) and motor imagery (MI) have been intensively studied using functional magnetic resonance imaging (fMRI). However, the functional networks of a multitask paradigm which include ME and MI were not widely explored. In this article, we aimed to investigate the functional networks involved in MI and ME using a method combining the hierarchical clustering analysis (HCA) and the independent component analysis (ICA). Ten right-handed subjects were recruited to participate a multitask experiment with conditions such as visual cue, MI, ME and rest. The results showed that four activation clusters were found including parts of the visual network, ME network, the MI network and parts of the resting state network. Furthermore, the integration among these functional networks was also revealed. The findings further demonstrated that the combined HCA with ICA approach was an effective method to analyze the fMRI data of multitasks.

The long term effects of sports concussion on retired Australian football players: a study using Transranial Magnetic Stimulation

This study investigated corticomotor excitability and inhibition, cognitive functioning, and fine motor dexterity in retired elite and amateur Australian football (AF) players who had sustained concussions during their playing careers. Forty male AF players who played at the elite level (n=20; mean age 49.7±5.7 years) or amateur level (n=20; mean age 48.4±6.9 years), and had sustained on average 3.2 concussions 21.9 years previously, were compared with 20 healthy age-matched male controls (mean age 47.56±6.85 years). All participants completed assessments of fine dexterity, visuomotor reaction time, spatial working memory (SWM), and associative learning (AL). Transcranial magnetic stimulation (TMS) was used to measure corticospinal excitability: stimulus-response (SR) curves and motor evoked potential (MEP) 125% of active motor threshold (aMT); and intracortical inhibition: cortical silent period (cSP), short-interval intracortical inhibition (SICI), and long-interval intracortical inhibition (LICI). Healthy participants performed better in dexterity (p=0.003), reaction (p=0.003), and movement time (p=0.037) than did both AF groups. Differences between AF groups were found in AL (p=0.027) and SWM (p=0.024). TMS measures revealed that both AF groups showed reduced cSP duration at 125% aMT (p>0.001) and differences in SR curves (p>0.001) than did healthy controls. Similarly, SICI (p=0.012) and LICI (p=0.009) were reduced in both AF groups compared with controls. Regression analyses revealed a significant contribution to differences in motor outcomes with the three measures of intracortical inhibition. The measures of inhibition differed, however, in terms of which performance measure they had a significant and unique predictive relationship with, reflecting the variety of participant concussion injuries. This study is the first to demonstrate differences in motor control and intracortical inhibition in AF players who had sustained concussions during their playing career two decades previously.

Pain relativity in motor control.

Motivational theories of pain highlight its role in people's choices of actions that avoid bodily damage. By contrast, little is known regarding how pain influences action implementation. To explore this less-understood area, we conducted a study in which participants had to rapidly point to a target area to win money while avoiding an overlapping penalty area that would cause pain in their contralateral hand. We found that pain intensity and target-penalty proximity repelled participants' movement away from pain and that motor execution was influenced not by absolute pain magnitudes but by relative pain differences. Our results indicate that the magnitude and probability of pain have a precise role in guiding motor control and that representations of pain that guide action are, at least in part, relative rather than absolute. Additionally, our study shows that the implicit monetary valuation of pain, like many explicit valuations (e.g., patients' use of rating scales in medical contexts), is unstable, a finding that has implications for pain treatment in clinical contexts.

Movement-related potentials in Huntington's disease: movement preparation and execution

Movement-related potentials (MRPs) reflect increasing cortical activity related to the preparation and execution of voluntary movement. Execution and preparatory components may be separated by comparing MRPs recorded from actual and imagined movement. Imagined movement initiates preparatory processes, but not motor execution activity. MRPs are maximal over the supplementary motor area (SMA), an area of the cortex involved in the planning and preparation of movement. The SMA receives input from the basal ganglia, which are affected in Huntington's disease (HD), a hyperkinetic movement disorder. In order to further elucidate the effects of the disorder upon the cortical activity relating to movement, MRPs were recorded from ten HD patients, and ten age-matched controls, whilst they performed and imagined performing a sequential button-pressing task. HD patients produced MRPs of significantly reduced size both for performed and imagined movement. The component relating to movement execution was obtained by subtracting the MRP for imagined movement from the MRP for performed movement, and was found to be normal in HD. The movement preparation component was found by subtracting the MRP found for a control condition of watching the visual cues from the MRP for imagined movement. This preparation component in HD was reduced in early slope, peak amplitude, and post-peak slope. This study therefore reported abnormal MRPs in HD. particularly in terms of the components relating to movement preparation, and this finding may further explain the movement deficits reported in the disease.

A preparação e a execução de tarefa de alcance ao alvo em crianças com transtornos do desenvolvimento da coordenação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The "Quiet Eye" and Motor Performance: Task Demands Matter!

Evidence suggests that superior motor performance coincides with a longer duration of the last fixation before movement initiation, an observation called “quiet eye” (QE). Although the empirical findings over the last two decades underline the robustness of the phenomenon, little is known about its functional role in motor performance. Therefore, a novel paradigm is introduced, testing QE duration as an independent variable by experimentally manipulating the onset of the last fixation before movement unfolding. Furthermore, this paradigm is employed to investigate the functional mechanisms behind the QE phenomenon by manipulating the predictability of the target position and thereby the amount of information to be processed over the QE period. The results further support the assumption that QE affects motor performance, with experimentally prolonged QE durations increasing accuracy in a throwing task. However, it is only under a high information-processing load that a longer QE duration is beneficial for throwing performance. Therefore, the optimization of information processing, particularly in motor execution, turns out to be a promising candidate for explaining QE benefits on a functional level.

Modulation du système glutamatergique pendant l’apprentissage moteur : une étude de spectroscopie par résonance magnétique fonctionnelle

La présente étude avait pour but d’explorer les modulations fonctionnelles putaminales du signal de spectroscopie par résonance magnétique (SRM) combiné du glutamate et de la glutamine (Glx), ainsi que de l’acide γ-aminobutyrique (GABA) en lien avec l’apprentissage d’une séquence motrice. Nous avons émis l’hypothèse que les concentrations de Glx seraient spécifiquement augmentées pendant et après la pratique d’une telle tâche, et ce comparativement à une condition d’exécution motrice simple conçue pour minimiser l’apprentissage. La tâche d’appuis séquentiels des doigts (« finger taping task ») utilisée est connue pour induire un apprentissage moteur évoluant en phases, avec une progression initialement rapide lors de la première session d’entraînement (phase rapide), puis lente lors de sessions subséquentes (phase lente). Cet apprentissage est également conçu comme dépendant de processus « on-line » (pendant la pratique) d’acquisition et « off-line » (entre les périodes de pratique) de consolidation de la trace mnésique de l’habilité motrice. Une grande quantité de données impliquent le système de neurotransmission glutamatergique, principalement par l’action de ses récepteurs N-Méthyl-D-aspartate (NMDAR) et métabotropiques (mGluR), dans une multitude de domaine de la mémoire. Quelques-unes de ces études suggèrent que cette relation s’applique aussi à des mémoires de type motrice ou dépendante du striatum. De plus, certains travaux chez l’animal montrent qu’une hausse des concentrations de glutamate et de glutamine peut être associée à l’acquisition et/ou consolidation d’une trace mnésique. Nos mesures de SRM à 3.0 Tesla, dont la qualité ne s’est avérée satisfaisante que pour le Glx, démontrent qu’une telle modulation des concentrations de Glx est effectivement détectable dans le putamen après la performance d’une tâche motrice. Elles ne nous permettent toutefois pas de dissocier cet effet putativement attribuable à la plasticité du putamen associée à l’apprentissage moteur de séquence, de celui de la simple activation neuronale causée par l’exécution motrice. L’interprétation de l’interaction non significative, montrant une plus grande modulation par la tâche motrice simple, mène cependant à l’hypothèse alternative que la plasticité glutamatergique détectée est potentiellement plus spécifique à la phase lente de l’apprentissage, suggérant qu’une seconde expérience ainsi orientée et utilisant une méthode de SRM plus sensible au Glx aurait donc de meilleures chances d’offrir des résultats concluants.

Desarrollo kinesiológico: la interpretación de un proceso para facilitar el movimiento corporal humano

Este artículo hace una revisión del proceso de producción del movimiento funcional durante el primer año de vida, en un marco kinesiológico, donde se toma el tronco como estabilizador y eje principal en la ejecución motora de las extremidades. La interpretación presentada, facilita el entendimiento de los elementos motores básicos necesarios para construir una actividad más compleja y funcional, lo cual fortalece la habilidad del profesional para observar, evaluar y enfocar su acción en el manejo de personas con discapacidad funcional motora. Esta información es producto de la revisión de la literatura relacionada con el desarrollo normal del movimiento corporal humano y la observación directa del proceso de desarrollo normal y anormal en múltiples niños durante más de 12 años de experiencia profesional. En general, la revisión resalta la interrelación en las actividades de cada segmento corporal con otros y no como elementos aislados, así como la producción de eventos en común desde lo mecánico pero con propósitos diferentes desde lo funcional.

Modulation of event-related desynchronization during kinematic and kinetic hand movements

Background Event-related desynchronization/synchronization (ERD/ERS) is a relative power decrease/increase of electroencephalogram (EEG) in a specific frequency band during physical motor execution and mental motor imagery, thus it is widely used for the brain-computer interface (BCI) purpose. However what the ERD really reflects and its frequency band specific role have not been agreed and are under investigation. Understanding the underlying mechanism which causes a significant ERD would be crucial to improve the reliability of the ERD-based BCI. We systematically investigated the relationship between conditions of actual repetitive hand movements and resulting ERD. Methods Eleven healthy young participants were asked to close/open their right hand repetitively at three different speeds (Hold, 1/3 Hz, and 1 Hz) and four distinct motor loads (0, 2, 10, and 15 kgf). In each condition, participants repeated 20 experimental trials, each of which consisted of rest (8–10 s), preparation (1 s) and task (6 s) periods. Under the Hold condition, participants were instructed to keep clenching their hand (i.e., isometric contraction) during the task period. Throughout the experiment, EEG signals were recorded from left and right motor areas for offline data analysis. We obtained time courses of EEG power spectrum to discuss the modulation of mu and beta-ERD/ERS due to the task conditions. Results We confirmed salient mu-ERD (8–13 Hz) and slightly weak beta-ERD (14–30 Hz) on both hemispheres during repetitive hand grasping movements. According to a 3 × 4 ANOVA (speed × motor load), both mu and beta-ERD during the task period were significantly weakened under the Hold condition, whereas no significant difference in the kinetics levels and interaction effect was observed. Conclusions This study investigates the effect of changes in kinematics and kinetics on resulting ERD during repetitive hand grasping movements. The experimental results suggest that the strength of ERD may reflect the time differentiation of hand postures in motor planning process or the variation of proprioception resulting from hand movements, rather than the motor command generated in the down stream, which recruits a group of motor neurons.

Novel single trial movement classification based on temporal dynamics of EEG

Various complex oscillatory processes are involved in the generation of the motor command. The temporal dynamics of these processes were studied for movement detection from single trial electroencephalogram (EEG). Autocorrelation analysis was performed on the EEG signals to find robust markers of movement detection. The evolution of the autocorrelation function was characterised via the relaxation time of the autocorrelation by exponential curve fitting. It was observed that the decay constant of the exponential curve increased during movement, indicating that the autocorrelation function decays slowly during motor execution. Significant differences were observed between movement and no moment tasks. Additionally, a linear discriminant analysis (LDA) classifier was used to identify movement trials with a peak accuracy of 74%.

Maternal exposure to picrotoxin modifies the response of the GABA(A) receptor during sexual behavior of adult male rat offspring

This study investigated whether perinatal exposure to picrotoxin, a GABA(A) antagonist, modifies the effect of muscimol, a GABA(A) agonist, on the sexual behavior of adult male rats. Two hours after birth and then once daily during the next 9 days of lactation, dams received picrotoxin (0.75 mg/kg subcutaneously) or saline (1 ml/kg subcutaneously). The adult male offspring from the picrotoxin and saline groups received saline (1 ml/kg intraperitoneally) or muscimol (1 mg/kg intraperitoneally), and 15 min later, their sexual behavior was assessed. Muscimol treatment in the saline-exposed group increased the mount and intromission latencies. However, these effects were absent in the picrotoxin-exposed groups. The latencies to first ejaculation, postejaculatory mount, and intromission were decreased in both picrotoxin-exposed groups relative to the saline-exposed groups. The picrotoxin + muscimol-treated rats required more intromissions to ejaculate and the picrotoxin-exposed groups made more ejaculations than the saline-exposed groups. Thus, muscimol treatment did not increase the mount and intromission latencies following picrotoxin exposure, but increased the ejaculation frequency, which did not differ between the picrotoxin + muscimol and the picrotoxin + saline groups. These data indicate that perinatal picrotoxin treatment interfered with GABA(A) receptor development Behavioural Pharmacology 23:703-709 (c) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Brain activation during string playing

This chapter attempts to integrate data from both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) to elucidate the activation of the cortical areas in musical performance for both execution and imagination of music during string playing. In both fMRI and EEG experiments, playing the music was compared with imagining the music. This allowed separation of the areas mainly involved in motor execution from those involved in imagining, planning, and working memory, thus differentiating musical from purely motor areas.

A Thalamic-Fronto-Parietal Structural Covariance Network Emerging in the Course of Recovery from Hand Paresis after Ischemic Stroke.

AIM To describe structural covariance networks of gray matter volume (GMV) change in 28 patients with first-ever stroke to the primary sensorimotor cortices, and to investigate their relationship to hand function recovery and local GMV change. METHODS Tensor-based morphometry maps derived from high-resolution structural images were subject to principal component analyses to identify the networks. We calculated correlations between network expression and local GMV change, sensorimotor hand function and lesion volume. To verify which of the structural covariance networks of GMV change have a significant relationship to hand function, we performed an additional multivariate regression approach. RESULTS Expression of the second network, explaining 9.1% of variance, correlated with GMV increase in the medio-dorsal (md) thalamus and hand motor skill. Patients with positive expression coefficients were distinguished by significantly higher GMV increase of this structure during stroke recovery. Significant nodes of this network were located in md thalamus, dorsolateral prefrontal cortex, and higher order sensorimotor cortices. Parameter of hand function had a unique relationship to the network and depended on an interaction between network expression and lesion volume. Inversely, network expression is limited in patients with large lesion volumes. CONCLUSION Chronic phase of sensorimotor cortical stroke has been characterized by a large scale co-varying structural network in the ipsilesional hemisphere associated specifically with sensorimotor hand skill. Its expression is related to GMV increase of md thalamus, one constituent of the network, and correlated with the cortico-striato-thalamic loop involved in control of motor execution and higher order sensorimotor cortices. A close relation between expression of this network with degree of recovery might indicate reduced compensatory resources in the impaired subgroup.

Non-invasive Detection of Cortical Control Signals for Brain-Computer Interfaces

Thesis (Ph.D.)--University of Washington, 2016-05

Pediatric CNS pathophysiology

Research in pediatric central nervous system pathophysiology is focused around three primary goals: identification of neurodevelopmental disorders, understanding the differences in brain development which underlie these disorders, and improving treatment for these young children. Autism spectrum disorders (ASDs) are a complex set of disorders which are characterized by difficulties in language and social interactions. These behavioral measures are highly variable and a number of underlying causes can generate similar behavioral effects. Therefore, it is important to identify neurophysiological markers to better identify and characterize these disorders. Recent ASD findings using MEG show atypical latency and amplitude responses and poor cortical connectivity in children with ASDs across the cognitive spectrum from basic auditory processing, multisensory integration, to face and semantic processing. These results further support the view that ASDs are a complex neurologically-based disorder. On the other hand, the cause of Down syndrome is well understood as originating from a partial or full replication of chromosome 21. However, the cognitive and neurological consequences of this chromosomal abnormality are not yet well understood. Using a simple observation and motor execution task, poor functional connectivity in sensory-motor areas, particularly in the gamma band range, has been identified in children with Down syndrome and is consistent with behavioral deficits in the sensory-motor realm. Additional studies are needed to better understand whether targeted identification of these abnormalities can facilitate treatment in this disorder. Finally, while epilepsy can be reliably diagnosed, seizure control is still limited in many cases where the seizure onset zone is not readily apparent. Advances in pre-surgical evaluation and intra-operative co-registration will be described. These studies describing pediatric CNS pathophysiology will be discussed. © Springer-Verlag 2010.