Motor Control Processes Research Articles

The effect of Dual-Task modality on midfrontal theta power and driving performance across the adult lifespan

Driving is a complex activity, entailing concurrent preparation and execution of motor behavior, and processing of cognitive information. Dual-tasking often leads to performance decrements, especially when the subtasks require similar neural resources, e.g., controlling the steering wheel, handling the pedals and shifting gears. With higher age, the ability to simultaneously perform different tasks deteriorates, as more mental resources are required for accurate coordination of movements. Therefore, using electroencephalography, we measured the neural correlates of dual-task driving in 81 healthy younger (n = 27), middle-aged (n = 25) and older adults (n = 29). A visuocognitive and a visuomotor dual-task were combined with a simulated lane-keeping task, with the latter dual-task requiring more similar resources. As expected, steering precision decreased to a higher extent when combined with a visuomotor dual-task in all participants, compared to no deterioration in the visuocognitive dual-task. Yet, this visuomotor dual-task performance decrease was more prominent with increasing age. Remarkably, although midfrontal theta power increased in all groups when a visuomotor dual-task was added, indicating the recruitment of additional mental resources, this increase was less prominent for middle-aged and older adults. This could signify a plateau effect of theta power in which a saturation of mental resources is reached, leading to an increased dual-task cost. Therefore, reducing driver task demands by limiting the need for motor control processing, e.g., by switching to automatic gear shifting, could be beneficial for driving safety.

Changes in Resting State Functional Connectivity Associated with Dynamic Adaptation of Wrist Movements.

Dynamic adaptation is an error-driven process of adjusting planned motor actions to changes in task dynamics (Shadmehr, 2017). Adapted motor plans are consolidated into memories that contribute to better performance on re-exposure. Consolidation begins within 15 min following training (Criscimagna-Hemminger and Shadmehr, 2008), and can be measured via changes in resting state functional connectivity (rsFC). For dynamic adaptation, rsFC has not been quantified on this timescale, nor has its relationship to adaptative behavior been established. We used a functional magnetic resonance imaging (fMRI)-compatible robot, the MR-SoftWrist (Erwin et al., 2017), to quantify rsFC specific to dynamic adaptation of wrist movements and subsequent memory formation in a mixed-sex cohort of human participants. We acquired fMRI during a motor execution and a dynamic adaptation task to localize brain networks of interest, and quantified rsFC within these networks in three 10-min windows occurring immediately before and after each task. The next day, we assessed behavioral retention. We used a mixed model of rsFC measured in each time window to identify changes in rsFC with task performance, and linear regression to identify the relationship between rsFC and behavior. Following the dynamic adaptation task, rsFC increased within the cortico-cerebellar network and decreased interhemispherically within the cortical sensorimotor network. Increases within the cortico-cerebellar network were specific to dynamic adaptation, as they were associated with behavioral measures of adaptation and retention, indicating that this network has a functional role in consolidation. Instead, decreases in rsFC within the cortical sensorimotor network were associated with motor control processes independent from adaptation and retention.SIGNIFICANCE STATEMENT Motor memory consolidation processes have been studied via functional magnetic resonance imaging (fMRI) by analyzing changes in resting state functional connectivity (rsFC) occurring more than 30 min after adaptation. However, it is unknown whether consolidation processes are detectable immediately (<15 min) following dynamic adaptation. We used an fMRI-compatible wrist robot to localize brain regions involved in dynamic adaptation in the cortico-thalamic-cerebellar (CTC) and cortical sensorimotor networks and quantified changes in rsFC within each network immediately after adaptation. Different patterns of change in rsFC were observed compared with studies conducted at longer latencies. Increases in rsFC in the cortico-cerebellar network were specific to adaptation and retention, while interhemispheric decreases in the cortical sensorimotor network were associated with alternate motor control processes but not with memory formation.

MICROCEPHALY: A Developmental Disorder

Microcephaly is a result of abnormal in utero development resulting in an unusually small head size. The word comes from a New Latin word, termed as microcephalia, and from two Ancient Greek terminologies that translates into small and head. Back in Ancient Roman times, individuals that were known to carry small heads in comparison to a normal sized human head were all showcased as a public display, whereas people with microcephaly have been occasionally traded to multiple freak shows back in European and North American regions in the nineteenth and twentieth centuries, in which they were regarded as pinheads or freaks of the nature while a lot among them were showcased as a completely different species and were referred to as the lost connection in the evolution process. Growth limitation impacts the Central Nervous System (CNS) and brain in the more serious forms of cases, which might also result in significant perpetual cognitive deficits if the infant manages to survive. Microcephaly is caused by a number of variables, including chromosomal abnormalities as well as other genetic conditions, infections during pregnancy, for instance; rubella, toxoplasmosis, and prenatal exposure to dangerous toxicants.&#x0D; Although drastically deficient cognitive growth is prevalent, problems with motor control processes not showing up until much later in life. Most negatively impacted infants have severe neurological abnormalities and sometimes seizures, as well. Motor function and verbal advancement may also be deferred while hyperactivity and intellectual disability are both prevalent, however to varying degrees. Convulsions are also possible with variations in motor ability; from clumsiness to spastic quadriplegia in some people. The majority of cases of microcephaly are caused by genetic variations. On the one hand, linkage has been discovered between autism, gene duplications, and macrocephaly. On the contrary, a link has been discovered between schizophrenia, gene removals, and microcephaly. Several genotypes, termed as "MCPH" genes, after the gene microcephalin (MCPH1), because of their involvement in cranial capacity and primary microcephaly neuropathies when mutations occur. WDR62 (MCPH2), ASPM (MCPH5), CDK5RAP2 (MCPH3), CENPJ (MCPH6), KNL1 (MCPH4), STIL (MCPH7), CEP152 (MCPH9), ZNF335 (MCPH10), CEP135 (MCPH8), CDK6 (MCPH12), and PHC1 (MCPH11) are among the other genes related to microcephalin gene. Furthermore, a link has been found among repeated genetic variations in recognised genes, including MCPH1 and CDK5RAP2 with structural variations of the brain as examined by Magnetic Resonance Imaging (MRI). The Centres for Disease Control and Prevention and the International Society for Infectious Diseases have linked the expansion of vector-borne Zika virus to an increase in genetically inherited microcephaly. Zika can be transmitted from a pregnant woman to her foetus.&#x0D; Being caused by a reduction in cerebral cortex, and it can occur throughout embryonic and foetal growth phases because of inadequate neural stem cell advancement, impeded neurogenesis, or decrease of neural stem cells. Many genes needed for standard neural development have been discovered through studies in animal models such as rodents. The genes associated with the Notch pathway, for instance, govern stem cell advancement and neurogenesis. Genetic variations induced in mouse models in an experimental setting can induce microcephaly that in comparison is similar to that of the human beings. Abnormal Spindle-like Microcephaly-Associated (ASPM) gene abnormalities have been linked to human microcephaly, and a knockout-model of a ferret with extreme microcephaly has now been designed. Furthermore, viruses like Zika virus and Cytomegalovirus (CMV) have been found to afflict and destroy the brain's primary stem cells and radial glial cells, resulting in the destruction of daughter neurons.&#x0D; A comprehensive physical and history assessments are carried out on patients with microcephaly. Neuroimaging, metabolic evaluation, and genetic examination should be taken into consideration in cases of deteriorating microcephaly. Neuroimaging with Magnetic Resonance Imaging (MRI) is mostly utilized as the very first diagnostic analysis in children suffering from microcephaly. Genetic screening is frequently the very next process after imaging techniques. Microcephaly is a long-term condition with no specific treatment available.

Long-term musical training induces white matter plasticity in emotion and language networks.

Numerous studies have reported that long-term musical training can affect brain functionality and induce structural alterations in the brain. Singing is a form of vocal musical expression with an unparalleled capacity for communicating emotion; however, there has been relatively little research on neuroplasticity at the network level in vocalists (i.e., noninstrumental musicians). Our objective in this study was to elucidate changes in the neural network architecture following long-term training in the musical arts. We employed a framework based on graph theory to depict the connectivity and efficiency of structural networks in the brain, based on diffusion-weighted images obtained from 35 vocalists, 27 pianists, and 33 nonmusicians. Our results revealed that musical training (both voice and piano) could enhance connectivity among emotion-related regions of the brain, such as the amygdala. We also discovered that voice training reshaped the architecture of experience-dependent networks, such as those involved in vocal motor control, sensory feedback, and language processing. It appears that vocal-related changes in areas such as the insula, paracentral lobule, supramarginal gyrus, and putamen are associated with functional segregation, multisensory integration, and enhanced network interconnectivity. These results suggest that long-term musical training can strengthen or prune white matter connectivity networks in an experience-dependent manner.

Cortical Changes as a Result of Sports Injuries: A Short Commentary

Currently, the treatment for the central nervous system (CNS) and neurocognitive fluctuations as a result of sports injuries is considered a relatively uncovered area under the sports neuroscience paradigm. For example, the compensatory neural changes (e.g., brain cortical changes) and the cognitive load can create a feedforward loop that affects recovery and relapse after a musculoskeletal injury. Although several methodologies have been promoted (e.g., brain mapping systems, inhibitory control, and cognitive flexibility), neuromuscular deficits are frequently non-assessed and non-intervened during rehabilitation practices. Here we present an up-to-date description of the most relevant CNS changes after injury, the concept of somatotopic maps, and their relationship with motor control, intracortical inhibition, and cortical facilitation processes. Neuroplasticity strategies beyond the traditional structural-based approaches on the injured tissue are also covered; however, further research is needed to establish evidence-based recommendations for sports professionals.

Auditory and somatosensory feedback mechanisms of laryngeal and articulatory speech motor control.

Speech production is a complex motor task involving multiple subsystems. The relationships between these subsystems need to be comprehensively investigated to understand the underlying mechanisms of speech production. The goal of this paper is to examine the differential contributions of 1) auditory and somatosensory feedback control mechanisms, and 2) laryngeal and articulatory speech production subsystems on speech motor control at an individual speaker level using altered auditory and somatosensory feedback paradigms. Twenty young adults completed speaking tasks in which sudden and unpredictable auditory and physical perturbations were applied to the laryngeal and articulatory speech production subsystems. Auditory perturbations were applied to laryngeal or articulatory acoustic features of speech. Physical perturbations were applied to the larynx and the jaw. Pearson-product moment correlation coefficients were calculated between 1) auditory and somatosensory reflexive responses to investigate relationships between auditory and somatosensory feedback control mechanisms, and 2) laryngeal and articulatory reflexive responses as well as acuity measures to investigate the relationship between auditory-motor features of laryngeal and articulatory subsystems. No statistically significant correlations were found concerning the relationships between auditory and somatosensory feedback. No statistically significant correlations were found between auditory-motor features in the laryngeal and articulatory control subsystems. Results suggest that the laryngeal and articulatory speech production subsystems operate with differential auditory and somatosensory feedback control mechanisms. The outcomes suggest that current models of speech motor control should consider decoupling laryngeal and articulatory domains to better model speech motor control processes.

Multi-modality connectome-based predictive modeling of individualized compulsions in obsessive-compulsive disorder

BackgroundWhile previous neuroimaging studies are mainly focused on dichotomous classification of obsessive-compulsive disorder (OCD) from controls, predicting continuous severity of specific symptom is also pivotal to clinical diagnosis and treatment. MethodsWe applied a machine-learning approach, connectome-based predictive modeling, on functional and structural brain networks constructed from resting-state functional magnetic resonance imaging and diffusion tensor imaging data to decode compulsions and obsessions of fifty-four patients with OCD. ResultsWe successfully predicted individualized compulsions with a positive model of structural brain network and with a negative model of functional brain network. The structural predictive brain network comprises the motor cortex, cerebellum and limbic lobe, which are involved in basic motor control, motor execution and emotion processing, respectively. The functional predictive brain network is composed by the prefrontal and limbic systems which are related to cognitive and affective control. Computational lesion analysis shows that functional connectivity among the salience network (SN), the frontal parietal network and the default mode network, as well as structural connectivity within the SN are vital in the individualized prediction of compulsions in OCD. LimitationsThere was no external validation of large samples to test the robustness of our predictive model. ConclusionsThese findings provide the first evidence for the predictive role of the triple network model in individualized compulsions and have important implications in diagnosis, prognosis and treatment of patients with OCD.

Microstructural alterations predict impaired bimanual control in Parkinson's disease.

Bimanual coordination is impaired in Parkinson’s disease affecting patients’ ability to perform activities of daily living and to maintain independence. Conveyance of information between cortical and subcortical areas is essential for bimanual coordination and relies on the integrity of cerebral microstructure. As pathological deposition of alpha-synuclein compromises microstructure in Parkinson’s disease, we investigated the relationship between microstructural integrity and bimanual coordination using diffusion-weighted MRI in 23 patients with Parkinson’s disease (mean age ± standard deviation: 56.0 ± 6.45 years; 8 female) and 26 older adults (mean age ± standard deviation: 58.5 ± 5.52 years). Whole-brain analysis revealed specific microstructural alterations between patients and healthy controls matched for age, sex, handedness, and cognitive status congruent with the literature and known Parkinson’s disease pathology. A general linear model revealed distinct microstructural alterations associated with poor bimanual coordination in Parkinson’s disease, corrected for multiple comparisons using a permutation-based approach. Integrating known functional topography, we conclude that distinct changes in microstructure cause an impediment of structures involved in attention, working memory, executive function, motor planning, motor control, and visual processing contributing to impaired bimanual coordination in Parkinson’s disease.

The Absence of Caspase-8 in the Dopaminergic System Leads to Mild Autism-like Behavior.

In the last decade, new non-apoptotic roles have been ascribed to apoptotic caspases. This family of proteins plays an important role in the sculpting of the brain in the early stages of development by eliminating excessive and nonfunctional synapses and extra cells. Consequently, impairments in this process can underlie many neurological and mental illnesses. This view is particularly relevant to dopamine because it plays a pleiotropic role in motor control, motivation, and reward processing. In this study, we analyze the effects of the elimination of caspase-8 (CASP8) on the development of catecholaminergic neurons using neurochemical, ultrastructural, and behavioral tests. To do this, we selectively delete the CASP8 gene in cells that express tyrosine hydroxylase with the help of recombination through the Cre-loxP system. Our results show that the number of dopaminergic neurons increases in the substantia nigra. In the striatum, the basal extracellular level of dopamine and potassium-evoked dopamine release decreased significantly in mice lacking CASP8, clearly showing the low dopamine functioning in tissues innervated by this neurotransmitter. This view is supported by electron microscopy analysis of striatal synapses. Interestingly, behavioral analysis demonstrates that mice lacking CASP8 show changes reminiscent of autism spectrum disorders (ASD). Our research reactivates the possible role of dopamine transmission in the pathogenesis of ASD and provides a mild model of autism.

Hemodynamic responses of quiet standing simultaneously performed with different cognitive loads in older adults.

Postural control decrements with advancing age have been largely identified in the literature. Dual-task paradigms have been utilized to increase older adults' stability in order to direct the attention towards the completion of a secondary task, leaving the automatic motor control processes to modulate posture unconstrained. To the extent that older adults allocate greater attentional resources to maintain an upright posture, the present study aimed at replicating St-Amant et al. (2020) protocol to investigate automatic postural control and prefrontal cortex activation in older adults when simultaneously performing quiet standing wtih different attention-demanding cognitive tasks. Nineteen healthy older adults (71.47±6.01years) were recruited and self-reported no hearing, musculoskeletal and neurological problems. Older adults were required to perform three different cognitive loads while seated (SC), quietly standing on a force platform (SM), and performing both tasks simultaneously (DT). Static center-of-pressure measurements and wavelet discrete transform did not reveal postural automaticity in dual-task conditions. Conversely, sample entropy values were significantly greater when performing n-back compared to all other tasks in the medial-lateral direction, and significantly greater than SM in the anterior-posterior direction. The relative concentration of oxygenated hemoglobin (HbO) of the left hemisphere was significantly greater than the right when performing n-back, and significantly greater within the left hemisphere when performing n-back compared to double-number sequence. Collectively, our results do not support the presence of automatic postural control in dual-task conditions for older adults. The present study highlights the importance of using numerous variables when investigating posture in order to capture its complexity.

Shared mechanisms underlie mental imagery and motor planning

Many studies have associated mental imagery with motor control mechanisms by showing mutually active brain areas and functions, as well as similar temporal patterns of imagining and executing the same motor actions. One of the main conjectured mutual mechanisms is the Cerebellar forward-model, commonly believed to generate sensory predictions as part of both motor control and mental imagery processes. Nevertheless, trials to associate one’s overall individual mental and motor capacities have shown only mild and inconsistent correlations, hence challenging the mutual mechanism assumption. We hypothesized that one cause to this inconsistency is the forward-model’s dominance in the motor-planning stage only when adapting to novel sensorimotor environments, while the inverse-model is gradually taking the lead along the adaptation, and therefore biasing most attempts to measure motor-mental overlapping functions and correlate these measurements under regular circumstances. Our current study aimed to tackle and explore this gap using immersive virtual embodiment, by applying an experience of a fundamental sensorimotor conflict, thereby manipulating the sensory prediction mechanism, and presumably forcing an increased involvement of the forward-model in the motor planning stage throughout the experiment. In the study, two groups of subjects (n = 48) performed mental and manual rotation within an immersive, motion-captured, virtual reality environment, while the sensorimotor dynamics of only the test group were altered by physical-virtual speed re-mapping making the virtual hand move twice as fast as the physical hand controlling it. Individual mental imagery capacities were assessed before and after three blocks of manual-rotation, where motor planning durations were measured as the time until motion onset. The results show that virtual sensorimotor alteration extremely increases the correlation of mental imagery and motor planning (r = 0.9, p < .0001) and leads to higher mental imagery performance improvement following the physical blocks. We particularly show that virtual embodiment manipulation affects the motor planning stage to change and functionally overlap with imagery mechanisms, rather than the other way around, which supports our conjecture of an increased sensory-prediction forward-model involvement. Our results shed new light on the embodied nature of mental imagery, support the view of the predictive forward-model as a key mechanism mutually underlying motor control and imagery, and suggest virtual sensorimotor alteration as a novel methodology to increase physical-mental convergence. These findings also suggest the applicability of using existing motion-tracked virtual environments for continuous cognitive evaluation and treatment, through kinematic analysis of ongoing natural motor behaviors.

Factors governing the assignment of visual consequence to the corresponding action.

To achieve fast feedback control of voluntary movements, the visual consequences of our motor commands need to be quickly identified and analyzed by the motor control processes in the brain. These processes work remarkably well even in complex visual environments and in the face of discrepancies between physical actuator and visually perceived effect, e.g. when moving a computer mouse on a visually crowded screen. Here, we use an ambiguous situation in which a single cursor could be controlled by either the left or the right hand to determine the visual and cognitive factors that determine the assignment of a visual stimulus to the corresponding motor command. Our results demonstrate that the visuomotor system is exquisitely sensitive to the spatio-temporal correlation between cursor and hands, learning the appropriate mapping implicitly within several minutes. In contrast, spatial proximity between end effector and visual consequence has an immediate but only transient effect on the assignment process. Finally, an explicit instruction about which hand controls the cursor only has a minor influence when the instruction is presented first. These findings provide insight into the relative importance of the factors that determine the binding of visual information to the corresponding motor structures to enable fast feedback control.NEW & NOTEWORTHY For efficient visuomotor online control, the brain needs to solve the correspondence problem between an ongoing movement and its visual consequences. Here, we challenge the visuomotor system with an ambiguous reaching task, in which the visual feedback was controlled by either hand or by a combination of both. Our findings characterize the properties of a flexible assignment process that quickly takes into account the spatio-temporal properties of movements and the visual scene.

Nonlinear refinement of functional brain connectivity in golf players of different skill levels

Different functional connectivities in the brain, specifically in the frontoparietal and motor cortex–sensorimotor circuits, have been associated with superior performance in athletes. However, previous electroencephalogram (EEG) studies have only focused on the frontoparietal circuit and have not provided a comprehensive understanding of the cognitive–motor processes underlying superior performance. We used EEG coherence analysis to examine the motor cortex–sensorimotor circuit in golfers of different skill levels. Twenty experts, 18 amateurs, and 21 novices performed 60 putts at individual putting distances (40–60% success rate). The imaginary inter-site phase coherence (imISPC) was used to compute 8–13 Hz coherence that can be used to distinguish expert-novice and expert-amateur differences during motor preparation. We assessed the 8–13 Hz imISPC between the Cz and F3, F4, C3, C4, T3, T4, P3, P4, O1, and O2 regions. (1) Amateurs had lower 8–13 Hz imISPC in the central regions (Cz–C3 and C4) than novices and experts, but experts had lower 8–13 Hz imISPC than novices. (2) Skilled golfers (experts and amateurs) had lower 8–13 Hz imISPC in the central–parietal regions (Cz–P3 and P4) than novices. (3) Experts had lower 8–13 Hz imISPC in the central–left temporal regions (Cz–T7) than amateurs and novices. Our study revealed that refinement of the motor cortex–sensorimotor circuit follows a U-shaped coherence pattern based on the stage of learning. The early learning stage (i.e., novice to amateur) is characterized by lower connectivity between the regions associated with motor control and visuospatial processes, whereas the late learning stage (i.e., amateur to expert) is characterized by lower connectivity in the regions associated with verbal-analytic and motor control processes.

Embedded Machine Learning Using a Multi-Thread Algorithm on a Raspberry Pi Platform to Improve Prosthetic Hand Performance.

High accuracy and a real-time system are priorities in the development of a prosthetic hand. This study aimed to develop and evaluate a real-time embedded time-domain feature extraction and machine learning on a system on chip (SoC) Raspberry platform using a multi-thread algorithm to operate a prosthetic hand device. The contribution of this study is that the implementation of the multi-thread in the pattern recognition improves the accuracy and decreases the computation time in the SoC. In this study, ten healthy volunteers were involved. The EMG signal was collected by using two dry electrodes placed on the wrist flexor and wrist extensor muscles. To reduce the complexity, four time-domain features were applied to extract the EMG signal. Furthermore, these features were used as the input of the machine learning. The machine learning evaluated in this study were k-nearest neighbor (k-NN), Naive Bayes (NB), decision tree (DT), and support vector machine (SVM). In the SoC implementation, the data acquisition, feature extraction, machine learning, and motor control process were implemented using a multi-thread algorithm. After the evaluation, the result showed that the pairing of the MAV feature and machine learning DT resulted in higher accuracy among other combinations (98.41%) with a computation time of ~1 ms. The implementation of the multi-thread algorithm in the pattern recognition system resulted in significant impact on the time processing.

Linking Pain and Motor Control: Conceptualization of Movement Deficits in Patients With Painful Conditions.

This Perspective proposes that approaching PRMD from a contemporary motor control perspective will uncover key mechanisms, identify treatment targets, inform assessments, and innovate treatments across sensory-perceptual, cognitive, and motor domains, all of which have the potential to improve movement and functional outcomes in patients with painful conditions.

Time for Action: Neural Basis of the Costs and Benefits of Temporal Predictability for Competing Response Choices.

The brain can anticipate the time of imminent events to optimize sensorimotor processing. Yet, there can be behavioral costs of temporal predictability under situations of response conflict. Here, we sought to identify the neural basis of these costs and benefits by examining motor control processes in a combined EEG-EMG study. We recorded electrophysiological markers of response activation and inhibition over motor cortex when the onset-time of visual targets could be predicted, or not, and when responses necessitated conflict resolution, or not. If stimuli were temporally predictable but evoked conflicting responses, we observed increased intertrial consistency in the delta range over the motor cortex involved in response implementation, perhaps reflecting increased response difficulty. More importantly, temporal predictability differentially modulated motor cortex activity as a function of response conflict before the response was even initiated. This effect occurred in the hemisphere ipsilateral to the response, which is involved in inhibiting unwanted actions. If target features all triggered the same response, temporal predictability increased cortical inhibition of the incorrect response hand. Conversely, if different target features triggered two conflicting responses, temporal predictability decreased inhibition of the incorrect, yet prepotent, response. This dissociation reconciles the well-established behavioral benefits of temporal predictability for nonconflicting responses as well as its costs for conflicting ones by providing an elegant mechanism that operates selectively over the motor cortex involved in suppressing inappropriate actions just before response initiation. Taken together, our results demonstrate that temporal information differentially guides motor activity depending on response choice complexity.

P.0288 Resting-state functional connectivity in male perpetrators is associated with motor control process

P.0288 Resting-state functional connectivity in male perpetrators is associated with motor control process

Brain Processes Involved in Motor Planning Are a Dominant Factor for Inducing Event-Related Desynchronization.

Event-related desynchronization (ERD) is a relative attenuation in the spectral power of an electroencephalogram (EEG) observed over the sensorimotor area during motor execution and motor imagery. It is a well-known EEG feature and is commonly employed in brain-computer interfaces. However, its underlying neural mechanisms are not fully understood, as ERD is a single variable correlated with external events involving numerous pathways, such as motor intention, planning, and execution. In this study, we aimed to identify a dominant factor for inducing ERD. Participants were instructed to grasp their right hand with three different (10, 25, or 40%MVF: maximum voluntary force) levels under two distinct experimental conditions: a closed-loop condition involving real-time visual force feedback (VF) or an open-loop condition in a feedforward (FF) manner. In each condition, participants were instructed to repeat the grasping task a certain number of times with a timeline of Rest (10.0 s), Preparation (1.0 s), and Motor Execution (4.0 s) periods, respectively. EEG signals were recorded simultaneously with the motor task to evaluate the time-course of the event-related spectrum perturbation for each condition and dissect the modulation of EEG power. We performed statistical analysis of mu and beta-ERD under the instructed grasping force levels and the feedback conditions. In the FF condition (i.e., no force feedback), mu and beta-ERD were significantly attenuated in the contralateral motor cortex during the middle of the motor execution period, while ERD in the VF condition was maintained even during keep grasping. Only mu-ERD at the somatosensory cortex tended to be slightly stronger in high load conditions. The results suggest that the extent of ERD reflects neural activity involved in the motor planning process for changing virtual equilibrium point rather than the motor control process for recruiting motor neurons to regulate grasping force.

Exploring the Relationship Between Speech Motor Control and Phonological Processing in Children Who Stutter and Typically Developed Children

Introduction: Language processing (especially phonology) and speech motor control are disordered in stuttering. However, it is unclear how they are related based on the models of speech processing. The present study aimed to study non-word repetition, rhyme and alliteration judgment, and speech motor control and investigate their relationship in children who stutter (CWS) compared to typically developed children (TDC). Materials and Methods: Twenty-eight CWS (mean age=5.46 years) and 28 peers TDC (mean age=5.52 years) participated in this study. Phonological processing, according to the speech processing model, is divided into phonological input and output. Phonological input, phonological output, and speech motor control were assessed by rhyme and alliteration tasks, accurate phonological production during non-word repetition task, and Robbins-Klee oral speech motor protocol, respectively. The Pearson correlation coefficient, independent t-test, and Cohen’s d were used for data analysis. Results: Both non-word repetition and speech motor skills were significantly different in CWS than TDC (P&lt;0.001). But rhyme and alliteration judgment were similar across groups (P&gt;0.001). Phonological processing and speech motor control were not significantly correlated (P&gt;0.001). Conclusion: Phonological processing (output), a level before articulation, and speech motor control are not correlated, but both are disordered in preschool CWS. Additionally, phonological processing (input) is similar in CWS and TDC. That is, phonological input is not affected by stuttering in CWS.

Neuronal Oscillatory Signatures of Joint Attention and Intersubjectivity in Arrhythmic Coaction.

Hyper-brain studies analyze the brain activity of two or more individuals during some form of interaction. Several studies found signs of inter-subject brain activity coordination, such as power and phase synchronization or information flow. This hyper-brain coordination is frequently studied in paradigms which induce rhythms or even synchronization, e.g., by mirroring movements, turn-based activity in card or economic games, or joint music making. It is therefore interesting to figure out in how far coordinated brain activity may be induced by a rhythmicity in the task and/or the sensory feedback that the partners receive. We therefore studied the EEG brain activity of dyads in a task that required the smooth pursuit of a target and did not involve any extrinsic rhythms. Partners controlled orthogonal axes of the two-dimensional motion of an object that had to be kept on the target. Using several methods for analyzing hyper-brain coupling, we could not detect signs of coordinated brain activity. However, we found several brain regions in which the frequency-specific activity significantly correlated with the objective task performance, the subjective experience thereof, and of the collaboration. Activity in these regions has been linked to motor control, sensorimotor integration, executive control and emotional processing. Our results suggest that neural correlates of intersubjectivity encompass large parts of brain areas that are considered to be involved in sensorimotor control without necessarily coordinating their activity across agents.