Higher Motor Control Research Articles

Motor Control Alterations and the Perception of Postural Instability in non-Fallers Latinx-Hispanic Adults Living with HIV

People who have advanced HIV can display inadequate postural control because of the virus affecting the brain. Antiretroviral therapy (ART) mitigates some repercussions of the disease, maintaining a healthy immune system. The issue is that prolonged usage of ART may affect balance at a slower pace. Purpose: Assess postural control and balance perception in Latinx-Hispanic people living with HIV with a stable immune system. Methods: 42 (30 men and 12women) subjects took part in the investigation (57.2± 8.7 years old). Participants had to be diagnosed with HIV to enroll in the study with a CD4 count of > 500 cells/µL. The eight balance tasks (15 s each) were accomplished on a thick balance foam mat and further partitioned into two parts, four single and four dual cognitive tasks (subjects counting backward three numbers at a time). Results: We measured balance using body-worn accelerometers (ACC) and the ABC scale. There was a considerable increase in sway movements within the different tasks, χ2 (8) = 194.314, p = 0.00. This increment in postural movements was observed when single and dual tasks were contrasted for EO (Z=-2.169, p=005) and EOHUD (Z=-2.344, p 0.05). Related to the ABC scale, subjects scored lower, notably in tasks involving more balance demands. Conclusion: HIV-diagnosed individuals with a stable immune system exhibit increased postural alteration and perceive balance difficulties with activities requiring higher motor control demands. Clinicians should assess the balance in people living with HIV in all stages of the disease as a prevention tool.

Parent-report Of Children’s Motor Skills Are Selectively Related To Interference Control Among School-aged Children

PURPOSE: Previous research has demonstrated that aerobic fitness and adiposity impact children’s cognitive function. However, whether children’s motor skills independently impact childhood cognition remains unclear. This study examined relationships between children’s motor skills and executive function, relational memory, and academic achievement among school-aged children without diagnosed coordination disorder. METHODS: Participants were children ages 7-12 years old (N=90 [46 females]). Intellectual abilities and academic achievement were measured using the Woodcock-Johnson IV Test (WCJ). Selective attention was assessed using a Flanker task, and relational memory was assessed using a spatial reconstruction task. Aerobic fitness and whole-body adiposity (%Fat) were assessed using a VO2max test and DXA, respectively. Parents completed the Developmental Coordination Disorder Questionnaire (DCDQ) as an assessment of the child’s current motor skill abilities. Spearman and partial spearman correlation tests were conducted to explore potential relationships. RESULTS: 14% of participants indicated a possible developmental coordination disorder and 50% had a score of 67 and above on the DCDQ. Covariates adjusted for included sex, IQ, socioeconomic status (SES), fitness, and %Fat. Following adjustment, higher scores on the control during movement subscale of the DCDQ were related to greater performance in story recall (Rho= 0.29; P=0.039), a subscale of the WCJ. There was no significant relationship between relational memory and any of the DCDQ outcomes. However, higher scores on the control during movement subscale were related to lower accuracy interference during the Flanker task (Rho=-0.25; P=0.03), indicating that children who had higher motor control while moving exhibited greater selective attention, compared to those who had poorer control abilities during movement. CONCLUSION: Motor control abilities were associated with recall memory and attentional abilities in school-aged children, independent of aerobic fitness and adiposity. Funding: This work was funded by the University of Illinois and the Egg Nutrition Center.

Stereotyped, automatized and habitual behaviours: are they similar constructs under the control of the same cerebral areas?

Comprehensive knowledge about higher executive functions of motor control has been covered in the last decades. Critical goals have been targeted through many different technological approaches. An abundant flow of new results greatly progressed our ability to respond at better-posited answers to look more than ever at the challenging neural system functioning. Behaviour is the observable result of the invisible, as complex cerebral functioning. Many pathological states are approached after symptomatology categorisation of behavioural impairments is achieved. Motor, non-motor and psychiatric signs are greatly shared by many neurological/psychiatric disorders. Together with the cerebral cortex, the basal ganglia contribute to the expression of behaviour promoting the correct action schemas and the selection of appropriate sub-goals based on the evaluation of action outcomes. The present review focus on the basic classification of higher motor control functioning, taking into account the recent advances in basal ganglia structural knowledge and the computational model of basal ganglia functioning. We discuss about the basal ganglia capability in executing ordered motor patterns in which any single movement is linked to each other into an action, and many actions are ordered into each other, giving them a syntactic value to the final behaviour. The stereotypic, automatized and habitual behaviour's constructs and controls are the expression of successive stages of rule internalization and categorisation aimed in producing the perfect spatial-temporal control of motor command.

EP 1. Brain activity after acute left hemispheric stroke in imitation and tool associated actions

Background Apraxia, a disorder of higher motor control, frequently leads to impaired tool use or imitation capacities due to left hemispheric lesions. However, despite similar lesion size or location, patients present with different apraxic deficits thus different early reorganization mechanism may be assumed. To understand the impaired praxis network after stroke on a functional level, we correlated behavioral performance in imitation and tool use tasks with activation patterns in fMRI of 47 acute left-hemispheric stroke patients. Methods A cohort of 47 acute stroke patients (mean age 63.5 years ± SD 13.6; 13 female) with first ever embolic stroke in the left arteria cerebri media territory were tested for deficits in imitation of meaningless hand and finger postures and tool associated actions (pantomime of tool use, imitation of tool use, actual tool use). Testing was performed mean 4.8 days ± SD 2.9 post stroke. FMRI was acquired during presentation of video sequences of tool-associated actions viewed from a first-person perspective. Voxel wise linear regression analyses for task scores only and with lesion volume as covariate as well as group differences for categorized behavioral performance (deficit vs. no deficit) were calculated to analyze activity associated with behavioral performance in tool use and meaningless imitation. Analyses were performed using GLMflex. Results are presented on a p Results Intact imitation of meaningless postures was associated with activation in the left middle occipital gyrus as well as in the left superior temporal lobe in linear regression analyses and categorical group differences (deficit vs. no deficit). Tool associated tasks correlated with activation in the left supramarginal gyrus and superior temporal lobe without occipital activation. For group differences in pantomime of tool use (deficit vs. no deficit) an additional activation for patients with low behavioral performance could be found in the posterior middle temporal gyrus. Conclusion For intact imitation of meaningless postures and tool associated actions, specific left hemispheric activation patterns in the acute phase after stroke could be determined. These areas are commonly associated to the left hemispheric praxis network. While intact imitation of meaningless gestures seems to rely on intact left middle occipital gyrus for visual analysis of the presented movement tool associated actions rather seem to rely on integrity of the supramarginal gyrus, known to store movement engrams. Patients with deficits in pantomime of tool use additionally show activation of posterior middle temporal gyrus for semantic movement information. These mechanisms possibly can be interpreted as early compensatory effort.

Supplementary Motor Complex and Disturbed Motor Control - a Retrospective Clinical and Lesion Analysis of Patients after Anterior Cerebral Artery Stroke.

Both the supplementary motor complex (SMC), consisting of the supplementary motor area (SMA) proper, the pre-SMA, and the supplementary eye field, and the rostral cingulate cortex are supplied by the anterior cerebral artery (ACA) and are involved in higher motor control. The Bereitschaftspotential (BP) originates from the SMC and reflects cognitive preparation processes before volitional movements. ACA strokes may lead to impaired motor control in the absence of limb weakness and evoke an alien hand syndrome (AHS) in its extreme form. To characterize the clinical spectrum of disturbed motor control after ACA strokes, including signs attributable to AHS and to identify the underlying neuroanatomical correlates. A clinical assessment focusing on signs of disturbed motor control including intermanual conflict (i.e., bilateral hand movements directed at opposite purposes), lack of self-initiated movements, exaggerated grasping, motor perseverations, mirror movements, and gait apraxia was performed. Symptoms were grouped into (A) AHS-specific and (B) non-AHS-specific signs of upper limbs, and (C) gait apraxia. Lesion summation mapping was applied to the patients' MRI or CT scans to reveal associated lesion patterns. The BP was recorded in two patients. Ten patients with ACA strokes (nine unilateral, one bilateral; mean age: 74.2 years; median NIH-SS at admission: 13.0) were included in this case series. In the acute stage, all cases had marked difficulties to perform volitional hand movements, while movements in response to external stimuli were preserved. In the chronic stage (median follow-up: 83.5 days) initiation of voluntary movements improved, although all patients showed persistent signs of disturbed motor control. Impaired motor control is predominantly associated with damaged voxels within the SMC and the anterior and medial cingulate cortex, while lesions within the pre-SMA are specifically related to AHS. No BP was detected over the damaged hemisphere. ACA strokes involving the premotor cortices, particularly the pre-SMA, are associated with AHS-specific signs. In the acute phase, motor behavior is characterized by the inability to carry out self-initiated movements. Motor control deficits may persist to a variable degree beyond the acute phase. Alterations of the BP point to an underlying SMC dysfunction in AHS.

P101. Impact of aging on motor control networks underlying movement selection and initiation

Introduction Healthy elderly adults typically show greater regional activity in frontoparietal brain regions relative to young adults when performing motor control tasks ( Ward and Frackowiak, 2003 , Vallesi et al., 2011 ). However, the functional role of enhanced activity within the motor network is still a matter of debate. One hypothesis is that higher levels of neural activity reflect a compensatory mechanism to account for age-related decline in neural networks. We, therefore, used a systems-level approach to investigate networks dynamics underlying motor control in young and elderly subjects. We hypothesized that advanced aging is associated with reduced connectivity in the basic motor network, which is compensated by stronger influence of non-primary motor areas like prefrontal cortex. Methods We scanned 12 young (age 22–33) and 12 elderly subjects (age 52–74) employing a computerized task involving both basic (finger tapping) and higher motor control processing (internally and externally cued movement selection and initiation). Dynamic Causal Modelling (DCM) for fMRI was used to assess effective connectivity in a bilateral frontoparietal network comprising dorsolateral prefrontal cortex, dorsal premotor cortex, intraparietal cortex and primary motor cortex. Results Elderly subjects showed a significant slowing in movement selection and initiation. This slowing was accompanied by increases in both regional brain activity and effective connectivity between frontoparietal brain regions in elderly compared to young subjects. However, within the group of elderly subjects, coupling strengths of premotor cortex with primary motor cortex and intraparietal cortex decreased with advancing age, whereas connectivity between prefrontal and premotor cortex increased as a function of age. Discussion Network interactions underlying visuomotor transformation (parietal-premotor) and motor execution (premotor-primary motor cortex) follow an U-curve relationship: Connectivity is generally elevated in old relative to young subjects, yet decreases with advanced aging. In contrast, prefrontal influences on premotor cortex increase with advanced aging. These findings are in line with the ”posterior to anterior shift theory” described for regional brain activity, thereby extending it to network interactions related to higher motor control ( Davis et al., 2008 ).

Dopaminergic modulation of motor network dynamics in Parkinson's disease.

Although characteristic motor symptoms of Parkinson's disease such as bradykinesia typically improve under dopaminergic medication, deficits in higher motor control are less responsive. We here investigated the dopaminergic modulation of network dynamics underlying basic motor performance, i.e. finger tapping, and higher motor control, i.e. internally and externally cued movement preparation and selection. Twelve patients, assessed ON and OFF medication, and 12 age-matched healthy subjects underwent functional magnetic resonance imaging. Dynamic causal modelling was used to assess effective connectivity in a motor network comprising cortical and subcortical regions. In particular, we investigated whether impairments in basic and higher motor control, and the effects induced by dopaminergic treatment are due to connectivity changes in (i) the mesial premotor loop comprising the supplementary motor area; (ii) the lateral premotor loop comprising lateral premotor cortex; and (iii) cortico-subcortical interactions. At the behavioural level, we observed a marked slowing of movement preparation and selection when patients were internally as opposed to externally cued. Preserved performance during external cueing was associated with enhanced connectivity between prefrontal cortex and lateral premotor cortex OFF medication, compatible with a context-dependent compensatory role of the lateral premotor loop in the hypodopaminergic state. Dopaminergic medication significantly improved finger tapping speed in patients, which correlated with a drug-induced coupling increase of prefrontal cortex with the supplementary motor area, i.e. the mesial premotor loop. In addition, only in the finger tapping condition, patients ON medication showed enhanced excitatory influences exerted by cortical premotor regions and the thalamus upon the putamen. In conclusion, the amelioration of bradykinesia by dopaminergic medication seems to be driven by enhanced connectivity within the mesial premotor loop and cortico-striatal interactions. In contrast, medication did not improve internal motor control deficits concurrent to missing effects at the connectivity level. This differential effect of dopaminergic medication on the network dynamics underlying motor control provides new insights into the clinical finding that in Parkinson's disease dopaminergic drugs especially impact on bradykinesia but less on executive functions.

Avaliação do torque passivo de flexão plantar e torque ativo de flexão dorsal em ginastas rítmicas e não atletas

O treinamento realizado por atletas de elite acarreta demandas funcionais específicas que produzem mudanças nos tendões e nas propriedades musculares. Nas atletas de ginástica rítmica (GR) há uma exigência maior de controle motor em posições extremas de flexão plantar. Esta demanda pode alterar o torque passivo dos flexores plantares bem como influenciar na amplitude de movimento (ADM) de flexão dorsal e torque dos dorsiflexores. No presente estudo foi comparada a ADM de flexão dorsal de GR e meninas não atletas (MNA), e determinada a correlação entre o torque passivo dos flexores plantares (TPFP) e o torque ativo dos flexores dorsais (TAFD). O estudo incluiu 10 GR e 10 MNA. A ADM de flexão dorsal foi medida com um goniômetro. O TPFP e TAFD foram avaliados por meio de um dinamômetro isocinético em cinco ângulos articulares (20º, 10º, 0º, -10º e -20º). O teste T para amostras independentes foi utilizado para a comparação entre os grupos (α = 0,05). O coeficiente de correlação de Pearson indicou uma correlação negativa alta e moderada entre o TPFP e TAFD para as GR e NA, respectivamente. GR apresentaram menor ADM de flexão dorsal comparadas às MNA. O TPFP foi significativamente maior nas GR comparado as MNA. Por outro lado, o TAFD foi maior nas MNA. A correlação do TPFP com o TAFD foi de r = -0,82; p < 0,01 e r = -0,68; p < 0,01 para GR e MNA, respectivamente. Os resultados sugerem que a alta demanda mecânica nos flexores plantares na GR aumenta o TPFP que pode influenciar negativamente na ADM dos flexores dorsais e no TAFD.

An age-related shift of resting-state functional connectivity of the subthalamic nucleus: a potential mechanism for compensating motor performance decline in older adults.

Healthy aging is associated with decline in basic motor functioning and higher motor control. Here, we investigated age-related differences in the brain-wide functional connectivity (FC) pattern of the subthalamic nucleus (STN), which plays an important role in motor response control. As earlier studies revealed functional coupling between STN and basal ganglia, which both are known to influence the conservativeness of motor responses on a superordinate level, we tested the hypothesis that STN FC with the striatum becomes dysbalanced with age. To this end, we performed a seed-based resting-state analysis of fMRI data from 361 healthy adults (mean age: 41.8, age range: 18–85) using bilateral STN as the seed region of interest. Age was included as a covariate to identify regions showing age-related changes of FC with the STN seed. The analysis revealed positive FC of the STN with several previously described subcortical and cortical regions like the anterior cingulate and sensorimotor cortex, as well as not-yet reported regions including central and posterior insula. With increasing age, we observed reduced positive FC with caudate nucleus, thalamus, and insula as well as increased positive FC with sensorimotor cortex and putamen. Furthermore, an age-related reduction of negative FC was found with precuneus and posterior cingulate cortex. We suggest that this reduced de-coupling of brain areas involved in self-relevant but motor-unrelated cognitive processing (i.e. precuneus and posterior cingulate cortex) from the STN motor network may represent a potential mechanism behind the age-dependent decline in motor performance. At the same time, older adults appear to compensate for this decline by releasing superordinate motor control areas, in particular caudate nucleus and insula, from STN interference while increasing STN-mediated response control over lower level motor areas like sensorimotor cortex and putamen.

Partitioning age-related changes in brain activation using a virtual performance task to simulate complex movements

Event Abstract Back to Event Partitioning age-related changes in brain activation using a virtual performance task to simulate complex movements Toshiharu Nakai1*, Ayuko Tanaka1, Mitsunobu Kunimi1, Sachiko Kiyama1 and Yoshiaki Shiraishi2 1 National Center for Geriatrics and Gerontology, Neuroimaging & Informatics, Japan 2 Nagoya Institute of Technology Graduate School of Engineering, Computer Science and Engineering, Japan Aging has become a serious social issue, especially in Asian countries. In order to maintain the activities of elderly people, social programs to promote physical and mental exercises are conducted. Although some investigations have reported that those activities potentially contribute to the prevention of cognitive decline [1], the neurological background has not been systematically verified. We investigated the availability of a virtual performance task designed from such exercises as a model to test age-related changes in brain function [2]. An event-related fMRI task representing the motor behavior in the bean transfer test (BTT), which is used as one component of the test battery to evaluate the physical ability of elderly in Japan, was designed. The task consisted of two operations using a 2 by 2 turnkey system. With the left-hand key, a small, round object (bean) is pinched with two lines representing chopsticks. Then, the object with chopsticks is moved to a round target (pot) with the right-hand key to put the bean in. The behavioral data were marked with 6 checkpoints (Fig.1). The onset of each trial was determined using the sum of two jittering factors, the execution time for each trial by the subject and periodically altering the interval time before the onset of each trial. fMRI data were obtained using the EPI sequence on a 3T MR scanner, and the data sets were analyzed using SPM8. fMRI data were obtained from 11 elderly (over 60, 6 females) and 7 non-elderly (under 54) volunteers. In the activation representing the total trial, the network for the upper visuo-spatial transformation tract and higher motor control was observed in the elderly (two-sample t-test, p<0.05). Differential peaks between the two age groups were detected as augmented activation in the left BA5 ([-23 -38 59]) and bilateral BA6 ([-60 -2 47], [60 2 38]) in the elderly group (Fig.2, CPall). In the partitioned maps, it was indicated that this difference was mostly contributed to by the first task switching point (CP2) and pinching the object (CP1). Activation of these areas was not significant in the CP3 and CP4 map in the elderly. On the other hand, activation was augmented in the dorsal visuo-motor pathway in the young subjects during these steps. It was suggested that these results represent: 1) a higher demand for visuo-spatial transformation by adjusting the asymmetric (two independent) rotation of the sticks, and 2) a lower frequency of object transference to the goal than pinching it in elderly subjects. By recording self-paced object manipulation in the interactive task, complex brain activation during a combined motor processing could be more precisely attributed to cognitive elements. This feature was useful to further partitioning age-related changes in brain activation. Figure 1 Figure 2 Acknowledgements This research was supported by a Grant-in-Aid for Scientific Research (KAKENHI) # 21300196 and 24300186 supported by MEXT.

Polymodal conceptual processing of human biological actions in the left inferior frontal lobe

Apart from being increasingly implicated in higher motor control, Broca's area is considered to play an important role in action understanding by coding the motor goal of an action. Moreover, recent findings suggest that parts of Broca's area may be able to code action content in a more abstract fashion, independent of modality, specific movement parameters or effector used. We performed functional magnetic resonance imaging to examine whether in humans processing object-directed hand actions presented either visually as video clips or verbally as spoken sentences relies on the same neural substrates. To control for action specificity, we included videos and sentences depicting inanimate motion events. In order to induce conceptual processing, we asked participants to make judgements about the acceptability of the stimuli. Results show that processing object-directed hand actions presented both visually and verbally leads to common activation of areas in parietal and frontal regions, most prominently in the pars opercularis of Broca's region. We conclude that the pars opercularis of Broca's area is endowed with polymodal capabilities, allowing the processing of higher-level conceptual aspects of action understanding.

Multiple-dipole analysis of visual event-related potentials during oddball paradigms

Visual event-related potentials (ERPs) during oddball paradigms with button pressing, silent counting and movement imagery tasks were recorded in right-handed subjects from 32 scalp electrodes. By incorporating the knowledge deduced from the task relevance of the P300 into equivalent current dipole source localization (ECDL), stable multiple ECD solutions with goodness-of-fit (GOF) of more than 90% and confidence limits (CLs) of less than 1 mm were estimated for all the three target P300s. The obtained frontal dipoles were discussed in terms of visual working memory, sustained attention and higher motor control in reference to the previous PET, fMRI and MEG studies. The distributed multiple ECDs may suggest that P300 should be interpreted as being the embodiment of the cortico-limbic-thalamic network accomplishing various cognitive functions.

Theories for Skilled Limb Movements .

Some of the theories that have been advanced to perform skilled limb movements are reviewed in this paper. The aspects discussed in brief include alpha-gamma control, choice of control variables in limb movements, equilibrium point hypotheses, experimental observations from simple movement studies and explanations proposed, in particular the dual strategy hypothesis. The single mechanical degree-of-freedom movements may be controlled by one of two strategies: a speed-insensitive strategy or a speed-sensitive strategy. The term strategy implies a set of rules which specify in terms of task variables and subject instructions how to choose the excitation signal, the controlling signal at the alpha motoneuron level. The two strategies differ in that speed-insensitive strategy is a result of duration modulation of the excitation pulse, whereas the speed-sensitive strategy is a result from amplitude modulation. Finally, the problem of multi-degrees of freedom movements and the role of higher motor control centres are discussed in brief.

THE VERTICAL LOBE AND TOUCH LEARNING IN THE OCTOPUS.

ABSTRACT The vertical lobe is the topmost part of the brain of a cephalopod. It is the largest of a series of lobes, characterized by small cells and a dense neuropil, overlying parts of the supraoesophageal brain concerned with higher motor control. Because of its position it is easy to remove surgically.