Ifft, Peter J; Shokur, Solaiman; Li, Zheng; Lebedev, Mikhail A; Nicolelis, Miguel A L
Brain-machine interfaces (BMIs) are artificial systems that aim to restore sensation and movement to paralyzed patients. So far, BMIs have enabled only one arm to be moved at a time. Control of bimanual arm movements remains a major challenge. We have developed and tested a bimanual BMI that enables rhesus monkeys to control two avatar arms simultaneously. The bimanual BMI was based on the extracellular activity of 374 to 497 neurons recorded from several frontal and parietal cortical areas of both cerebral hemispheres. Cortical activity was transformed into movements of the two arms with a decoding algorithm called a fifth-order unscented Kalman filter (UKF). The UKF was trained either during a manual task performed with two joysticks or by having the monkeys passively observe the movements of avatar arms. Most cortical neurons changed their modulation patterns when both arms were engaged simultaneously. Representing the two arms jointly in a single UKF decoder resulted in improved decoding performance compared with using separate decoders for each arm. As the animals' performance in bimanual BMI control improved over time, we observed widespread plasticity in frontal and parietal cortical areas. Neuronal representation of the avatar and reach targets was enhanced with learning, whereas pairwise correlations between neurons initially increased and then decreased. These results suggest that cortical networks may assimilate the two avatar arms through BMI control. These findings should help in the design of more sophisticated BMIs capable of enabling bimanual motor control in human patients.
Zaal, Frank T. J. M.; Bongers, Raoul M.
The classic understanding of prehension is that of coordinated reaching and grasping. An alternative view is that the grasping in prehension emerges from independently controlled individual digit movements (the double-pointing model). The current study tested this latter model in bimanual prehension
Macaluso, Emiliano; Cherubini, Andrea; Sabatini, Umberto
The aim of this study was to investigate intra-regional activation and inter-regional connectivity during passive movement. During fMRI, a mechanic device was used to move the subject's index and middle fingers. We assessed four movement conditions (unimanual left/right, bimanual symmetric/asymmetric), plus Rest. A conventional intra-regional analysis identified the passive stimulation network, including motor cortex, primary and secondary somatosensory cortex, plus the cerebellum. The posterior (sensory) part of the sensory-motor activation around the central sulcus showed a significant modulation according to the symmetry of the bimanual movement, with greater activation for asymmetric compared to symmetric movements. A second set of fMRI analyses assessed condition-dependent changes of coupling between sensory-motor regions around the superior central sulcus and the rest of the brain. These analyses showed a high inter-regional covariation within the entire network activated by passive movement. However, the specific experimental conditions modulated these patterns of connectivity. Highest coupling was observed during the Rest condition, and the coupling between homologous sensory-motor regions around the left and right central sulcus was higher in bimanual than unimanual conditions. These findings demonstrate that passive movement can affect the connectivity within the sensory-motor network. We conclude that implicit detection of asymmetry during bimanual movement relies on associative somatosensory region in post-central areas, and that passive stimulation reduces the functional connectivity within the passive movement network. Our findings open the possibility to combine passive movement and inter-regional connectivity as a tool to investigate the functionality of the sensory-motor system in patients with very poor mobility.
Full Text Available The aim of this study was to investigate intra-regional activation and inter-regional connectivity during passive movement. During fMRI, a mechanic device was used to move the subject's index and middle fingers. We assessed four movement conditions (unimanual left/right, bimanual symmetric/asymmetric, plus Rest. A conventional intra-regional analysis identified the passive stimulation network, including motor cortex, primary and secondary somatosensory cortex, plus the cerebellum. The posterior (sensory part of the sensory-motor activation around the central sulcus showed a significant modulation according to the symmetry of the bimanual movement, with greater activation for asymmetric compared to symmetric movements. A second set of fMRI analyses assessed condition-dependent changes of coupling between sensory-motor regions around the superior central sulcus and the rest of the brain. These analyses showed a high inter-regional covariation within the entire network activated by passive movement. However, the specific experimental conditions modulated these patterns of connectivity. Highest coupling was observed during the Rest condition, and the coupling between homologous sensory-motor regions around the left and right central sulcus was higher in bimanual than unimanual conditions. These findings demonstrate that passive movement can affect the connectivity within the sensory-motor network. We conclude that implicit detection of asymmetry during bimanual movement relies on associative somatosensory region in post-central areas, and that passive stimulation reduces the functional connectivity within the passive movement network. Our findings open the possibility to combine passive movement and inter-regional connectivity as a tool to investigate the functionality of the sensory-motor system in patients with very poor mobility.
Gallivan, Jason P.
Abstract During goal-directed reaching, rapid visuomotor feedback processes enable the human motor system to quickly correct for errors in the trajectory of the hand that arise from motor noise and, in some cases, external perturbations. To date, these visuomotor responses, the gain of which is sensitive to features of the task and environment, have primarily been examined in the context of unimanual reaching movements toward a single target. However, many natural tasks involve moving both hands together, often to separate targets, such that errors can occur in parallel and at different spatial locations. Here, we examined the resource capacity of automatic visuomotor corrective mechanisms by comparing feedback gains during bimanual reaches, toward two targets, to feedback gains during unimanual reaches toward single targets. To investigate the sensitivity of the feedback gains and their relation to visual-spatial processing, we manipulated the widths of the targets and participants’ gaze location. We found that the gain of corrective responses to cursor displacements, while strongly modulated by target width and gaze position, were only slightly reduced during bimanual control. Our results show that automatic visuomotor corrective mechanisms can efficiently operate in parallel across multiple spatial locations.
Takiyama, Ken; Sakai, Yutaka
Certain theoretical frameworks have successfully explained motor learning in either unimanual or bimanual movements. However, no single theoretical framework can comprehensively explain motor learning in both types of movement because the relationship between these two types of movement remains unclear. Although our recent model of a balanced motor primitive framework attempted to simultaneously explain motor learning in unimanual and bimanual movements, this model focused only on a limited subset of bimanual movements and therefore did not elucidate the relationships between unimanual movements and various bimanual movements. Here, we extend the balanced motor primitive framework to simultaneously explain motor learning in unimanual and various bimanual movements as well as the transfer of learning effects between unimanual and various bimanual movements; these phenomena can be simultaneously explained if the mean activity of each primitive for various unimanual movements is balanced with the corresponding mean activity for various bimanual movements. Using this balanced condition, we can reproduce the results of prior behavioral and neurophysiological experiments. Furthermore, we demonstrate that the balanced condition can be implemented in a simple neural network model.
Frank T J M Zaal
Full Text Available The classic understanding of prehension is that of coordinated reaching and grasping. An alternative view is that the grasping in prehension emerges from independently controlled individual digit movements (the double-pointing model. The current study tested this latter model in bimanual prehension: participants had to grasp an object between their two index fingers. Right after the start of the movement, the future end position of one of the digits was perturbed. The perturbations resulted in expected changes in the kinematics of the perturbed digit but also in adjusted kinematics in the unperturbed digit. The latter effects showed up when the end position of the right index finger was perturbed, but not when the end position of the left index finger was perturbed. Because the absence of a coupling between the digits is the core assumption of the double-pointing model, finding any perturbation effects challenges this account of prehension; the double-pointing model predicts that the unperturbed digit would be unaffected by the perturbation. The authors conclude that the movement of the digits in prehension is coupled into a grasping component.
Full Text Available Stroke patients recover more effectively when they are rehabilitated with bimanual movement rather than with unimanual movement; however, it remains unclear why bimanual movement is more effective for stroke recovery. Using a computational model of stroke recovery, this study suggests that bimanual movement facilitates the reorganization of a damaged motor cortex because this movement induces rotations in the preferred directions (PDs of motor cortex neurons. Although the tuning curves of these neurons differ during unimanual and bimanual movement, changes in PD, but not changes in modulation depth, facilitate such reorganization. In addition, this reorganization was facilitated only when encoding PDs are rotated, but decoding PDs are not rotated. Bimanual movement facilitates reorganization because this movement changes neural activities through inter-hemispheric inhibition without changing cortical-spinal-muscle connections. Furthermore, stronger inter-hemispheric inhibition between motor cortices results in more effective reorganization. Thus, this study suggests that bimanual movement is effective for stroke rehabilitation because this movement rotates the encoding PDs of motor cortex neurons.
Rudisch, J.; Butler, J.; Izadi, H.; Zielinski, I.M.; Aarts, P.B.M.; Birtles, D.; Green, D.
Children with unilateral Cerebral Palsy (uCP) experience problems performing tasks requiring the coordinated use of both hands (bimanual coordination; BC). Additionally, some children with uCP display involuntary symmetrical activation of the opposing hand (mirrored movements). Measures, used to inv
Full Text Available When we learn a bimanual motor skill (e.g., rowing a boat, we often break it down into unimanual practices (e.g., a rowing drill with the left or right arm. Such unimanual practice is thought to be useful for learning bimanual motor skills efficiently because the learner can concentrate on learning to perform a simpler component. However, it is not so straightforward to assume that unimanual training improves bimanual performance. We have previously demonstrated that motor memories for reaching movements consist of 3 different parts: unimanual-specific, bimanual-specific, and overlapping parts. According to this scheme, unimanual training appears to be less effective, as its training effect is only partially transferred to the same limb for bimanual movement. In the present study, counter-intuitively, we demonstrate that, even after the bimanual skill is almost fully learned by means of bimanual training, additional unimanual training could further improve bimanual skill. We hypothesized that this effect occurs because unimanual training increases the memory content in the overlapping part, which might contribute to an increase in the memory for bimanual movement. To test this hypothesis, we examined whether the unimanual training performed after sufficient bimanual training could improve the bimanual performance. Participants practiced performing bimanual reaching movements in the presence of a novel force-field imposed only on their left arm. As an index for the motor performance, we used the error-clamp method (i.e., after-effect of the left arm to evaluate the force output to compensate for the force-field during the reaching movement. After sufficient bimanual training, the training effect reached a plateau. However, unimanual training performed subsequently improved the bimanual performance significantly. In contrast, when the same amount of bimanual training was continued, the bimanual performance remained unchanged, highlighting the
Yan, Li-Rong; Wu, Yi-Bo; Zeng, Xiao-Hua; Gao, Li-Chen
Parkinson's disease (PD) is a neurodegenerative disorder affecting middle-aged and elderly people. PD can be viewed as "circuit disorder," indicating that large scale cortico-subcortical pathways were involved in its pathophysiology. The brain network in an experimental context is emerging as an important biomarker in disease diagnosis and prognosis prediction. This context-dependent network for PD and the underling functional mechanism remains unclear. In this paper, the brain network profiles in 11 PD patients without dementia were studied and compared with 12 healthy controls. The functional magnetic resonance imaging (fMRI) data were acquired when the subjects were performing a pseudorandomized unimanual or bimanual finger-to-thumb movement task. The activation was detected and the network profiles were analyzed by psychophysiological interaction (PPI) toolbox. For the controls and PD patients, the motor areas including the primary motor and premotor areas, supplementary motor area, the cerebellum and parts of the frontal, temporal and parietal gyrus were activated. The right putamen exhibited significant control > PD activation and weaker activity during the bimanual movement relative to the unimanual movement in the control group. The decreased putamen modulation on some nucleus in basal ganglia, such as putamen, thalamus and caudate, and some cortical areas, such as cingulate, parietal, angular, frontal, temporal and occipital gyrus was detected in the bimanual movement condition relative to the unimanual movement condition. Between-group PPI difference was detected in cingulate gyrus, angular gyrus and precuneus (control > PD) and inferior frontal gyrus (PD > control). The deficient putamen activation and its enhanced connectivity with the frontal gyrus could be a correlate of impaired basal ganglia inhibition and frontal gyrus compensation to maintain the task performance during the motor programs of PD patients.
Winston D Byblow
Full Text Available Repetitive mirror symmetric bilateral upper limb may be a suitable priming technique for upper limb rehabilitation after stroke. Here we demonstrate neurophysiological and behavioural after-effects in healthy participants after priming with 20 minutes of repetitive active-passive bimanual wrist flexion and extension in a mirror symmetric pattern with respect to the body midline (MIR compared to an control priming condition with alternating flexion-extension (ALT. Transcranial magnetic stimulation (TMS indicated that corticomotor excitability (CME of the passive hemisphere remained elevated compared to baseline for at least 30 minutes after MIR but not ALT, evidenced by an increase in the size of motor evoked potentials in ECR and FCR. Short and long-latency intracortical inhibition (SICI, LICI, short afferent inhibition (SAI and interhemispheric inhibition (IHI were also examined using pairs of stimuli. LICI differed between patterns, with less LICI after MIR compared with ALT, and an effect of pattern on IHI, with reduced IHI in passive FCR 15 minutes after MIR compared with ALT and baseline. There was no effect of pattern on SAI or FCR H-reflex. Similarly, SICI remained unchanged after 20 minutes of MIR. We then had participants complete a timed manual dexterity motor learning task with the passive hand during, immediately after, and 24 hours after MIR or control priming. The rate of task completion was faster with MIR priming compared to control conditions. Finally, ECR and FCR MEPs were examined within a pre-movement facilitation paradigm of wrist extension before and after MIR. ECR, but not FCR, MEPs were consistently facilitated before and after MIR, demonstrating no degradation of selective muscle activation. In summary, mirror symmetric active-passive bimanual movement increases CME and can enhance motor learning without degradation of muscle selectivity. These findings rationalise the use of mirror symmetric bimanual movement as a
Gelkop, Nava; Burshtein, Dikla Gol; Lahav, Anat; Brezner, Amichi; Al-Oraibi, Saleh; Ferre, Claudio L; Gordon, Andrew M
We examined the efficacy of modified constraint-induced movement therapy (CIMT) and hand-arm bimanual intensive therapy (HABIT) in a special education preschool/kindergarten in Israel. Twelve children (1.5-7 years) with congenital hemiplegic cerebral palsy were randomized to receive modified CIMT (n = 6) or HABIT (n = 6). Occupational and physical therapists administered usual and customary care for 8 weeks; children then crossed over to receive CIMT or HABIT 2 hr/day, 6 days/week for 8 weeks from their occupational therapist. The Assisting Hand Assessment and Quality of Upper Extremity Skills Test were administered 2 months prior to the intervention, immediately before, immediately after intervention, and 6 months after the first baseline assessment. Both groups demonstrated no change during baseline and comparable improvement following CIMT and HABIT (p < .001), which was maintained at 6-month follow-up. Results suggest that modified CIMT and HABIT provided in school-based settings can lead to improvements in quality of bimanual skill and movement patterns.
Burns, Martin K.; Patel, Vrajeshri; Florescu, Ionut; Pochiraju, Kishore V.; Vinjamuri, Ramana
Kinematic and neuromuscular synergies have been found in numerous aspects of human motion. This study aims to determine how effectively kinematic synergies in bilateral upper arm movements can be used to replicate complex activities of daily living (ADL) tasks using a sparse optimization algorithm. Ten right-handed subjects executed 18 rapid and 11 natural-paced ADL tasks requiring bimanual coordination while sitting at a table. A position tracking system was used to track the subjects’ arms in space, and angular velocities over time for shoulder abduction, shoulder flexion, shoulder internal rotation, and elbow flexion for each arm were computed. Principal component analysis (PCA) was used to generate kinematic synergies from the rapid-paced task set for each subject. The first three synergies accounted for 80.3 ± 3.8% of variance, while the first eight accounted for 94.8 ± 0.85%. The first and second synergies appeared to encode symmetric reaching motions which were highly correlated across subjects. The first three synergies were correlated between left and right arms within subjects, whereas synergies four through eight were not, indicating asymmetries between left and right arms in only the higher order synergies. The synergies were then used to reconstruct each natural-paced task using the l1-norm minimization algorithm. Temporal dilations of the synergies were introduced in order to model the temporal scaling of movement patterns achieved by the cerebellum and basal ganglia as reported previously in the literature. Reconstruction error was reduced by introducing synergy dilations, and cumulative recruitment of several synergies was significantly reduced in the first 10% of training task time by introducing temporal dilations. The outcomes of this work could open new scenarios for the applications of postural synergies to the control of robotic systems, with potential applications in rehabilitation. These synergies not only help in providing near
Li, Yong; Levin, Oron; Forner-Cordero, Arturo; Ronsse, Renaud; Swinnen, Stephan P
The present study examined the principles underlying inter and intralimb coordination constraints during performance of bimanual elbow-wrist movements at different cycling frequencies (from 0.75 Hz to 2.50 Hz). Participants performed eight coordination tasks that consisted of a combination of in-phase (IN) and/or anti-phase (AN) coordination modes between both elbows and wrists (interlimb), with isodirectional (Iso) or non-isodirectional (NonI) coordination modes within each limb (intralimb). As expected, the principle of muscle homology (in-phase coordination), giving rise to mirror symmetrical movements with respect to the mid-sagittal plane, had a powerful influence on the quality of global coordinative behavior both between and within limbs. When this principle was violated (i.e., when the anti-phase mode was introduced in one or both joint pairs), the non-isodirectional intralimb mode exhibited a (de)stabilizing role in coordination, which became more pronounced at higher cycling frequencies. However, pattern loss with increasing cycling frequency resulted not only in convergence toward the more stable in-phase patterns with the elbows and wrists but also to the anti-phase patterns (which were associated with directional compatibility of within-limb motions). Moreover, participants generally preserved their initial mode of coordination (either in-phase or anti-phase) in the proximal joints (i.e., elbows) while shifting from anti-phase to in-phase (or vice versa) with their distal joint pair (i.e., wrists). Taken together, these findings reflect the impact of two immanent types of symmetry in bimanual coordination: mirror-image and translational symmetry.
Sallard, Etienne; Spierer, Lucas; Ludwig, Catherine; Deiber, Marie-Pierre; Barral, Jérôme
Deficits in the processing of sensory reafferences have been suggested as accounting for age-related decline in motor coordination. Whether sensory reafferences are accurately processed can be assessed based on the bimanual advantage in tapping: because of tapping with an additional hand increases kinesthetic reafferences, bimanual tapping is characterized by a reduced inter-tap interval variability than unimanual tapping. A suppression of the bimanual advantage would thus indicate a deficit in sensory reafference. We tested whether elderly indeed show a reduced bimanual advantage by measuring unimanual (UM) and bimanual (BM) self-paced tapping performance in groups of young (n = 29) and old (n = 27) healthy adults. Electroencephalogram was recorded to assess the underlying patterns of oscillatory activity, a neurophysiological mechanism advanced to support the integration of sensory reafferences. Behaviorally, there was a significant interaction between the factors tapping condition and age group at the level of the inter-tap interval variability, driven by a lower variability in BM than UM tapping in the young, but not in the elderly group. This result indicates that in self-paced tapping, the bimanual advantage is absent in elderly. Electrophysiological results revealed an interaction between tapping condition and age group on low beta band (14-20 Hz) activity. Beta activity varied depending on the tapping condition in the elderly but not in the young group. Source estimations localized this effect within left superior parietal and left occipital areas. We interpret our results in terms of engagement of different mechanisms in the elderly depending on the tapping mode: a 'kinesthetic' mechanism for UM and a 'visual imagery' mechanism for BM tapping movement.
Full Text Available Abstract Background Congenital hemiplegia is the most common form of cerebral palsy (CP accounting for 1 in 1300 live births. These children have limitations in capacity to use the impaired upper limb and bimanual coordination deficits which impact on daily activities and participation in home, school and community life. There are currently two diverse intensive therapy approaches. Traditional therapy has adopted a bimanual approach (BIM training and recently, constraint induced movement therapy (CIMT has emerged as a promising unimanual approach. Uncertainty remains about the efficacy of these interventions and characteristics of best responders. This study aims to compare the efficacy of CIMT to BIM training to improve outcomes across the ICF for school children with congenital hemiplegia. Methods/Design A matched pairs randomised comparison design will be used with children matched by age, gender, side of hemiplegia and level of upper limb function. Based on power calculations a sample size of 52 children (26 matched pairs will be recruited. Children will be randomised within pairs to receive either CIMT or BIM training. Both interventions will use an intensive activity based day camp model, with groups receiving the same dosage of intervention delivered in the same environment (total 60 hours over 10 days. A novel circus theme will be used to enhance motivation. Groups will be compared at baseline, then at 3, 26 and 52 weeks following intervention. Severity of congenital hemiplegia will be classified according to brain structure (MRI and white matter fibre tracking, cortical excitability using Transcranial Magnetic Stimulation (TMS, functional use of the hand in everyday tasks (Manual Ability Classification System and Gross Motor Function Classification System (GMFCS. Outcomes will address neurovascular changes (functional MRI, functional connectivity, and brain (reorganisation (TMS, body structure and function (range of motion, spasticity
Massen, Cristina; Sattler, Christine
Research on bimanual coordination of hand movements has identified several loci of bimanual interference, including interference because of programming different movement parameters or selecting different targets for the two hands. This study investigates the extent and origin of interference when participants execute bimanual actions with tools.…
Modified constraint-induced movement therapy or bimanual occupational therapy following injection of Botulinum toxin-A to improve bimanual performance in young children with hemiplegic cerebral palsy: a randomised controlled trial methods paper
Full Text Available Abstract Background Use of Botulinum toxin-A (BoNT-A for treatment of upper limb spasticity in children with cerebral palsy has become routine clinical practice in many paediatric treatment centres worldwide. There is now high-level evidence that upper limb BoNT-A injection, in combination with occupational therapy, improves outcomes in children with cerebral palsy at both the body function/structure and activity level domains of the International Classification of Functioning, Disability and Health. Investigation is now required to establish what amount and specific type of occupational therapy will further enhance functional outcomes and prolong the beneficial effects of BoNT-A. Methods/Design A randomised, controlled, evaluator blinded, prospective parallel-group trial. Eligible participants were children aged 18 months to 6 years, diagnosed with spastic hemiplegic cerebral palsy and who were able to demonstrate selective motor control of the affected upper limb. Both groups received upper limb injections of BoNT-A. Children were randomised to either the modified constraint-induced movement therapy group (experimental or bimanual occupational therapy group (control. Outcome assessments were undertaken at pre-injection and 1, 3 and 6 months following injection of BoNT-A. The primary outcome measure was the Assisting Hand Assessment. Secondary outcomes included: the Quality of Upper Extremity Skills Test; Pediatric Evaluation of Disability Inventory; Canadian Occupational Performance Measure; Goal Attainment Scaling; Pediatric Motor Activity Log; modified Ashworth Scale and; the modified Tardieu Scale. Discussion The aim of this paper is to describe the methodology of a randomised controlled trial comparing the effects of modified constraint-induced movement therapy (a uni-manual therapy versus bimanual occupational therapy (a bimanual therapy on improving bimanual upper limb performance of children with hemiplegic cerebral palsy following
Sacrey, Lori-Ann R; Karl, Jenni M; Whishaw, Ian Q
The reach-to-eat movement, transport of a hand to grasp an object that is withdrawn and placed in the mouth, is amongst the earliest developing functional movements of human infants. The present longitudinal study is the first description of the maturation of hand-rotation, hand shaping, and accuracy associated with the advance and withdrawal phases of the movement. Eight infants, aged 6-12 months, and eight adults, were video recorded as they reached for familiar objects or food items. Hand, arm, and trunk movements were assessed frame-by-frame with the Skilled Reaching Rating Scale, previously developed for the assessment of adult reaching, and supplementary kinematic analysis. Reach-to-eat maturation was characterized by three changes. First, for advance, a simple open hand transport gradually matured to a movement associated with pronation and hand shaping of the digits for precision grasping. Second, for withdrawal to the mouth, a direct withdrawal movement gradually became associated with hand supination that oriented the target object to the mouth. Third, associated with the maturation of rotational movements, inaccurate and fragmented hand transport and withdrawal movements developed into precise targeting of the hand-to-object and object-to-mouth. Across the age range, there was a decrease in bimanual reaching and an increase in right handed reaching. The results are discussed in relation to the idea that the maturation of the reach-to-eat movement involves the development of rotational and shaping movements of the hand and visual and somatosensory guidance of a preferred hand.
Janet H Bultitude
Full Text Available It has been suggested that incongruence between signals for motor intention and sensory input can cause pain and other sensory abnormalities. This claim is supported by reports that moving in an environment of induced sensorimotor conflict leads to elevated pain and sensory symptoms in those with certain painful conditions. Similar procedures can lead to reports of anomalous sensations in healthy volunteers too. In the present study, we used mirror visual feedback to investigate the effects of sensorimotor incongruence on responses to stimuli that arise from sources external to the body, in particular, touch. Incongruence between the sensory and motor signals for the right arm was manipulated by having the participants make symmetrical or asymmetrical movements while watching a reflection of their left arm in a parasagittal mirror, or the left hand surface of a similarly positioned opaque board. In contrast to our prediction, sensitivity to the presence of gaps in tactile stimulation of the right forearm was not reduced when participants made asymmetrical movements during mirror visual feedback, as compared to when they made symmetrical or asymmetrical movements with no visual feedback. Instead, sensitivity was reduced when participants made symmetrical movements during mirror visual feedback relative to the other three conditions. We suggest that small discrepancies between sensory and motor information, as they occur during mirror visual feedback with symmetrical movements, can impair tactile processing. In contrast, asymmetrical movements with mirror visual feedback may not impact tactile processing because the larger discrepancies between sensory and motor information may prevent the integration of these sources of information. These results contrast with previous reports of anomalous sensations during exposure to both low and high sensorimotor conflict, but are nevertheless in agreement with a forward model interpretation of perceptual
Full Text Available Controlling the movement of the arm to achieve a goal, such as reaching for an object, is challenging because it requires coordinating many muscles acting on many joints. The central nervous system might simplify the control of reaching by directly mapping initial states and goals into muscle activations through the combination of muscle synergies, coordinated recruitment of groups of muscles with specific activation profiles. Here we review recent results from the analysis of reaching muscle patterns supporting such a control strategy. Muscle patterns for point-to-point movements can be reconstructed by the combination of a small number of time-varying muscle synergies, modulated in amplitude and timing according to movement directions and speeds. Moreover, the modulation and superposition of the synergies identified from point-to-point movements captures the muscle patterns underlying multi-phasic movements, such as reaching through a via-point or to a target whose location changes after movement initiation. Thus, the sequencing of time-varying muscle synergies might implement an intermittent controller which would allow the construction of complex movements from simple building blocks.
Aarts, P.B.M.; Jongerius, P.H.; Geerdink, Y.A.; Limbeek, J. van; Geurts, A.C.H.
A recent randomized controlled trial indicated that modified Constraint-Induced Movement Therapy followed by Bimanual Training (mCIMT-BiT) is an effective intervention to improve spontaneous use of the affected upper limb in children with unilateral spastic cerebral palsy (CP). The present study aim
Aarts, Pauline B.; Jongerius, Peter H.; Geerdink, Yvonne A.; van Limbeek, Jacques; Geurts, Alexander C.
A recent randomized controlled trial indicated that modified Constraint-Induced Movement Therapy followed by Bimanual Training (mCIMT-BiT) is an effective intervention to improve spontaneous use of the affected upper limb in children with unilateral spastic cerebral palsy (CP). The present study aimed to investigate how the above-mentioned…
The Pirate group intervention protocol: description and a case report of a modified constraint-induced movement therapy combined with bimanual training for young children with unilateral spastic cerebral palsy.
Aarts, P.B.M.; Hartingsveldt, M. van; Anderson, P.G.; Tillaar, I. van den; Burg, J. van der; Geurts, A.C.H.
The purpose of this article was to describe a child-friendly modified constraint-induced movement therapy protocol that is combined with goal-directed task-specific bimanual training (mCIMT-BiT). This detailed description elucidates the approach and supports various research reports. This protocol i
Kuehn, Esther; De Havas, Jack; Silkoset, Emilie; Gomi, Hiroaki; Haggard, Patrick
Proprioception can be defined as the sense for body movement and position. While most sensory information can be successfully integrated across hemispheres, little is known about the bilateral integration of proprioceptive information. In two behavioural experiments, we investigated whether estimates of the position of one hand are influenced by simultaneous proprioceptive information from the other hand. We further investigated whether such putative bimanual proprioceptive integration would differ between expert dancers and non-dancer controls. Either one hand or both hands were passively moved to novel positions, and participants indicated the perceived location of the index finger tip of the designated target hand, by orienting a visible laser beam mounted on a cap. Synchronized bimanual movements compared to unimanual movements significantly improved proprioceptive position sense. In particular, we found a bias reduction to perceive the target hand's index finger tip as shifted away from the midline in the bimanual condition, compared to the unimanual condition. Expert dancers, in contrast, did not show this change in proprioceptive position sense after bimanual movements. We suggest that bimanual movements may improve proprioception due to interhemispheric integration in controls, but not in expert dancers.
Effects of modified constraint-induced movement therapy and functional bimanual training on upper extremity function and daily activities in a patient with incomplete spinal cord injury: a case study.
Kim, Yeon-Ju; Kim, Jin-Kyung; Park, So-Yeon
[Purpose] In this study, we examined effects of modified constraint-induced movement therapy (m-CIMT) and functional bimanual training, when applied to a patient with incomplete spinal cord injury, on upper extremity function and daily activities. [Subject and Methods] One patient, diagnosed with C4 incomplete spinal cord injury, underwent physical therapy with constraint-induced movement therapy for 3 hours and task-oriented bimanual training for 1 hour, per day. This combined 4-hour session was performed five times a week, for 3 weeks, totaling 15 sessions. Upper extremity function was measured using the Manual Function Test (MFT) and Box & Block Test (BBT). Additionally, Spinal Cord Independence Measure Version III (SCIM-III) and Short Form 36 Health Survey (SF-36) were used to assess functional outcomes. [Results] Mobility of the hand and overall function of upper extremities were enhanced following intervention. Moreover, the subject's quality of life and ability to carry out daily activities also improved. [Conclusion] Modified constraint-induced movement therapy and bimanual training was effective in enhancing upper extremity function and performance of daily routines in a patient with incomplete spinal cord injury. Further studies, recruiting multiple subjects, should focus on m-CIMT using diverse methods, performed during the course of daily activities.
Gladstone, Marshall; And Others
To test for interhemispheric difficulties associated with dyslexia, this study assessed bimanual coordination in dyslexic and nondisabled boys using an Etch-a-Sketch-like task. Dyslexics showed significant impairments on mirror movements, and often unknowingly reverted to parallel movements when visual feedback was removed. (RH)
Goble, Daniel J; Coxon, James P; Van Impe, Annouchka; De Vos, Jeroen; Wenderoth, Nicole; Swinnen, Stephan P
Coordinated hand use is an essential component of many activities of daily living. Although previous studies have demonstrated age-related behavioral deficits in bimanual tasks, studies that assessed the neural basis underlying such declines in function do not exist. In this fMRI study, 16 old and 16 young healthy adults performed bimanual movements varying in coordination complexity (i.e., in-phase, antiphase) and movement frequency (i.e., 45, 60, 75, 90% of critical antiphase speed) demands. Difficulty was normalized on an individual subject basis leading to group performances (measured by phase accuracy/stability) that were matched for young and old subjects. Despite lower overall movement frequency, the old group "overactivated" brain areas compared with the young adults. These regions included the supplementary motor area, higher order feedback processing areas, and regions typically ascribed to cognitive functions (e.g., inferior parietal cortex/dorsolateral prefrontal cortex). Further, age-related increases in activity in the supplementary motor area and left secondary somatosensory cortex showed positive correlations with coordinative ability in the more complex antiphase task, suggesting a compensation mechanism. Lastly, for both old and young subjects, similar modulation of neural activity was seen with increased movement frequency. Overall, these findings demonstrate for the first time that bimanual movements require greater neural resources for old adults in order to match the level of performance seen in younger subjects. Nevertheless, this increase in neural activity does not preclude frequency-induced neural modulations as a function of increased task demand in the elderly.
Foerster, Rebecca M; Carbone, Elena; Koesling, Hendrik; Schneider, Werner X
Principles of saccadic eye movement control in the real world have been derived by the study of self-paced well-known tasks such as sandwich or tea making. Little is known whether these principles generalize to high-speed sensorimotor tasks and how they are affected by learning and automatization. In the present study, right-handers practiced the speed-stacking task in 14 consecutive daily training sessions, while their eye movements were recorded. Speed stacking is a high-speed sensorimotor task that requires grasping, moving, rotating, and placing of objects. The following main results emerged. Throughout practice, the eyes led the hands, displayed by a positive eye-hand time span. Moreover, visual information was gathered for the subsequent manual sub-action, displayed by a positive eye-hand unit span. With automatization, the eye-hand time span became shorter, yet it increased when corrected by the decreasing trial duration. In addition, fixations were mainly allocated to the goal positions of the right hand or objects in the right hand. The number of fixations decreased while the fixation rate remained constant. Importantly, all participants fixated on the same task-relevant locations in a similar scan path across training days, revealing a long-term memory-based mode of attention control after automatization of a high-speed sensorimotor task.
Neggers, SFW; Bekkering, H
In the present study, we integrated two recent, at first sight contradictory findings regarding the question whether saccadic eye movements can be generated to a newly presented target during an ongoing hand movement. Saccades were measured during so-called adaptive and sustained pointing conditions
Full Text Available Experimental evidence suggests the existence of a sophisticated brain circuit specifically dedicated to reach-to-grasp planning and execution, both in human and non human primates (Castiello, 2005. Studies accomplished by means of neuroimaging techniques suggest the hypothesis of a dichotomy between a reach-to-grasp circuit, involving the intraparietal area (AIP, the dorsal and ventral premotor cortices (PMd and PMv - Castiello and Begliomini, 2008; Filimon, 2010 and a reaching circuit involving the medial intraparietal area (mIP and the Superior Parieto-Occipital Cortex (SPOC (Culham et al., 2006. However, the time course characterizing the involvement of these regions during the planning and execution of these two types of movements has yet to be delineated. A functional magnetic resonance imaging (fMRI study has been conducted, including reach-to grasp and reaching only movements, performed towards either a small or a large stimulus, and Finite Impulse Response model (FIR - Henson, 2003 was adopted to monitor activation patterns from stimulus onset for a time window of 10 seconds duration. Data analysis focused on brain regions belonging either to the reaching or to the grasping network, as suggested by Castiello & Begliomini (2008.Results suggest that reaching and grasping movements planning and execution might share a common brain network, providing further confirmation to the idea that the neural underpinnings of reaching and grasping may overlap in both spatial and temporal terms (Verhagen et al., 2013.
Meguerditchian, Adrien; Calcutt, Sarah E.; Lonsdorf, Elizabeth V.; Ross, Stephen R.; Hopkins, William D.
Predominance of right-handedness has historically been considered as a hallmark of human evolution. Whether nonhuman primates exhibit population-level manual bias remains a controversial topic. Here we investigated the hypothesis that bimanual coordinated activities may be a key-behavior in our ancestors for the emergence and evolution of human population-level right-handedness. To this end, we collected data on hand preferences in 35 captive gorillas (Gorilla gorilla) during simple unimanual reaching and for bimanual coordinated feeding. Unimanual reaching consisted of grasping food on the ground while bimanual feeding consisted of using one hand for holding a food and processing the food item by the opposite hand. No population-level manual bias was found for unimanual actions but, in contrast, gorillas exhibited a significant population-level right-handedness for the bimanual actions. Moreover, the degree of right-handedness for bimanual feeding exceeds any other known reports of hand use in primates, suggesting that lateralization for bimanual feeding is robust in captive gorillas. The collective evidence is discussed in the context of potential continuity of handedness between human and nonhuman primates. PMID:20033918
Esposti, Roberto; Bruttini, Carlo; Bolzoni, Francesco; Cavallari, Paolo
During goal-directed arm movements, the eyes, head, and arm are coordinated to look at and reach the target. We examined whether the expectancy of visual information about the target modifies Anticipatory Postural Adjustments (APAs). Ten standing subjects had to (1) move the eyes, head and arm, so as to reach, with both gaze and index-finger, a target of known position placed outside their visual field (Gaze-Reach); (2) look at the target while reaching it (Reach in Full Vision); (3) keep the gaze away until having touched it (Reach then Gaze) and (4) just Gaze without Reach the target. We recorded eye, head, right arm, and acromion kinematics, EMGs from upper- and lower-limb muscles, and forces exerted on the ground. In Gaze-Reach, two coordination strategies were found: when gaze preceded arm muscle recruitment (Gaze-first) and when the opposite occurred (Reach-first). APAs in acromion kinematics, leg muscles, and ground forces started significantly earlier in Gaze-first vs. Reach-first (mean time advance: 44.3 ± 8.9 ms), as it was in Reach in Full Vision vs. Reach then Gaze (39.5 ± 7.9 ms). The Gaze-first to Reach-first time-shift was similar to that between Reach in Full Vision and Reach then Gaze (p = 0.58). Moreover, Gaze without Reach data witnessed that the head-induced postural actions did not affect the APA onset in Gaze-first and Reach-first. In conclusion, in Gaze-first, the central control of posture considers visual information while planning the movement, like in Reach in Full Vision; while Reach-first is more similar to Reach then Gaze, where vision is not required.
Hanassy, S; Botvinnik, A; Flash, T; Hochner, B
The bend propagation involved in the stereotypical reaching movement of the octopus arm has been extensively studied. While these studies have analyzed the kinematics of bend propagation along the arm during its extension, possible length changes have been ignored. Here, the elongation profiles of the reaching movements of Octopus vulgaris were assessed using three-dimensional reconstructions. The analysis revealed that, in addition to bend propagation, arm extension movements involve elongation of the proximal part of the arm, i.e., the section from the base of the arm to the propagating bend. The elongations are quite substantial and highly variable, ranging from an average strain along the arm of -0.12 (i.e. shortening) up to 1.8 at the end of the movement (0.57 ± 0.41, n = 64 movements, four animals). Less variability was discovered in an additional set of experiments on reaching movements (0.64 ± 0.28, n = 30 movements, two animals), where target and octopus positions were kept more stationary. Visual observation and subsequent kinematic analysis suggest that the reaching movements can be broadly segregated into two groups. The first group involves bend propagation beginning at the base of the arm and propagating towards the arm tip. In the second, the bend is formed or present more distally and reaching is achieved mainly by elongation and straightening of the segment proximal to the bend. Only in the second type of movements is elongation significantly positively correlated with the distance of the bend from the target. We suggest that reaching towards a target is generated by a combination of both propagation of a bend along the arm and arm elongation. These two motor primitives may be combined to create a broad spectrum of reaching movements. The dynamical model, which recapitulates the biomechanics of the octopus muscular hydrostatic arm, suggests that achieving the observed elongation requires an extremely low ratio of longitudinal to transverse muscle
Stella Maris Michaelsen
Full Text Available The purpose of this study was using an accelerometer to access the kinematics of reach-to-grasp movements in subjects with hemiparesis. Eight subjects (59.4 ± 6.9 years old with chronic hemiparesis (50.9 ± 25.8 months post-stroke participated in this study. Kinematic assessment was performed using a triaxial accelerometer (EMG Systems, Brazil attached to the subjects' forearm. Ten reach-to-grasp movements of grabbing a 500ml-size bottle were performed by the subjects with the paretic and the non-paretic upper limbs (ULs. The following space-temporal variables were calculated and used to compare the paretic and non-paretic ULs: movement time (MT, time to reach the peak velocity, absolute and relative (TPV and TPV%MT, relative deceleration duration (DEC%MT, time to peak acceleration (TPA and peak hand acceleration (PA. Movements were slower in the paretic UL with increased MT, TPA and DEC. The accelerometer allowed to identify of changes in reaching-to-grasp movements of subjects with hemiparesis. When complex systems are not available, accelerometers can be an alternative to measure UL movements.
Kudo, Naoki; Choi, Kyuheong; Kagawa, Takahiro; Uno, Yoji
It is well known that planar reaching movements of the human shoulder and elbow joints have invariant features: roughly straight hand paths and bell-shaped velocity profiles. The optimal control models with the criteria of smoothness or precision, which determine a unique movement pattern, predict such features of hand trajectories. In this letter on expanding the research on simple arm reaching movements, we examine whether the smoothness criteria can be applied to whole-body reaching movements with many degrees of freedom. Determining a suitable joint trajectory in the whole-body reaching movement corresponds to the optimization problem with constraints, since body balance must be maintained during a motion task. First, we measured human joint trajectories and ground reaction forces during whole-body reaching movements, and confirmed that subjects formed similar movements with common characteristics in the trajectories of the hand position and body center of mass. Second, we calculated the optimal trajectories according to the criteria of torque and muscle-tension smoothness. While the minimum torque change trajectories were not consistent with the experimental data, the minimum muscle-tension change model was able to predict the stereotyped features of the measured trajectories. To explore the dominant effects of the extension from the torque change to the muscle-tension change, we introduced a weighted torque change cost function. Considering the maximum voluntary contraction (MVC) force of the muscle as the weighting factor of each joint torque, we formulated the weighted torque change cost as a simplified version of the minimum muscle-tension change cost. The trajectories owing to the minimum weighted torque change criterion also showed qualitative agreement with the common features of the measured data. Proper estimation of the MVC forces in the body joints is essential to reproduce human whole-body movements according to the minimum muscle-tension change
Reichenbach, Alexandra; Thielscher, Axel; Peer, Angelika; Bülthoff, Heinrich H; Bresciani, Jean-Pierre
Seemingly effortless, we adjust our movements to continuously changing environments. After initiation of a goal-directed movement, the motor command is under constant control of sensory feedback loops. The main sensory signals contributing to movement control are vision and proprioception. Recent neuroimaging studies have focused mainly on identifying the parts of the posterior parietal cortex (PPC) that contribute to visually guided movements. We used event-related TMS and force perturbations of the reaching hand to test whether the same sub-regions of the left PPC contribute to the processing of proprioceptive-only and of multi-sensory information about hand position when reaching for a visual target. TMS over two distinct stimulation sites elicited differential effects: TMS applied over the posterior part of the medial intraparietal sulcus (mIPS) compromised reaching accuracy when proprioception was the only sensory information available for correcting the reaching error. When visual feedback of the hand was available, TMS over the anterior intraparietal sulcus (aIPS) prolonged reaching time. Our results show for the first time the causal involvement of the posterior mIPS in processing proprioceptive feedback for online reaching control, and demonstrate that distinct cortical areas process proprioceptive-only and multi-sensory information for fast feedback corrections.
Corbetta, D; Thelen, E
The development of hand preference in infant reaching is marked by several lateral fluctuations. This study investigated whether similar lateral fluctuations were present in infants' spontaneous, nonreaching, and freely performed movements. We collected reaching and nonreaching movements kinematics in 4 infants that we followed longitudinally during their 1st year. In their 4th year, we assessed the direction of their hand preference. We found that lateral biases in spontaneous, nonreaching movements in the 1st year showed several shifts that were similar to those observed in reaching. Despite these shifts, all 4 infants traversed a short period of right-handedness. This right-handedness matched the direction of their hand preference at 3 years of age. We propose that shifts in the development of hand preference in the 1st year are linked to successive reorganizations of the motor system. These reorganizations take place as infants learn to sit, crawl, and walk.
Mueller, Stefanie; Fiehler, Katja
Previous studies demonstrated that an effector movement intervening between encoding and reaching to a proprioceptive target determines the underlying reference frame: proprioceptive reach targets are represented in a gaze-independent reference frame if no movement occurs but are represented with respect to gaze after an effector movement (Mueller and Fiehler, 2014a). The present experiment explores whether an effector movement leads to a switch from a gaze-independent, body-centered reference frame to a gaze-dependent reference frame or whether a gaze-dependent reference frame is employed in addition to a gaze-independent, body-centered reference frame. Human participants were asked to reach in complete darkness to an unseen finger (proprioceptive target) of their left target hand indicated by a touch. They completed 2 conditions in which the target hand remained either stationary at the target location (stationary condition) or was actively moved to the target location, received a touch and was moved back before reaching to the target (moved condition). We dissociated the location of the movement vector relative to the body midline and to the gaze direction. Using correlation and regression analyses, we estimated the contribution of each reference frame based on horizontal reach errors in the stationary and moved conditions. Gaze-centered coding was only found in the moved condition, replicating our previous results. Body-centered coding dominated in the stationary condition while body- and gaze-centered coding contributed equally strong in the moved condition. Our results indicate a shift from body-centered to combined body- and gaze-centered coding due to an effector movement before reaching towards proprioceptive targets.
In primates, control of the limb depends on many cortical areas. Whereas specialized parietofrontal circuits have been proposed for different movements in macaques, functional neuroimaging in humans has revealed widespread, overlapping activations for hand and eye movements and for movements such as reaching and grasping. This review examines the involvement of frontal and parietal areas in hand and arm movements in humans as revealed with functional neuroimaging. The degree of functional specialization, possible homologies with macaque cortical regions, and differences between frontal and posterior parietal areas are discussed, as well as a possible organization of hand movements with respect to different spatial reference frames. The available evidence supports a cortical organization along gradients of sensory (visual to somatosensory) and effector (eye to hand) preferences.
Srinivasan, Lakshminarayan; da Silva, Marco
We routinely generate reaching arm movements to function independently. For paralyzed users of upper extremity neural prosthetic devices, flexible, high-performance reaching algorithms will be critical to restoring quality-of-life. Previously, algorithms called real-time reach state equations (RSE) were developed to integrate the user's plan and execution-related neural activity to drive reaching movements to arbitrary targets. Preliminary validation under restricted conditions suggested that RSE might yield dramatic performance improvements. Unfortunately, real-world applications of RSE have been impeded because the RSE assumes a fixed, known arrival time. Recent animal-based prototypes attempted to break the fixed-arrival-time assumption by proposing a standard model (SM) that instead restricted the user's movements to a fixed, known set of targets. Here, we leverage general purpose filter design (GPFD) to break both of these critical restrictions, freeing the paralyzed user to make reaching movements to arbitrary target sets with various arrival times and definitive stopping. In silico validation predicts that the new approach, GPFD-RSE, outperforms the SM while offering greater flexibility. We demonstrate the GPFD-RSE against SM in the simulated control of an overactuated 3-D virtual robotic arm with a real-time inverse kinematics engine.
Asmussen, M J; Bailey, A Z; Nelson, A J
The neural command required to coordinate a multi-joint movement is inherently complex. During multi-joint movement of the limb, the force created from movement at one joint may create a torque at a second joint known as an interaction torque. Interaction torques may be assistive or resistive thereby aiding or opposing the motion of the second joint, respectively. For movement to be effectively controlled, the central nervous system should modulate neural output to the muscles to appropriately account for interaction torques. The present study examined the neural output from the primary motor cortex before and during reaching movements that required different combinations of assistive and resistive interaction torques occurring at the shoulder and elbow joints. Using transcranial magnetic stimulation to probe neural output from the primary motor cortex, results indicate that corticospinal output controlling the upper arm is related to resistive interaction torques occurring at the shoulder joint. Further, cortical output to bi-articular muscles is associated with interaction torque and this may be driven by the fact that these muscles are in an advantageous position to control torques produced between inter-connection segments. Humans have a tendency to avoid reaching movements that involve resistive interaction torques and this may be driven by the requirement of increased neural output associated with these movements.
Full Text Available Abstract This study, conducted in a group of nine chronic patients with right-side hemiparesis after stroke, investigated the effects of a robotic-assisted rehabilitation training with an upper limb robotic exoskeleton for the restoration of motor function in spatial reaching movements. The robotic assisted rehabilitation training was administered for a period of 6 weeks including reaching and spatial antigravity movements. To assess the carry-over of the observed improvements in movement during training into improved function, a kinesiologic assessment of the effects of the training was performed by means of motion and dynamic electromyographic analysis of reaching movements performed before and after training. The same kinesiologic measurements were performed in a healthy control group of seven volunteers, to determine a benchmark for the experimental observations in the patients’ group. Moreover degree of functional impairment at the enrolment and discharge was measured by clinical evaluation with upper limb Fugl-Meyer Assessment scale (FMA, 0–66 points, Modified Ashworth scale (MA, 0–60 pts and active ranges of motion. The robot aided training induced, independently by time of stroke, statistical significant improvements of kinesiologic (movement time, smoothness of motion and clinical (4.6 ± 4.2 increase in FMA, 3.2 ± 2.1 decrease in MA parameters, as a result of the increased active ranges of motion and improved co-contraction index for shoulder extension/flexion. Kinesiologic parameters correlated significantly with clinical assessment values, and their changes after the training were affected by the direction of motion (inward vs. outward movement and position of target to be reached (ipsilateral, central and contralateral peripersonal space. These changes can be explained as a result of the motor recovery induced by the robotic training, in terms of regained ability to execute single joint movements and of improved
Goncharenko, Igor; Svinin, Mikhail; Hosoe, Shigeyuki; Forstmann, Sven
An analysis of human reaching movements in the task of mass transport is presented. Two models, the minimum hand jerk (MJC) and the minimum driving hand force-change (MFCC), are used for modelling and verification of experimental data. The data were collected with a haptic system supporting object dynamics simulation in real time. The
Reichenbach, Alexandra; Thielscher, Axel; Peer, Angelika
neuroimaging studies have focused mainly on identifying the parts of the posterior parietal cortex (PPC) that contribute to visually guided movements. We used event-related TMS and force perturbations of the reaching hand to test whether the same sub-regions of the left PPC contribute to the processing...... of proprioceptive-only and of multi-sensory information about hand position when reaching for a visual target. TMS over two distinct stimulation sites elicited differential effects: TMS applied over the posterior part of the medial intraparietal sulcus (mIPS) compromised reaching accuracy when proprioception...... was the only sensory information available for correcting the reaching error. When visual feedback of the hand was available, TMS over the anterior intraparietal sulcus (aIPS) prolonged reaching time. Our results show for the first time the causal involvement of the posterior mIPS in processing proprioceptive...
Full Text Available Individuals with cervical spinal cord injury (SCI that causes tetraplegia are challenged with dramatic sensorimotor deficits. However, certain rehabilitation techniques may significantly enhance their autonomy by restoring reach-to-grasp movements. Among others, evidence of motor imagery (MI benefits for neurological rehabilitation of upper limb movements is growing. This literature review addresses motor imagery (MI effectiveness during reach-to-grasp rehabilitation after tetraplegia. Among articles from MEDLINE published between 1966 and 2015, we selected ten studies including 34 participants with C4 to C7 tetraplegia and 22 healthy controls published during the last fifteen years. We found that MI of possible non-paralyzed movements improved reach-to-grasp performance by i increasing both tenodesis grasp capabilities and muscle strength, ii decreasing movement time, and trajectory variability, and, iii reducing the abnormally increased brain activity. MI can also strengthen motor commands by potentiating recruitment and synchronization of motoneurons, which leads to improved recovery. These improvements reflect brain adaptations induced by MI. Furthermore, MI can be used to control brain computer interfaces (BCI that successfully restore grasp capabilities. These results highlight the growing interest for MI and its potential to recover functional grasping in individuals with tetraplegia, and motivate the need for further studies to substantiate it.
Full Text Available In human reach-to-grasp movement, visual occlusion of a target object leads to a larger peak grip aperture compared to conditions where online vision is available. However, no previous computational and neural network models for reach-to-grasp movement explain the mechanism of this effect. We simulated the effect of online vision on the reach-to-grasp movement by proposing a computational control model based on the hypothesis that the grip aperture is controlled to compensate for both motor variability and sensory uncertainty. In this model, the aperture is formed to achieve a target aperture size that is sufficiently large to accommodate the actual target; it also includes a margin to ensure proper grasping despite sensory and motor variability. To this end, the model considers: i the variability of the grip aperture, which is predicted by the Kalman filter, and ii the uncertainty of the object size, which is affected by visual noise. Using this model, we simulated experiments in which the effect of the duration of visual occlusion was investigated. The simulation replicated the experimental result wherein the peak grip aperture increased when the target object was occluded, especially in the early phase of the movement. Both predicted motor variability and sensory uncertainty play important roles in the online visuomotor process responsible for grip aperture control.
Cunningham, David A; Roelle, Sarah M; Allexandre, Didier; Potter-Baker, Kelsey A; Sankarasubramanian, Vishwanath; Knutson, Jayme S; Yue, Guang H; Machado, Andre G; Plow, Ela B
Motor overflow, typically described in the context of unimanual movements, refers to the natural tendency for a 'resting' limb to move during movement of the opposite limb and is thought to be influenced by inter-hemispheric interactions and intra-cortical networks within the 'resting' hemisphere. It is currently unknown, however, how motor overflow contributes to asymmetric force coordination task accuracy, referred to as bimanual interference, as there is need to generate unequal forces and corticospinal output for each limb. Here, we assessed motor overflow via motor evoked potentials (MEPs) and the regulation of motor overflow via inter-hemispheric inhibition (IHI) and short-intra-cortical inhibition (SICI) using transcranial magnetic stimulation in the presence of unimanual and bimanual isometric force production. All outcomes were measured in the left first dorsal interosseous (test hand) muscle, which maintained 30% maximal voluntary contraction (MVC), while the right hand (conditioning hand) was maintained at rest, 10, 30, or 70% of its MVC. We have found that as higher forces are generated with the conditioning hand, MEP amplitudes at the active test hand decreased and inter-hemispheric inhibition increased, suggesting reduced motor overflow in the presence of bimanual asymmetric forces. Furthermore, we found that subjects with less motor overflow (i.e., reduced MEP amplitudes in the test hemisphere) demonstrated poorer accuracy in maintaining 30% MVC across all conditions. These findings suggest that motor overflow may serve as an adaptive substrate to support bimanual asymmetric force coordination.
Fagard, Jacqueline; Corroyer, Denis
We sought to determine whether laterality is related to interhemispheric transfer and bimanual coordination during development. Children between 3 and 8 years of age were observed. In the first part of the experiment, we devised a continuous index to order the subjects according to their laterality. The laterality index included evaluation of hand and eye preference, and the right-left performance difference. In the second part of the experiment, we used this single index to determine whether laterality is related to interhemispheric transfer and bimanual coordination. Interhemispheric transfer was assessed by means of two tactile transfer tasks and one visuo-manual transfer task. We assessed bimanual coordination using the tapping task and the bimanual crank-rotation task. Results showed that right- and left-hand writers overlap on certain measures of laterality. They confirmed the improvement of interhemispheric transfer at around age 5 years, earlier progress in bimanual coordination with mirror than with parallel movements, and the existence of a relationship between visuo-manual interhemispheric transfer and bimanual coordination. The laterality index was not related to interhemispheric transfer, but it was related to the younger subjects' performance on the bimanual crank-rotation task: the less right handed, the better the bimanual coordination. In addition, on the same bimanual task, crossed hand-eye laterality was associated with better performance.
Joshua L Williams
Full Text Available Prior research on infant reaching has shown that providing infants with repeated opportunities to reach for objects aids the emergence and progression of reaching behavior. This study investigated the effect of movement consequences on the process of learning to reach in pre-reaching infants. Thirty-five infants aged 2.9 months at the onset of the study were randomly assigned to 1 of 3 groups. Two groups received a 14-day intervention to distinct reaching tasks: (1 in a contingent group, a toy target moved and sounded upon contact only, and (2 in a continuous group, the toy moved and sounded continuously, independent of hand-toy contact. A third control group did not receive any intervention; this group’s performance was assessed only on two days at a 15-day interval. Results revealed that infants in the contingent group made the most progress over time compared to the two other groups. Infants in this group made significantly more overall contacts with the sounding/moving toy, and they increased their rate of visually-attended target contacts relative to non-visually-attended target contacts compared to the continuous and control groups. Infants in the continuous group did not differ from the control group on the number of hand-toy contacts nor did they show a change in visually-attended target versus non-visually-attended target contacts ratio over time. However, they did show an increase in movement speed, presumably in an attempt to attain the moving toy. These findings highlight the importance of contingent movement consequences as a critical reinforcer for the selection of action and motor learning in early development. Through repeated opportunities to explore movement consequences, infants discover and select movements that are most successful to the task-at-hand. This study further demonstrates that distinct sensory-motor experiences can have a significant impact on developmental trajectories and can influence the skills young infants
Rand, Miya K; Squire, Linda M; Stelmach, George E
This study investigates coordination between hand transport and grasp movement components by examining a hypothesis that the hand location, relative to the object, in which aperture closure is initiated remains relatively constant under a wide range of transport speed. Subjects made reach-to-grasp movements to a dowel under four speed conditions: slow, comfortable, fast but comfortable, and maximum (i.e., as fast as possible). The distance traveled by the wrist after aperture reached its maximum (aperture closure distance) increased with an increase of transport speed across the speed conditions. This finding rejected the hypothesis and suggests that the speed of hand transport is taken into account in aperture closure initiation. Within each speed condition, however, the closure distance exhibited relatively small variability across trials, even though the total distance traveled by the wrist during the entire transport movement varied from trial to trial. The observed stability in aperture closure distance across trials implies that the hand distance to the object plays an important role in the control law governing the initiation of aperture closure. Further analysis showed that the aperture closure distance depended on the amplitude of peak aperture as well as hand velocity and acceleration. To clarify the form of the above control law, we analyzed four different mathematical models, in which a decision to initiate grasp closure is made as soon as a specific movement parameter (wrist distance to target or transport time) crosses a threshold that is either a constant value or a function of the above-mentioned other movement-related parameters. Statistical analysis performed across all movement conditions revealed that the control law model (according to which grasp initiation is made when hand distance to target becomes less than a certain linear function of aperture amplitude, hand velocity, and hand acceleration) produced significantly smaller residual errors
Bundy, David T.; Pahwa, Mrinal; Szrama, Nicholas; Leuthardt, Eric C.
Objective. Electrocorticography (ECoG) signals have emerged as a potential control signal for brain-computer interface (BCI) applications due to balancing signal quality and implant invasiveness. While there have been numerous demonstrations in which ECoG signals were used to decode motor movements and to develop BCI systems, the extent of information that can be decoded has been uncertain. Therefore, we sought to determine if ECoG signals could be used to decode kinematics (speed, velocity, and position) of arm movements in 3D space. Approach. To investigate this, we designed a 3D center-out reaching task that was performed by five epileptic patients undergoing temporary placement of ECoG arrays. We used the ECoG signals within a hierarchical partial-least squares (PLS) regression model to perform offline prediction of hand speed, velocity, and position. Main Results. The hierarchical PLS regression model enabled us to predict hand speed, velocity, and position during 3D reaching movements from held-out test sets with accuracies above chance in each patient with mean correlation coefficients between 0.31 and 0.80 for speed, 0.27 and 0.54 for velocity, and 0.22 and 0.57 for position. While beta band power changes were the most significant features within the model used to classify movement and rest, the local motor potential and high gamma band power changes, were the most important features in the prediction of kinematic parameters. Significance. We believe that this study represents the first demonstration that truly three-dimensional movements can be predicted from ECoG recordings in human patients. Furthermore, this prediction underscores the potential to develop BCI systems with multiple degrees of freedom in human patients using ECoG.
Full Text Available This paper focuses on a dynamic sensory-motor control mechanism of reaching movements for a musculo-skeletal redundant arm model. The formulation of a musculo-skeletal redundant arm system, which takes into account non-linear muscle properties obtained by some physiological understandings, is introduced and numerical simulations are perfomed. The non-linear properties of muscle dynamics make it possible to modulate the viscosity of the joints, and the end point of the arm converges to the desired point with a simple task-space feedback when adequate internal forces are chosen, regardless of the redundancy of the joint. Numerical simulations were performed and the effectiveness of our control scheme is discussed through these results. The results suggest that the reaching movements can be achieved using only a simple task-space feedback scheme together with the internal force effect that comes from non-linear properties of skeletal muscles without any complex mathematical computation such as an inverse dynamics or optimal trajectory derivation. In addition, the dynamic damping ellipsoid for evaluating how the internal forces can be determined is introduced. The task-space feedback is extended to the ‘virtual spring-damper hypothesis’ based on the research by Arimoto et al. (2006 to reduce the muscle output forces and heterogeneity of convergence depending on the initial state and desired position. The research suggests a new direction for studies of brain-motor control mechanism of human movements.
Guastello, Stephen J; Nathan, Dominic E; Johnson, Michelle J
The principles of attractors and Lyapunov exponents were used to develop a reaching-to-grasp model for use in a robotic therapy system for stroke patients. Previously known models for these movements, the fifth order minimum jerk and the seventh order polynomial, do not account for the change in grasp aperture of the hand. The Lyapunov model was tested with reaching-to-grasp movements performed by five neurologically intact subjects and produced an average R-square = .97 over 15 replications for 41 different task events, reflecting a notable advantage over the fifth order (average R-square = .58) and seventh order (average R-square = .67) models. A similar level of success was obtained for the Lyapunov model that was specific to grasp aperture. The results indicated that intentional movements can be accurately characterized as attractor trajectories, and as functions of position along two Cartesian coordinates rather than as functions of time. The Lyapunov exponent model requires fewer parameters and provides an efficient platform for real-time implementation.
DiZio, P; Lackner, J R
When reaching movements are made during passive constant velocity body rotation, inertial Coriolis accelerations are generated that displace both movement paths and endpoints in their direction. These findings directly contradict equilibrium point theories of movement control. However, it has been argued that these movement errors relate to subjects sensing their body rotation through continuing vestibular activity and making corrective movements. In the present study, we evaluated the reaching movements of five labyrinthine-defective subjects (lacking both semicircular canal and otolith function) who cannot sense passive body rotation in the dark and five age-matched, normal control subjects. Each pointed 40 times in complete darkness to the location of a just extinguished visual target before, during, and after constant velocity rotation at 10 rpm in the center of a fully enclosed slow rotation room. All subjects, including the normal controls, always felt completely stationary when making their movements. During rotation, both groups initially showed large deviations of their movement paths and endpoints in the direction of the transient Coriolis forces generated by their movements. With additional per-rotation movements, both groups showed complete adaptation of movement curvature (restoration of straight-line reaches) during rotation. The labyrinthine-defective subjects, however, failed to regain fully accurate movement endpoints after 40 reaches, unlike the control subjects who did so within 11 reaches. Postrotation, both groups' movements initially had mirror image curvatures to their initial per-rotation reaches; the endpoint aftereffects were significantly different from prerotation baseline for the control subjects but not for the labyrinthine-defective subjects reflecting the smaller amount of endpoint adaptation they achieved during rotation. The labyrinthine-defective subjects' movements had significantly lower peak velocity, higher peak elevation
Loukopoulos, L. D.; Engelbrecht, S. F.; Berthier, N. E.
Individuals are assumed to plan reach-and-grasp movements by using two separate processes. In 1 of the processes, extrinsic (direction, distance) object information is used in planning the movement of the arm that transports the hand to the target location (transport planning); whereas in the other, intrinsic (shape) object information is used in planning the preshaping of the hand and the grasping of the target object (manipulation planning). In 2 experiments, the authors used primes to provide information to participants (N = 5, Experiment 1; N = 6, Experiment 2) about extrinsic and intrinsic object properties. The validity of the prime information was systematically varied. The primes were succeeded by a cue, which always correctly identified the location and shape of the target object. Reaction times were recorded. Four models of transport and manipulation planning were tested. The only model that was consistent with the data was 1 in which arm transport and object manipulation planning were postulated to be independent processes that operate partially in parallel. The authors suggest that the processes involved in motor planning before execution are primarily concerned with the geometric aspects of the upcoming movement but not with the temporal details of its execution.
Teresa De Sanctis
Full Text Available BACKGROUND: In non-human primates grasp-related sensorimotor transformations are accomplished in a circuit involving the anterior intraparietal sulcus (area AIP and both the ventral and the dorsal sectors of the premotor cortex (vPMC and dPMC, respectively. Although a human homologue of such a circuit has been identified, the time course of activation of these cortical areas and how such activity relates to specific kinematic events has yet to be investigated. METHODOLOGY/PRINCIPAL FINDINGS: We combined kinematic and event-related potential techniques to explicitly test how activity within human grasping-related brain areas is modulated in time. Subjects were requested to reach towards and grasp either a small stimulus using a precision grip (i.e., the opposition of index finger and thumb or a large stimulus using a whole hand grasp (i.e., the flexion of all digits around the stimulus. Results revealed a time course of activation starting at the level of parietal regions and continuing at the level of premotor regions. More specifically, we show that activity within these regions was tuned for specific grasps well before movement onset and this early tuning was carried over--as evidenced by kinematic analysis--during the preshaping period of the task. CONCLUSIONS/SIGNIFICANCE: Data are discussed in terms of recent findings showing a marked differentiation across different grasps during premovement phases which was carried over into subsequent movement phases. These findings offer a substantial contribution to the current debate about the nature of the sensorimotor transformations underlying grasping. And provide new insights into the detailed movement information contained in the human preparatory activity for specific hand movements.
Han, Jia; Waddington, Gordon; Adams, Roger; Anson, Judith
It has been proposed that asymmetry between the upper limbs in the utilization of proprioceptive feedback arises from functional differences in the roles of the preferred and non-preferred hands during bimanual tasks. The present study investigated unimanual and bimanual proprioceptive performance in right- and left-handed young adults with an active finger pinch movement discrimination task. With visual information removed, participants were required to make absolute judgments about the extent of pinch movements made to physical stops, either by one hand, or by both hands concurrently, with the sequence of presented movement extents varied randomly. Discrimination accuracy scores were derived from participants' responses using non-parametric signal detection analysis. Consistent with previous findings, a non-dominant hand/hemisphere superiority effect was observed, where the non-dominant hands of right- and left-handed individuals performed overall significantly better than their dominant hands. For all participants, bimanual movement discrimination scores were significantly lower than scores obtained in the unimanual task. However, the magnitude of the performance reduction, from the unimanual to the bimanual task, was significantly greater for left-handed individuals. The effect whereby bimanual proprioception was disproportionately affected in left-handed individuals could be due to enhanced neural communication between hemispheres in left-handed individuals leading to less distinctive separation of information obtained from the two hands in the cerebral cortex.
Utley, A.; Steenbergen, B.
Bimanual coordination is a field that has generated much research interest. It is clear that when hands move simultaneously there is a tendency for such movements to be synchronized (Kelso 1979). This paper provides an overview of past and current work in the area of bimanual coordination looking at
Meguerditchian, Adrien; Calcutt, Sarah E; Lonsdorf, Elizabeth V; Ross, Stephen R; Hopkins, William D
Predominance of right-handedness has historically been considered as a hallmark of human evolution. Whether nonhuman primates exhibit population-level manual bias remains a controversial topic. Here, we investigated the hypothesis that bimanual coordinated activities may be a key-behavior in our ancestors for the emergence and evolution of human population-level right-handedness. To this end, we collected data on hand preferences in 35 captive gorillas (Gorilla gorilla) during simple unimanual reaching and for bimanual coordinated feeding. Unimanual reaching consisted of grasping food on the ground, while bimanual feeding consisted of using one hand for holding a food and processing the food item by the opposite hand. No population-level manual bias was found for unimanual actions but, in contrast, gorillas exhibited a significant population-level right-handedness for the bimanual actions. Moreover, the degree of right-handedness for bimanual feeding exceeds any other known reports of hand use in primates, suggesting that lateralization for bimanual feeding is robust in captive gorillas. The collective evidence is discussed in the context of potential continuity of handedness between human and nonhuman primates.
Mariana Martins dos Santos
Full Text Available OBJETIVOS: verificar a influência das propriedades dos objetos nos ajustes realizados por lactentes típicos e com Síndrome de Down (SD dos quatro aos oito meses de idade ao alcançar e apreender objetos. MÉTODOS: 16 lactentes, avaliados uma vez ao mês dos 4 aos 8 meses, sendo oito típicos e oito com SD. Quatro objetos esféricos (maleável grande, maleável pequeno, rígido grande e rígido pequeno foram apresentados, e os cinco primeiros movimentos válidos foram registrados para análise das variáveis: ajuste proximal (uni e bimanual, ajuste distal (orientação da palma, abertura da mão e apreensão do objeto. RESULTADOS: os lactentes típicos apresentaram mais ajuste bimanual para objetos grandes aos seis e oito meses e os com SD aos sete meses. Quanto aos ajustes distais, os lactentes típicos variaram seu comportamento enquanto os com SD apresentaram uso predominante da posição oblíqua. Em geral, o grupo típico apresentou maior sucesso na apreensão dos objetos rígidos e maleável pequeno quando comparados aos lactentes com SD. CONCLUSÕES: Os lactentes com SD apresentaram menor variedade de ajustes o que levou a um menor sucesso na apreensão, possivelmente devido a restrições intrínsecas da SD.OBJECTIVES: to verify the influence that properties of objects have on the reaching and grasping adjustments made by infants with and without Down syndrome (DS between four to eight months of age. METHODS: 16 infants, eight typical and eight with DS, were evaluated once a month from months 4 to 8. Four spherical objects (large soft, small soft, large hard and small hard were offered and the first five valid movements were recorded for analysis of the variables: proximal adjustment (uni- and bimanual, distal adjustments (palm orientation, hand opening and grasping of the object. RESULTS: the typical infants displayed greater bimanual adjustment for large objects at six and eight months and those with DS at seven months. As for distal
Sacrey, Lori-Ann R; Alaverdashvili, Mariam; Whishaw, Ian Q
Many animal species use their forelimbs to assist in eating, such as occurs in a reach-to-eat task (skilled reaching) in which a forelimb is extended to grasp food that is placed in the mouth for eating. It is unclear the extent to which the skilled reaching movements of different species share common ancestry and so are homologous or evolved independently and so are analogous (homoplasy). Here hand shaping (the movements of the hand and digits) that occur as the hand is transported to the target, were examined using high-speed (1000 frames/s) video recording and kinematic measurement (Peak Motus) in the rat (Rattus norvegicus) and human (Homo sapiens). Ten movement similarities were identified from the point that the limb initiated transport towards the food item to the point that the food was grasped. The digits were closed and semi-flexed as the hand was lifted (released from a substrate) and supinated. They closed further as the hand was collected for aiming. They then extended as the hand was transported to the target and then opened in conjunction with pronation to orient the hand for grasping (manipulation). Finally the digits were flexed and closed for grasping. These movements occurred at approximately the same point of limb transport in both species even though the rat used a whole paw grasp and the humans used a pincer grasp. Bushbabies (Galago garnettii), titi monkeys (Callicebus brunneus), rhesus monkeys (Macaca mulatta) and the bonobo (Pan paniscus) displayed similar hand shaping in skilled reaching despite species differences in grasping movements. Homologous hand shaping in the rodent clade and the primate clade and within the primate lineage is discussed in relation to its possible derivation from hand shaping movements associated with stepping.
Rymer W Zev
Full Text Available Abstract Background and purpose Providing active assistance to complete desired arm movements is a common technique in upper extremity rehabilitation after stroke. Such active assistance may improve recovery by affecting somatosensory input, motor planning, spasticity or soft tissue properties, but it is labor intensive and has not been validated in controlled trials. The purpose of this study was to investigate the effects of robotically administered active-assistive exercise and compare those with free reaching voluntary exercise in improving arm movement ability after chronic stroke. Methods Nineteen individuals at least one year post-stroke were randomized into one of two groups. One group performed 24 sessions of active-assistive reaching exercise with a simple robotic device, while a second group performed a task-matched amount of unassisted reaching. The main outcome measures were range and speed of supported arm movement, range, straightness and smoothness of unsupported reaching, and the Rancho Los Amigos Functional Test of Upper Extremity Function. Results and discussion There were significant improvements with training for range of motion and velocity of supported reaching, straightness of unsupported reaching, and functional movement ability. These improvements were not significantly different between the two training groups. The group that performed unassisted reaching exercise improved the smoothness of their reaching movements more than the robot-assisted group. Conclusion Improvements with both forms of exercise confirmed that repeated, task-related voluntary activation of the damaged motor system is a key stimulus to motor recovery following chronic stroke. Robotically assisting in reaching successfully improved arm movement ability, although it did not provide any detectable, additional value beyond the movement practice that occurred concurrently with it. The inability to detect any additional value of robot-assisted reaching
de Boer, Betteco J; Peper, C E; Beek, Peter J
Developmental changes in bimanual coordination were examined in four age groups: 6/7, 10/11, 14/15 years, and young adults. Temporal coupling was assessed through the stabilizing contributions of interlimb interactions related to planning, error correction, and reflexes during rhythmic wrist movements, by comparing various unimanual and bimanual tasks involving passive and active movements. Spatial coupling was assessed via bimanual line-circle drawing. With increasing age, temporal stability improved. Relative contributions of planning and reflex interactions to the achieved stability did not change, whereas error correction improved. In-phase and antiphase coordination developed at similar rates; implications of this result were discussed in terms of mirror-activity inhibition. Overall spatial drawing performance (circularity, variability, smoothness) improved with age, and spatial interference was smaller in adults than children. Whereas temporal coupling increased from 6/7 years to adulthood, spatial coupling changed mainly after 14/15 years. This difference in the development of temporal and spatial coupling corresponds to the anterior-posterior direction of corpus callosum myelination as reported in the literature.
Geerdink, Yvonne; Aarts, Pauline; Geurts, Alexander C.
The goal of this study was to determine the progression of manual dexterity during 6 weeks (54 h) (modified) constraint-induced movement therapy ((m)CIMT) followed by 2 weeks (18 h) bimanual training (BiT) in children with unilateral spastic cerebral palsy (CP), to establish whether and when a maximal training effect was reached and which factors…
Neely, Kristina A; Morris, Laura J
The present work provides an empirical test of the Dynamic Field Theory of visuospatial cognition. The Dynamic Field Theory is a bi-stable neural network model applied to explain how visual information is integrated during the preparation of reaching responses (Erlhagen and Schöner). The dynamic field theory posits that motor cortices develop peaks of activation for each possible target in the visual field. Targets that are close in space produce neural peaks with overlapping distributions, whereas targets that are far apart produce distinct peaks with non-overlapping distributions. As such, the Dynamic Field Theory predicts reaction times to potential targets that are close in space will be faster than those to targets that are far apart. The present work examined how proximal and distal distractors impact reaction time in an upper-limb reaching task. The results demonstrated that distal distractors result in prolonged reaction times compared to proximal distractors. We suggest that reaction time represents the time required to inhibit neural activity representing the location of the distractor. Thus, prolonged reaction times observed for distal distractors reflect the temporal demands associated with the competition of two non-overlapping distributions of activity in the brain. These findings support the tenets of the Dynamic Field Theory and demonstrate that non-target stimuli in the visual field can influence movement preparation.
Pigeon, Pascale; Bortolami, Simone B; DiZio, Paul; Lackner, James R
When reaching movements involve simultaneous trunk rotation, additional interaction torques are generated on the arm that are absent when the trunk is stable. To explore whether the CNS compensates for such self-generated interaction torques, we recorded hand trajectories in reaching tasks involving various amplitudes and velocities of arm extension and trunk rotation. Subjects pointed to three targets on a surface slightly above waist level. Two of the target locations were chosen so that a similar arm configuration relative to the trunk would be required for reaching to them, one of these targets requiring substantial trunk rotation, the other very little. Significant trunk rotation was necessary to reach the third target, but the arm's radial distance to the body remained virtually unchanged. Subjects reached at two speeds-a natural pace (slow) and rapidly (fast)-under normal lighting and in total darkness. Trunk angular velocity and finger velocity relative to the trunk were higher in the fast conditions but were not affected by the presence or absence of vision. Peak trunk velocity increased with increasing trunk rotation up to a maximum of 200 degrees /s. In slow movements, peak finger velocity relative to the trunk was smaller when trunk rotation was necessary to reach the targets. In fast movements, peak finger velocity was approximately 1.7 m/s for all targets. Finger trajectories were more curved when reaching movements involved substantial trunk rotation; however, the terminal errors and the maximal deviation of the trajectory from a straight line were comparable in slow and fast movements. This pattern indicates that the larger Coriolis, centripetal, and inertial interaction torques generated during rapid reaches were compensated by additional joint torques. Trajectory characteristics did not vary with the presence or absence of vision, indicating that visual feedback was unnecessary for anticipatory compensations. In all reaches involving trunk
Full Text Available Even though a growing body of research has shown that the processing of action language affects the planning and execution of motor acts, several aspects of this interaction are still hotly debated. The directionality (i.e. does understanding action-related language induce a facilitation or an interference with the corresponding action?, the time course, and the nature of the interaction (i.e. under what conditions does the phenomenon occur? are largely unclear. To further explore this topic we exploited a go/no-go paradigm in which healthy participants were required to perform arm reaching movements toward a target when verbs expressing either hand or foot actions were shown, and to refrain from moving when abstract verbs were presented. We found that reaction times (RT and percentages of errors increased when the verb involved the same effector used to give the response. This interference occurred very early, when the interval between verb presentation and the delivery of the go signal was 50 ms, and could be elicited until this delay was about 600 ms. In addition, RTs were faster when subjects used the right arm than when they used the left arm, suggesting that action-verb understanding is left-lateralized. Furthermore, when the color of the printed verb and not its meaning was the cue for movement execution the differences between RTs and error percentages between verb categories disappeared, unequivocally indicating that the phenomenon occurs only when the semantic content of a verb has to be retrieved. These results are compatible with the theory of embodied language, which hypothesizes that comprehending verbal descriptions of actions relies on an internal simulation of the sensory-motor experience of the action, and provide a new and detailed view of the interplay between action language and motor acts.
Mollazadeh, Mohsen; Aggarwal, Vikram; Thakor, Nitish V; Schieber, Marc H
A few kinematic synergies identified by principal component analysis (PCA) account for most of the variance in the coordinated joint rotations of the fingers and wrist used for a wide variety of hand movements. To examine the possibility that motor cortex might control the hand through such synergies, we collected simultaneous kinematic and neurophysiological data from monkeys performing a reach-to-grasp task. We used PCA, jPCA and isomap to extract kinematic synergies from 18 joint angles in the fingers and wrist and analyzed the relationships of both single-unit and multiunit spike recordings, as well as local field potentials (LFPs), to these synergies. For most spike recordings, the maximal absolute cross-correlations of firing rates were somewhat stronger with an individual joint angle than with any principal component (PC), any jPC or any isomap dimension. In decoding analyses, where spikes and LFP power in the 100- to 170-Hz band each provided better decoding than other LFP-based signals, the first PC was decoded as well as the best decoded joint angle. But the remaining PCs and jPCs were predicted with lower accuracy than individual joint angles. Although PCs, jPCs or isomap dimensions might provide a more parsimonious description of kinematics, our findings indicate that the kinematic synergies identified with these techniques are not represented in motor cortex more strongly than the original joint angles. We suggest that the motor cortex might act to sculpt the synergies generated by subcortical centers, superimposing an ability to individuate finger movements and adapt the hand to grasp a wide variety of objects.
Foroud, Afra; Whishaw, Ian Q
The purpose of this study was to adapt a universal language for human movement, Laban Movement Analysis (LMA), to capture the kinematic and non-kinematic aspects of movement in a reach-for-food task by subjects whose movements had been affected by stroke. Two control subjects, one stroke subject with internal capsule damage, and one subject with right posterior parietal stroke were video recorded while performing the reaching task. The movements of limb advancement, grasping the food, and limb withdrawal to place the food in the mouth, were notated using LMA. A scale, the Expressive Reaching Scale (ERS), was derived from the notation. All subjects completed the task; however, the stroke subjects displayed abnormalities in both the kinematic and non-kinematic aspects of movements during reaching with either limb. The most extensive impairments were in the contralateral-to-stroke limb and were most severe in the subject with internal capsule damage. The ERS rating scale may be a useful diagnosis and assessment tool.
Fuller, Jason R; Fung, Joyce; Côté, Julie N
Repetitive movements are common to many daily activities but often lead to the development of fatigue. We have previously shown that fatigue leads to changes in tridimensional spatial characteristics of the whole body. However, temporal aspects of these posture and movement adaptations have yet to be investigated. Healthy subjects (N = 14) performed a continuous reaching task by pointing between two targets placed at shoulder height, at 100 and 30% arm's length, anterior to the subject's midline until fatigue (assessed using the Borg CR-10 scale). Whole body kinematics and upper Trapezius EMG were recorded and analyzed at 1-min intervals to document the progression of fatigue on outcome variables. For all upper limb and postural variables analyzed, changes began to occur approximately midway to fatigue and were followed by an increase in Trapezius activity from baseline. Reach-to-reach variability of joint average positions and range of motion (ROM) increased in multiple directions for shoulder and elbow parameters. Reach-to-reach variability of the center-of-mass ROM also increased in several directions. Changes were also observed in within-movement inter-segmental timing. The peak velocities of elbow and endpoint occurred closer together in time during fatigue while the shoulder peak velocity occurrence showed a greater reach-to-reach variability. Our results suggest that the effects of fatigue on repetitive movement kinematics can be observed across three temporal dimensions of the task: (1) within individual movements, (2) from one movement to the next, and (3) as fatigue develops. Each observed change is discussed as a potential contributor to task-specific control strategies to prolong task performance.
Yeom, Hong Gi; Sic Kim, June; Chung, Chun Kee
Objective. Studies on the non-invasive brain-machine interface that controls prosthetic devices via movement intentions are at their very early stages. Here, we aimed to estimate three-dimensional arm movements using magnetoencephalography (MEG) signals with high accuracy. Approach. Whole-head MEG signals were acquired during three-dimensional reaching movements (center-out paradigm). For movement decoding, we selected 68 MEG channels in motor-related areas, which were band-pass filtered using four subfrequency bands (0.5-8, 9-22, 25-40 and 57-97 Hz). After the filtering, the signals were resampled, and 11 data points preceding the current data point were used as features for estimating velocity. Multiple linear regressions were used to estimate movement velocities. Movement trajectories were calculated by integrating estimated velocities. We evaluated our results by calculating correlation coefficients (r) between real and estimated velocities. Main results. Movement velocities could be estimated from the low-frequency MEG signals (0.5-8 Hz) with significant and considerably high accuracy (p 0.7). We also showed that preceding (60-140 ms) MEG signals are important to estimate current movement velocities and the intervals of brain signals of 200-300 ms are sufficient for movement estimation. Significance. These results imply that disabled people will be able to control prosthetic devices without surgery in the near future.
Vangheluwe, S.; Puttemans, V.; Wenderoth, N.; Baelen, M.G.M. van; Swinnen, S.P.
The present study examined whether the ability to dissociate bimanual limb movements following learning of a new coordination task (i.e. star-line drawing paradigm) can be generalised to different effector systems, as expressed by inter- and intralimb transfer. In Experiment 1, subjects practised th
Knips, Guido; Zibner, Stephan K U; Reimann, Hendrik; Schöner, Gregor
Reaching for objects and grasping them is a fundamental skill for any autonomous robot that interacts with its environment. Although this skill seems trivial to adults, who effortlessly pick up even objects they have never seen before, it is hard for other animals, for human infants, and for most autonomous robots. Any time during movement preparation and execution, human reaching movement are updated if the visual scene changes (with a delay of about 100 ms). The capability for online updating highlights how tightly perception, movement planning, and movement generation are integrated in humans. Here, we report on an effort to reproduce this tight integration in a neural dynamic process model of reaching and grasping that covers the complete path from visual perception to movement generation within a unified modeling framework, Dynamic Field Theory. All requisite processes are realized as time-continuous dynamical systems that model the evolution in time of neural population activation. Population level neural processes bring about the attentional selection of objects, the estimation of object shape and pose, and the mapping of pose parameters to suitable movement parameters. Once a target object has been selected, its pose parameters couple into the neural dynamics of movement generation so that changes of pose are propagated through the architecture to update the performed movement online. Implementing the neural architecture on an anthropomorphic robot arm equipped with a Kinect sensor, we evaluate the model by grasping wooden objects. Their size, shape, and pose are estimated from a neural model of scene perception that is based on feature fields. The sequential organization of a reach and grasp act emerges from a sequence of dynamic instabilities within a neural dynamics of behavioral organization, that effectively switches the neural controllers from one phase of the action to the next. Trajectory formation itself is driven by a dynamical systems version of
Knips, Guido; Zibner, Stephan K. U.; Reimann, Hendrik; Schöner, Gregor
Reaching for objects and grasping them is a fundamental skill for any autonomous robot that interacts with its environment. Although this skill seems trivial to adults, who effortlessly pick up even objects they have never seen before, it is hard for other animals, for human infants, and for most autonomous robots. Any time during movement preparation and execution, human reaching movement are updated if the visual scene changes (with a delay of about 100 ms). The capability for online updating highlights how tightly perception, movement planning, and movement generation are integrated in humans. Here, we report on an effort to reproduce this tight integration in a neural dynamic process model of reaching and grasping that covers the complete path from visual perception to movement generation within a unified modeling framework, Dynamic Field Theory. All requisite processes are realized as time-continuous dynamical systems that model the evolution in time of neural population activation. Population level neural processes bring about the attentional selection of objects, the estimation of object shape and pose, and the mapping of pose parameters to suitable movement parameters. Once a target object has been selected, its pose parameters couple into the neural dynamics of movement generation so that changes of pose are propagated through the architecture to update the performed movement online. Implementing the neural architecture on an anthropomorphic robot arm equipped with a Kinect sensor, we evaluate the model by grasping wooden objects. Their size, shape, and pose are estimated from a neural model of scene perception that is based on feature fields. The sequential organization of a reach and grasp act emerges from a sequence of dynamic instabilities within a neural dynamics of behavioral organization, that effectively switches the neural controllers from one phase of the action to the next. Trajectory formation itself is driven by a dynamical systems version of
Ibáñez, Jaime; Monge-Pereira, Esther; Molina-Rueda, Francisco; Serrano, J. I.; del Castillo, Maria D.; Cuesta-Gómez, Alicia; Carratalá-Tejada, María; Cano-de-la-Cuerda, Roberto; Alguacil-Diego, Isabel M.; Miangolarra-Page, Juan C.; Pons, Jose L.
Background: The association between motor-related cortical activity and peripheral stimulation with temporal precision has been proposed as a possible intervention to facilitate cortico-muscular pathways and thereby improve motor rehabilitation after stroke. Previous studies with patients have provided evidence of the possibility to implement brain-machine interface platforms able to decode motor intentions and use this information to trigger afferent stimulation and movement assistance. This study tests the use a low-latency movement intention detector to drive functional electrical stimulation assisting upper-limb reaching movements of patients with stroke. Methods: An eight-sessions intervention on the paretic arm was tested on four chronic stroke patients along 1 month. Patients' intentions to initiate reaching movements were decoded from electroencephalographic signals and used to trigger functional electrical stimulation that in turn assisted patients to do the task. The analysis of the patients' ability to interact with the intervention platform, the assessment of changes in patients' clinical scales and of the system usability and the kinematic analysis of the reaching movements before and after the intervention period were carried to study the potential impact of the intervention. Results: On average 66.3 ± 15.7% of trials (resting intervals followed by self-initiated movements) were correctly classified with the decoder of motor intentions. The average detection latency (with respect to the movement onsets estimated with gyroscopes) was 112 ± 278 ms. The Fügl-Meyer index upper extremity increased 11.5 ± 5.5 points with the intervention. The stroke impact scale also increased. In line with changes in clinical scales, kinematics of reaching movements showed a trend toward lower compensatory mechanisms. Patients' assessment of the therapy reflected their acceptance of the proposed intervention protocol. Conclusions: According to results obtained here
Julià L Amengual
Full Text Available The study of the movement related brain potentials (MRPBs needs accurate technical approaches to disentangle the specific patterns of bran activity during the preparation and execution of movements. During the last forty years, synchronizing the electromiographic activation (EMG of the muscle with the electrophysiological recordings (EEG has been commonly ussed for these purposes. However, new clinical approaches in the study of motor diseases and rehabilitation suggest the demand of new paradigms that might go further into the study of the brain activity associated with the kinematics of movement. As a response to this call, we have used a 3-D hand tracking system with the aim to record continuously the position of an ultrasonic sender located on the hand during the performance of multi-joint self-pace movements. We synchronized the time-series of position of velocity of the sender with the EEG recordings, obtaining specific patterns of brain activity as a function of the fluctuations of the kinematics during the natural movement performance. Additionally, the distribution of the brain activity during the preparation and execution phases of movement was similar that reported previously using the EMG, suggesting the validity of our technique. We claim that this paradigm could be usable in patients because of its simplicity and the potential knowledge that can be extracted from clinical protocols.
Full Text Available Grasping an object involves shaping the hand and fingers in relation to the object's physical properties. Following object contact, it also requires a fine adjustment of grasp forces for secure manipulation. Earlier studies suggest that the control of hand shaping and grasp force involve partially segregated motor cortical networks. However, it is still unclear how information originating from these networks is processed and integrated. We addressed this issue by analyzing massively parallel signals from population measures (local field potentials, LFPs and single neuron spiking activities recorded simultaneously during a delayed reach-to-grasp task, by using a 100 electrode array chronically implanted in monkey motor cortex. Motor cortical LFPs exhibit a large multi-component movement-related potential (MRP around movement onset. Here, we show that the peak amplitude of each MRP component and its latency with respect to movement onset vary along the cortical surface covered by the array. Using a comparative mapping approach, we suggest that the spatio-temporal structure of the MRP reflects the complex physical properties of the reach-to-grasp movement. In addition, we explored how the spatio-temporal structure of the MRP relates to two other measures of neuronal activity: the temporal profile of single neuron spiking activity at each electrode site and the somatosensory receptive field properties of single neuron activities. We observe that the spatial representations of LFP and spiking activities overlap extensively and relate to the spatial distribution of proximal and distal representations of the upper limb. Altogether, these data show that, in motor cortex, a precise spatio-temporal pattern of activation is involved for the control of reach-to-grasp movements and provide some new insight about the functional organization of motor cortex during reaching and object manipulation.
Riehle, Alexa; Wirtssohn, Sarah; Grün, Sonja; Brochier, Thomas
Grasping an object involves shaping the hand and fingers in relation to the object's physical properties. Following object contact, it also requires a fine adjustment of grasp forces for secure manipulation. Earlier studies suggest that the control of hand shaping and grasp force involve partially segregated motor cortical networks. However, it is still unclear how information originating from these networks is processed and integrated. We addressed this issue by analyzing massively parallel signals from population measures (local field potentials, LFPs) and single neuron spiking activities recorded simultaneously during a delayed reach-to-grasp task, by using a 100-electrode array chronically implanted in monkey motor cortex. Motor cortical LFPs exhibit a large multi-component movement-related potential (MRP) around movement onset. Here, we show that the peak amplitude of each MRP component and its latency with respect to movement onset vary along the cortical surface covered by the array. Using a comparative mapping approach, we suggest that the spatio-temporal structure of the MRP reflects the complex physical properties of the reach-to-grasp movement. In addition, we explored how the spatio-temporal structure of the MRP relates to two other measures of neuronal activity: the temporal profile of single neuron spiking activity at each electrode site and the somatosensory receptive field properties of single neuron activities. We observe that the spatial representations of LFP and spiking activities overlap extensively and relate to the spatial distribution of proximal and distal representations of the upper limb. Altogether, these data show that, in motor cortex, a precise spatio-temporal pattern of activation is involved for the control of reach-to-grasp movements and provide some new insight about the functional organization of motor cortex during reaching and object manipulation.
Verheyden, G.; Duijnhoven, H.J.R. van; Burnett, M.; Littlewood, J.; Kunkel, D.; Ashburn, A.M.
BACKGROUND: Sideways reaching with the unaffected arm while seated is a component of everyday activities and can be a challenging task early after stroke. Kinematic analysis of a lateral reach task may provide potential rehabilitation strategies. OBJECTIVE: The authors examined the difference betwee
Skurvidas, A; Mickevichiene, D; Cesnavichiene, V; Gutnik, B; Nash, D
In labor and sport physiology a great deal of interest concerns the conceptual model of governance of both rapid and precise target-directed movements. Widely known in the theory of motor control, Fitts' paradigm determines the time of motion, calculated from the distance to the target and the diameter of the target. However this paradigm does not take into account the time of preparation for movement, which can have a significant impact on accuracy. In addition, the literature highlights little evidence of temporal and spatial asymmetry in the production of fast and accurate movements. The aim of our work was to investigate the influence of the duration of the preparatory phase (reaction time - T(R)) and duration of protractile motion of the arm (T(M)) on the speed and accuracy of movement. Also, the in-dividual asymmetry of the temporal characteristics and accuracy of performance of movements were studied. We measured three aspects of translational motion of the arm to the computerized target: reaction time (T(R), s), time of motion of the arm (T(M), s), and error in the achievement of the target (deltaL, mm). The group of participants consisted of 12 healthy, right-handed, untrained girls, each of whom completed 5 series of 10 discrete movements by each of the left and right arms. Mathematical analysis of the results revealed the existence of five models of performance. Each model was represented in the participant's performance with different probability. The combination of high speed and high precision when the arm moved towards the target was found only in model 5, which combines a long period of preparation for the movement (T(R)) and a short time of motion (T(M)). The probability of its occurrence in the untrained subjects was very low (2-3%). We suggest that it may be possible to develop special methods of training, geared towards the ability to increase the probability of appearance of this model. Asymmetry of motor action appeared clearly evident only in
Nguyen, Hung P; Dingwell, Jonathan B
Determining how the human nervous system contends with neuro-motor noise is vital to understanding how humans achieve accurate goal-directed movements. Experimentally, people learning skilled tasks tend to reduce variability in distal joint movements more than in proximal joint movements. This suggests that they might be imposing greater control over distal joints than proximal joints. However, the reasons for this remain unclear, largely because it is not experimentally possible to directly manipulate either the noise or the control at each joint independently. Therefore, this study used a 2 degree-of-freedom torque driven arm model to determine how different combinations of noise and/or control independently applied at each joint affected the reaching accuracy and the total work required to make the movement. Signal-dependent noise was simultaneously and independently added to the shoulder and elbow torques to induce endpoint errors during planar reaching. Feedback control was then applied, independently and jointly, at each joint to reduce endpoint error due to the added neuromuscular noise. Movement direction and the inertia distribution along the arm were varied to quantify how these biomechanical variations affected the system performance. Endpoint error and total net work were computed as dependent measures. When each joint was independently subjected to noise in the absence of control, endpoint errors were more sensitive to distal (elbow) noise than to proximal (shoulder) noise for nearly all combinations of reaching direction and inertia ratio. The effects of distal noise on endpoint errors were more pronounced when inertia was distributed more toward the forearm. In contrast, the total net work decreased as mass was shifted to the upper arm for reaching movements in all directions. When noise was present at both joints and joint control was implemented, controlling the distal joint alone reduced endpoint errors more than controlling the proximal joint
Issen, Laurel A; Knill, David C
When reaching for objects, humans make saccades to fixate the object at or near the time the hand begins to move. In order to address whether the CNS relies on a common representation of target positions to plan both saccades and hand movements, we quantified the contributions of visual short-term memory (VSTM) to hand and eye movements executed during the same coordinated actions. Subjects performed a sequential movement task in which they picked up one of two objects on the right side of a virtual display (the "weapon"), moved it to the left side of the display (to a "reloading station") and then moved it back to the right side to hit the other object (the target). On some trials, the target was perturbed by 1° of visual angle while subjects moved the weapon to the reloading station. Although subjects did not notice the change, the original position of the target, encoded in VSTM, influenced the motor plans for both the hand and the eye back to the target. Memory influenced motor plans for distant targets more than for near targets, indicating that sensorimotor planning is sensitive to the reliability of available information; however, memory had a larger influence on hand movements than on eye movements. This suggests that spatial planning for coordinated saccades and hand movements are dissociated at the level of processing at which online visual information is integrated with information in short-term memory.
Sakurada, Takeshi; Ito, Koji; Gomi, Hiroaki
Although strong motor coordination in intrinsic muscle coordinates has frequently been reported for bimanual movements, coordination in extrinsic visual coordinates is also crucial in various bimanual tasks. To explore the bimanual coordination mechanisms in terms of the frame of reference, here we characterized implicit bilateral interactions in visuomotor tasks. Visual perturbations (finger-cursor gain change) were applied while participants performed a rhythmic tracking task with both index fingers under an in-phase or anti-phase relationship in extrinsic coordinates. When they corrected the right finger's amplitude, the left finger's amplitude unintentionally also changed [motor interference (MI)], despite the instruction to keep its amplitude constant. Notably, we observed two specificities: one was large MI and low relative-phase variability (PV) under the intrinsic in-phase condition, and the other was large MI and high PV under the extrinsic in-phase condition. Additionally, using a multiple-interaction model, we successfully decomposed MI into intrinsic components caused by motor correction and extrinsic components caused by visual-cursor mismatch of the right finger's movements. This analysis revealed that the central nervous system facilitates MI by combining intrinsic and extrinsic components in the condition with in-phases in both intrinsic and extrinsic coordinates, and that under-additivity of the effects is explained by the brain's preference for the intrinsic interaction over extrinsic interaction. In contrast, the PV was significantly correlated with the intrinsic component, suggesting that the intrinsic interaction dominantly contributed to bimanual movement stabilization. The inconsistent features of MI and PV suggest that the central nervous system regulates multiple levels of bilateral interactions for various bimanual tasks.
Full Text Available In Motor Neglect (MN syndrome, a specific impairment in non-congruent bimanual movements has been described. In the present case-control study, we investigated the neuro-functional correlates of this behavioral deficit. Two right-brain-damaged patients, one with (MN+ and one without (MN- MN, were evaluated by means of functional Magnetic Resonance Imaging (fMRI in a bimanual Circles-Lines paradigm. Patients were requested to perform right-hand movements (lines-drawing and, simultaneously, congruent (lines-drawing or non-congruent (circles-drawing left-hand movements. In the behavioral task, MN- patient showed a bimanual-coupling-effect, while MN+ patient did not. The fMRI study showed that in MN-, a fronto-parietal network, mainly involving the pre-supplementary motor area (pre-SMA and the posterior parietal cortex (PPC, was significantly more active in non-congruent than in congruent conditions, as previously shown in healthy subjects. On the contrary, MN+ patient showed an opposite pattern of activation both in pre-SMA and in PPC. Within this fronto-parietal network, the pre-SMA is supposed to exert an inhibitory influence on the default coupling of homologous muscles, thus allowing the execution of non-congruent movements. In MN syndrome, the described abnormal pre-SMA activity supports the hypothesis that a failure to inhibit ipsilesional motor programs might determine a specific impairment of non-congruent movements.
The neurophysiology of the monkey and human brain shows that transformation of visuomotor coordinates is related to the activation of a distributed and complex population of parietal, premotor and motor neurons. We can think about these circuits like different cortical areas activated in different times during reaching and grasping planning and execution, with different relations and communications among them. In this theoretic field, my PhD project was aimed at investigating the organizat...
Full Text Available To better define the neural networks related to preparation of reaching, we applied transcranial magnetic stimulation (TMS to the lateral parietal and frontal cortex. TMS did not evoke effects closely related to preparation of reaching, suggesting that neural networks already identified by our group are not larger than previously thought. We also replicated previous TMS/EEG data by applying TMS to the parietal cortex: new analyses were performed to better support reliability of already reported findings (Zanon et al., 2010; Brain Topography 22, 307-317. We showed the existence of neural circuits ranging from posterior to frontal regions of the brain after the stimulation of parietal cortex, supporting the idea of strong connections among these areas and suggesting their possible temporal dynamic. Connection with ventral stream was confirmed.The present work helps to define those areas which are involved in preparation of natural reaching in humans. They correspond to parieto-occipital, parietal and premotor medial regions of the left hemisphere, i.e. the contralateral one with respect to the moving hand, as suggested by previous studies. Behavioral data support the existence of a discrete stream involved in reaching. Besides the serial flow of activation from posterior to anterior direction, a parallel elaboration of information among parietal and premotor areas seems also to exist. Present cortico-cortical interactions (TMS/EEG experiment show propagation of activity to frontal, temporal, parietal and more posterior regions, exhibiting distributed communication among various areas in the brain.The neural system highlighted by TMS/EEG experiments is wider with respect to the one disclosed by the TMS behavioral approach. Further studies are needed to unravel this paucity of overlap. Moreover, the understanding of these mechanisms is crucial for the comprehension of response inhibition and changes in prepared actions, which are common behaviors in
Chu, Virginia Way Tong; Sanger, Terence David
Practice of movement in virtual-reality and other artificially altered environments has been proposed as a method for rehabilitation following neurological injury and for training new skills in healthy humans. For such training to be useful, there must be transfer of learning from the artificial environment to the performance of desired skills in the natural environment. Therefore an important assumption of such methods is that practice in the altered environment engages the same learning and plasticity mechanisms that are required for skill performance in the natural environment. We test the hypothesis that transfer of learning may fail because the learning and plasticity mechanism that adapts to the altered environment is different from the learning mechanism required for improvement of motor skill. In this paper, we propose that a model that separates skill learning and environmental adaptation is necessary to explain the learning and aftereffects that are observed in virtual reality experiments. In particular, we studied the condition where practice in the altered environment should lead to correct skill performance in the original environment. Our 2-mechanism model predicts that aftereffects will still be observed when returning to the original environment, indicating a lack of skill transfer from the artificial environment to the original environment. To illustrate the model prediction, we tested 10 healthy participants on the interaction between a simple overlearned motor skill (straight hand movements to targets in different directions) and an artificially altered visuomotor environment (rotation of visual feedback of the results of movement). As predicted by the models, participants show adaptation to the altered environment and after-effects on return to the baseline environment even when practice in the altered environment should have led to correct skill performance. The presence of aftereffect under all conditions that involved changes in
Friel, Kathleen M; Kuo, Hsing-Ching; Fuller, Jason; Ferre, Claudio L; Brandão, Marina; Carmel, Jason B; Bleyenheuft, Yannick; Gowatsky, Jaimie L; Stanford, Arielle D; Rowny, Stefan B; Luber, Bruce; Bassi, Bruce; Murphy, David L K; Lisanby, Sarah H; Gordon, Andrew M
Background Intensive bimanual therapy can improve hand function in children with unilateral spastic cerebral palsy (USCP). We compared the effects of structured bimanual skill training versus unstructured bimanual practice on motor outcomes and motor map plasticity in children with USCP. Objective We hypothesized that structured skill training would produce greater motor map plasticity than unstructured practice. Methods Twenty children with USCP (average age 9.5; 12 males) received therapy in a day camp setting, 6 h/day, 5 days/week, for 3 weeks. In structured skill training (n = 10), children performed progressively more difficult movements and practiced functional goals. In unstructured practice (n = 10), children engaged in bimanual activities but did not practice skillful movements or functional goals. We used the Assisting Hand Assessment (AHA), Jebsen-Taylor Test of Hand Function (JTTHF), and Canadian Occupational Performance Measure (COPM) to measure hand function. We used single-pulse transcranial magnetic stimulation to map the representation of first dorsal interosseous and flexor carpi radialis muscles bilaterally. Results Both groups showed significant improvements in bimanual hand use (AHA; P < .05) and hand dexterity (JTTHF; P < .001). However, only the structured skill group showed increases in the size of the affected hand motor map and amplitudes of motor evoked potentials (P < .01). Most children who showed the most functional improvements (COPM) had the largest changes in map size. Conclusions These findings uncover a dichotomy of plasticity: the unstructured practice group improved hand function but did not show changes in motor maps. Skill training is important for driving motor cortex plasticity in children with USCP.
Full Text Available The theory of embodied language states that language comprehension relies on an internal reenactment of the sensorimotor experience associated with the processed word or sentence. Most evidence in support of this hypothesis had been collected using linguistic material without any emotional connotation. For instance, it had been shown that processing of arm-related verbs, but not of those leg-related verbs, affects the planning and execution of reaching movements; however, at present it is unknown whether this effect is further modulated by verbs evoking an emotional experience. Showing such a modulation might shed light on a very debated issue, i.e. the way in which the emotional meaning of a word is processed. To this end, we assessed whether processing arm/hand-related verbs describing actions with negative connotations (e.g. to stab affects reaching movements differently from arm/hand-related verbs describing actions with neutral connotation (e.g. to comb. We exploited a go/no-go paradigm in which healthy participants were required to perform arm-reaching movements toward a target when verbs expressing emotional hand actions, neutral hand actions or foot actions were shown, and to refrain from moving when no-effector-related verbs were presented. Reaction times and percentages of errors increased when the verb involved the same effector as used to give the response. However, we also found that the size of this interference decreased when the arm/hand-related verbs had a negative emotional connotation. Crucially, we show that such modulation only occurred when the verb semantics had to be retrieved. These results suggest that the comprehension of negatively valenced verbs might require the simultaneous reenactment of the neural circuitry associated with the processing of the emotion evoked by their meaning and of the neural circuitry associated with their motor features.
Spadacenta, Silvia; Gallese, Vittorio; Fragola, Michele; Mirabella, Giovanni
The theory of embodied language states that language comprehension relies on an internal reenactment of the sensorimotor experience associated with the processed word or sentence. Most evidence in support of this hypothesis had been collected using linguistic material without any emotional connotation. For instance, it had been shown that processing of arm-related verbs, but not of those leg-related verbs, affects the planning and execution of reaching movements; however, at present it is unknown whether this effect is further modulated by verbs evoking an emotional experience. Showing such a modulation might shed light on a very debated issue, i.e. the way in which the emotional meaning of a word is processed. To this end, we assessed whether processing arm/hand-related verbs describing actions with negative connotations (e.g. to stab) affects reaching movements differently from arm/hand-related verbs describing actions with neutral connotation (e.g. to comb). We exploited a go/no-go paradigm in which healthy participants were required to perform arm-reaching movements toward a target when verbs expressing emotional hand actions, neutral hand actions or foot actions were shown, and to refrain from moving when no-effector-related verbs were presented. Reaction times and percentages of errors increased when the verb involved the same effector as used to give the response. However, we also found that the size of this interference decreased when the arm/hand-related verbs had a negative emotional connotation. Crucially, we show that such modulation only occurred when the verb semantics had to be retrieved. These results suggest that the comprehension of negatively valenced verbs might require the simultaneous reenactment of the neural circuitry associated with the processing of the emotion evoked by their meaning and of the neural circuitry associated with their motor features.
Tanaka, Hirokazu; Sejnowski, Terrence J
The brain processes sensory and motor information in a wide range of coordinate systems, ranging from retinal coordinates in vision to body-centered coordinates in areas that control musculature. Here we focus on the coordinate system used in the motor cortex to guide actions and examine physiological and psychophysical evidence for an allocentric reference frame based on spatial coordinates. When the equations of motion governing reaching dynamics are expressed as spatial vectors, each term is a vector cross product between a limb-segment position and a velocity or acceleration. We extend this computational framework to motor adaptation, in which the cross-product terms form adaptive bases for canceling imposed perturbations. Coefficients of the velocity- and acceleration-dependent cross products are assumed to undergo plastic changes to compensate the force-field or visuomotor perturbations. Consistent with experimental findings, each of the cross products had a distinct reference frame, which predicted how an acquired remapping generalized to untrained location in the workspace. In response to force field or visual rotation, mainly the coefficients of the velocity- or acceleration-dependent cross products adapted, leading to transfer in an intrinsic or extrinsic reference frame, respectively. The model further predicted that remapping of visuomotor rotation should under- or overgeneralize in a distal or proximal workspace. The cross-product bases can explain the distinct patterns of generalization in visuomotor and force-field adaptation in a unified way, showing that kinematic and dynamic motor adaptation need not arise through separate neural substrates.
Shirzad, Navid; Van der Loos, H F Machiel
The notion of an optimal difficulty during practice has been articulated in many areas of cognitive psychology: flow theory, the challenge point framework, and desirable difficulties. Delivering exercises at a participant's desired difficulty has the potential to improve both motor learning and users' engagement in therapy. Motivation and engagement are among the contributing factors to the success of exercise programs. The authors previously demonstrated that error amplification can be used to introduce levels of challenge into a robotic reaching task, and that machine-learning algorithms can dynamically adjust difficulty to the desired level with 85% accuracy. Building on these findings, we present the results of a proof-of-concept study investigating the impacts of practicing under desirable difficulty conditions. A control condition with a predefined random order for difficulty levels was deemed more suitable for this study (compared to constant or continuously increasing difficulty). By practicing the task at their desirable difficulties, participants in the experimental group perceived their performance at a significantly higher level and reported lower required effort to complete the task, in comparison to a control group. Moreover, based on self-reports, participants in the experimental group were willing, on average, to continue the training session for 4.6 more training blocks (∼45 min) compared to the control group's average. This study demonstrates the efficiency of delivering the exercises at the user's desired difficulty level to improve the user's engagement in exercise tasks. Future work will focus on clinical feasibility of this approach in increasing stroke survivors' engagement in their therapy programs.
Goto, Kotaro; Hoshi, Yoko; Sata, Masashi; Kawahara, Masatoshi; Takahashi, Makoto; Murohashi, Harumitsu
To elucidate the role of the prefrontal cortex in cognitive control of reaching movements, by multichannel near-infrared spectroscopy we examine changes in oxygenated hemoglobin (oxy-Hb) as an indicator of changes in regional cerebral blood flow in the bilateral dorsolateral (DLPFC), ventrolateral prefrontal cortex (VLPFC), and frontopolar cortex (FPC) during a reaching task with normal visual feedback (a consistent task) and a reaching task with flipped horizontal visual feedback (an inconsistent task). Subjects first perform 12 trials of the consistent task, and then perform six blocks of the inconsistent task, each of which consists of six trials. During the consistent task, oxy-Hb is increased only in the right VLPFC. During the first block of the inconsistent task, increases in oxy-Hb are observed in the bilateral DLPFC and the right VLPFC, whereas the increased oxy-Hb was gradually reduced as the block proceeded, which was accompanied by an improvement in the task performance. Eventually, there were no differences in the degree of change in oxy-Hb between the consistent and inconsistent tasks in the DLPFC and VLPFC. These findings suggest that the DLPFC is engaged in higher order cognitive control, while the right VLPFC is engaged in both higher and lower order cognitive controls.
Stacey L. Gorniak
Full Text Available We investigated the kinetic features of manual dexterity and fine motor control during a task that resembles an activity of daily living in 30 persons with relapsing-remitting multiple sclerosis (PwMS. Specifically, a novel two-transducer system was used to measure time and grip-load forces during a bimanual task that is similar to opening and closing a jar. We hypothesized that PwMS would have increased grip force production, deteriorations in kinetic timing, and preserved grip-load coupling indices compared to healthy controls (i.e., young and older adults. Increased grip force production and deterioration in timing indices were confirmed in PwMS. Abnormal grip-load coupling was exhibited by PwMS, in contrast to healthy participants. The correlation between task time and self-reported disability scores suggests that objective measurement of impaired upper-extremity movements relates to perception of overall function.
Saga, Yosuke; Hashimoto, Masashi; Tremblay, Léon; Tanji, Jun; Hoshi, Eiji
The dorsal aspect of the globus pallidus (GP) communicates with the prefrontal cortex and higher-order motor areas, indicating that it plays a role in goal-directed behavior. We examined the involvement of dorsal GP neurons in behavioral goal monitoring and maintenance, essential components of executive function. We trained two macaque monkeys to choose a reach target based on relative target position in a spatial goal task or a target shape in an object-goal task. The monkeys were trained to continue to choose a certain behavioral goal when reward volume was constant and to switch the goals when the volume began to decrease. Because the judgment for the next goal was made in the absence of visual signals, the monkeys were required to monitor and maintain the chosen goals during the reaching movement. We obtained three major findings. (1) GP neurons reflected more of the relative spatial position than the shape of the reaching target during the spatial goal task. During the object-goal task, the shape of the reaching object was represented more than the relative position. (2) The selectivity of individual neurons for the relative position was enhanced during the spatial goal task, whereas the object-shape selectivity was enhanced during the object-goal task. (3) When the monkeys switched the goals, the selectivity for either the position or shape also switched. Together, these findings suggest that the dorsal GP is involved in behavioral goal monitoring and maintenance during execution of goal-oriented actions, presumably in collaboration with the prefrontal cortex.
Schepens, Bénédicte; Drew, Trevor
We have addressed the nature of the postural control signals contained within the discharge activity of neurons in the pontomedullary reticular formation, including reticulospinal neurons, during a reaching task in the cat. We recorded the activity of 142 neurons during ipsilateral reaching movements that required anticipatory postural adjustments (APAs) in the supporting limbs to maintain equilibrium. Discharge activity in 82/142 (58%) neurons was significantly increased before the onset of the reach. Most of these neurons discharged either in a phasic (22/82), tonic (10/82), or phasic/tonic (41/82) pattern. In each of these 3 groups, the onset of the discharge activity in some neurons was temporally related either to the go signal or to the onset of the movement. In many neurons, one component of the discharge sequence was better related to the go signal and another to the onset of the movement. Based on our previous behavioral study during the same task, we suggest that reticular neurons in which the discharge activity is better related to the go signal contribute to the initiation of the APAs that precede the movement. Neurons in which the discharge activity is better related to the movement signal might contribute to the initiation of the movement and to the production of the postural responses that accompany that movement. Together our results suggest the existence of neurons that signal posture and movement independently and others that encode a convergent signal that contributes to the control of both posture and movement.
Jung, Patrick; Klein, Johannes C; Wibral, Michael; Hoechstetter, Karsten; Bliem, Barbara; Lu, Ming-Kuei; Wahl, Mathias; Ziemann, Ulf
Little is known about the spatiotemporal dynamics of cortical responses that integrate slightly asynchronous somatosensory inputs from both hands. This study aimed to clarify the timing and magnitude of interhemispheric interactions during early integration of bimanual somatosensory information in different somatosensory regions and their relevance for bimanual object manipulation and exploration. Using multi-fiber probabilistic diffusion tractography and MEG source analysis of conditioning-test (C-T) median nerve somatosensory evoked fields in healthy human subjects, we sought to extract measures of structural and effective callosal connectivity between different somatosensory cortical regions and correlated them with bimanual tactile task performance. Neuromagnetic responses were found in major somatosensory regions, i.e., primary somatosensory cortex SI, secondary somatosensory cortex SII, posterior parietal cortex, and premotor cortex. Contralateral to the test stimulus, SII activity was maximally suppressed by 51% at C-T intervals of 40 and 60 ms. This interhemispheric inhibition of the contralateral SII source activity correlated directly and topographically specifically with the fractional anisotropy of callosal fibers interconnecting SII. Thus, the putative pathway that mediated inhibitory interhemispheric interactions in SII was a transcallosal route from ipsilateral to contralateral SII. Moreover, interhemispheric inhibition of SII source activity correlated directly with bimanual tactile task performance. These findings were exclusive to SII. Our data suggest that early interhemispheric somatosensory integration primarily occurs in SII, is mediated by callosal fibers that interconnect homologous SII areas, and has behavioral importance for bimanual object manipulation and exploration.
Garbarini, Francesca; Rabuffetti, Marco; Piedimonte, Alessandro; Pia, Lorenzo; Ferrarin, Maurizio; Frassinetti, Francesca; Gindri, Patrizia; Cantagallo, Anna; Driver, Jon; Berti, Anna
Selective neurological impairments can shed light on different aspects of motor cognition. Brain-damaged patients with anosognosia for hemiplegia deny their motor deficit and believe they can still move the paralysed limb. Here we study, for the first time, if the anomalous subjective experience that their affected hand can still move, may have objective consequences that constrain movement execution with the opposite, intact hand. Using a bimanual motor task, in which anosognosic patients were asked to simultaneously trace out lines with their unaffected hand and circles with their paralysed hand, we found that the trajectories of the intact hand were influenced by the requested movement of the paralysed hand, with the intact hand tending to assume an oval trajectory (bimanual coupling effect). This effect was comparable to that of a group of healthy subjects who actually moved both hands. By contrast, brain-damaged patients with motor neglect or actual hemiplegia but no anosognosia did not show this bimanual constraint. We suggest that anosognosic patients may have intact motor intentionality and planning for the plegic hand. Rather than being merely an inexplicable confabulation, anosognosia for the plegic hand can produce objective constraints on what the intact hand does.
Lin, Chueh-Ho; Chou, Li-Wei; Wei, Shun-Hwa; Lieu, Fu-Kong; Chiang, Shang-Lin; Sung, Wen-Hsu
Degeneration in the neuromuscular system due to aging can affect daily activities that need to be controlled by bimanual coordination with both hands. However, little is known about the influence of aging on grip strength and bimanual coordination control between hands. The purpose of this study was to investigate the influence of aging on the maximum grip force output and capacity of coordination control of two hands. Ten healthy elderly and 21 young adults were recruited and asked to execute maximum grip force tests and bimanual coordination control tasks with reciprocal grasping, holding, and releasing of a dynamometer with both hands at three target force levels (10, 20 and 40% maximal voluntary contraction, MVC). Compared with the young group, the maximum grip force of the hands of the elderly group was significantly lower by 77.5% (pelderly adults also displayed a significantly longer alternating time control in the dominant to non-dominant and non-dominant to dominant hands at the 20% MVC target force level (pcoordination control of two hands, which may lead to difficulty with the execution of daily activities requiring both hands.
Helene M Sisti
Full Text Available The acquisition of a new bimanual skill depends on several motor coordination constraints. To date, coordination constraints have often been tested relatively independently of one another, particularly with respect to isofrequency and multifrequency rhythms. Here, we used a new paradigm to test the interaction of multiple coordination constraints. Coordination constraints that were tested included temporal complexity, directionality, muscle grouping, and hand dominance. Twenty-two healthy young adults performed a bimanual dial rotation task that required left and right hand coordination to track a moving target on a computer monitor. Two groups were compared, either with or without four days of practice with augmented visual feedback. Four directional patterns were tested such that both hands moved either rightward (clockwise, leftward (counterclockwise, inward or outward relative to each other. Seven frequency ratios (3∶1, 2∶1, 3∶2, 1∶1, 2∶3. 1∶2, 1∶3 between the left and right hand were introduced. As expected, isofrequency patterns (1∶1 were performed more successfully than multifrequency patterns (non 1∶1. In addition, performance was more accurate when participants were required to move faster with the dominant right hand (1∶3, 1∶2 and 2∶3 than with the non-dominant left hand (3∶1, 2∶1, 3∶2. Interestingly, performance deteriorated as the relative angular velocity between the two hands increased, regardless of whether the required frequency ratio was an integer or non-integer. This contrasted with previous finger tapping research where the integer ratios generally led to less error than the non-integer ratios. We suggest that this is due to the different movement topologies that are required of each paradigm. Overall, we found that this visuomotor task was useful for testing the interaction of multiple coordination constraints as well as the release from these constraints with practice in the presence of
Sacrey, Lori-Ann R; Karl, Jenni M; Whishaw, Ian Q
The reach-to-eat movement is a natural act in which an object or food item is grasped and brought to the mouth. It is one of the earliest forelimb behaviours displayed by human infants, who bring almost all grasped objects to the mouth, and is used daily by adults. In adults, there is a tight coupling between visual attention and the advance phase of the reach-to-eat movement. The target is visually engaged just as hand advance is initiated and visually disengaged just as the target is grasped. This coupling of vision and hand advance suggests that advance is mediated by visual attention and withdrawal by somatosensation. The present study examined when the tight coupling between visual attention and the advance phase of the movement develops in infancy. In a longitudinal study, eight infants, aged 6-12 months, and 20 adults reached for familiar inanimate objects and food items. Visual gaze, hand movement and hand accuracy were measured using frame-by-frame video scoring and 2D kinematic analysis. The study found that the youngest infants (6-8 months) visually engaged the target well before initiating a reaching movement and continued to fixate on the target after it was grasped and as it was brought to the mouth. Between 10 and 12 months of age, infants began to visually engage the target just as the reaching movement was initiated and visually disengaged the target as it was grasped, as did the adults. Over the same developmental time period, the infants developed rotatory hand shaping movements, precision grasping, and improved targeting accuracy both for grasping the object and placing it into the mouth. The results suggest that visual guidance of advance and somatosensory guidance of withdrawal develop together and in concert with hand movement ability and skill.
Serrien, Deborah J.; Sovijärvi-Spapé, Michiel M.; Rana, Gita
Manual dexterity is known to gradually progress with developmental age. In this study, we evaluate the performance of unimanual and bimanual actions under perturbed and unperturbed conditions in children between 4 and 10 years of age. Behavior was assessed by means of trajectory measurements and degree of bimanual coupling. The results showed that…
Matthieu P. Boisgontier
Full Text Available Despite the intensive investigation of bimanual coordination, it remains unclear how directing vision toward either limb influences performance, and whether this influence is affected by age. To examine these questions, we assessed the performance of young and older adults on a bimanual tracking task in which they matched motor-driven movements of their right hand (passive limb with their left hand (active limb according to in-phase and anti-phase patterns. Performance in six visual conditions involving central vision, and/or peripheral vision of the active and/or passive limb was compared to performance in a no vision condition. Results indicated that directing central vision to the active limb consistently impaired performance, with higher impairment in older than young adults. Conversely, directing central vision to the passive limb improved performance in young adults, but less consistently in older adults. In conditions involving central vision of one limb and peripheral vision of the other limb, similar effects were found to those for conditions involving central vision of one limb only. Peripheral vision alone resulted in similar or impaired performance compared to the no vision condition. These results indicate that the locus of visual attention is critical for bimanual motor control in young and older adults, with older adults being either more impaired or less able to benefit from a given visual condition.
Chiou, Shiau-Chuen; Chang, Erik Chihhung
Previous studies have shown that bimanual coordination learning is more resistant to the removal of augmented feedback when acquired with auditory than with visual channel. However, it is unclear whether this differential "guidance effect" between feedback modalities is due to enhanced sensorimotor integration via the non-dominant auditory channel or strengthened linkage to kinesthetic information under rhythmic input. The current study aimed to examine how modalities (visual vs. auditory) and information types (continuous visuospatial vs. discrete rhythmic) of concurrent augmented feedback influence bimanual coordination learning. Participants either learned a 90°-out-of-phase pattern for three consecutive days with Lissajous feedback indicating the integrated position of both arms, or with visual or auditory rhythmic feedback reflecting the relative timing of the movement. The results showed diverse performance change after practice when the feedback was removed between Lissajous and the other two rhythmic groups, indicating that the guidance effect may be modulated by the type of information provided during practice. Moreover, significant performance improvement in the dual-task condition where the irregular rhythm counting task was applied as a secondary task also suggested that lower involvement of conscious control may result in better performance in bimanual coordination.
Full Text Available Although bimanual finger coordination is known to decline with aging, it still remains unclear how exactly the neural substrates underlying the coordination differ between young and elderly adults. The present study focused on: (1 characterization of the functional connectivity within the motor association cortex which is required for successful bimanual finger coordination, and (2 to elucidate upon its age-related decline. To address these objectives, we utilized functional magnetic resonance imaging (fMRI in combination with structural equation modeling (SEM. This allowed us to compare functional connectivity models between young and elderly age groups during a visually guided bimanual finger movement task using both stable in-phase and complex anti-phase modes. Our SEM exploration of functional connectivity revealed significant age-related differences in connections surrounding the PMd in the dominant hemisphere. In the young group who generally displayed accurate behavior, the SEM model for the anti-phase mode exhibited significant connections from the dominant PMd to the non-dominant SPL, and from the dominant PMd to the dominant S1. However, the model for the elderly group’s anti-phase mode in which task performance dropped, did not exhibit significant connections within the aforementioned regions. These results suggest that: (1 the dominant PMd acts as an intermediary to invoke intense intra- and inter-hemispheric connectivity with distant regions among the higher motor areas including the dominant S1 and the non-dominant SPL in order to achieve successful bimanual finger coordination, and (2 the distant connectivity among the higher motor areas declines with aging, whereas the local connectivity within the bilateral M1 is enhanced for the complex anti-phase mode. The latter may underlie the elderly’s decreased performance in the complex anti-phase mode of the bimanual finger movement task.
Kiyama, Sachiko; Kunimi, Mitsunobu; Iidaka, Tetsuya; Nakai, Toshiharu
Although bimanual finger coordination is known to decline with aging, it still remains unclear how exactly the neural substrates underlying the coordination differ between young and elderly adults. The present study focused on: (1) characterization of the functional connectivity within the motor association cortex which is required for successful bimanual finger coordination, and (2) to elucidate upon its age-related decline. To address these objectives, we utilized functional magnetic resonance imaging (fMRI) in combination with structural equation modeling (SEM). This allowed us to compare functional connectivity models between young and elderly age groups during a visually guided bimanual finger movement task using both stable in-phase and complex anti-phase modes. Our SEM exploration of functional connectivity revealed significant age-related differences in connections surrounding the PMd in the dominant hemisphere. In the young group who generally displayed accurate behavior, the SEM model for the anti-phase mode exhibited significant connections from the dominant PMd to the non-dominant SPL, and from the dominant PMd to the dominant S1. However, the model for the elderly group's anti-phase mode in which task performance dropped, did not exhibit significant connections within the aforementioned regions. These results suggest that: (1) the dominant PMd acts as an intermediary to invoke intense intra- and inter-hemispheric connectivity with distant regions among the higher motor areas including the dominant S1 and the non-dominant SPL in order to achieve successful bimanual finger coordination, and (2) the distant connectivity among the higher motor areas declines with aging, whereas the local connectivity within the bilateral M1 is enhanced for the complex anti-phase mode. The latter may underlie the elderly's decreased performance in the complex anti-phase mode of the bimanual finger movement task.
Boyles, Jason; Panzer, Stefan; Shea, Charles H
An experiment was conducted to determine whether multi-frequency continuous bimanual circling movements of varying difficulty (1:2, 2:3, 3:4, and 4:5) could be effectively performed following relatively little practice when on-line continuous relative velocity feedback is provided. The between-subjects results indicate extremely effective bimanual multi-frequency performance for all coordination patterns with relatively stable and continuous movements of both limbs. The findings suggest that the previous performance effects using Lissajous feedback with reciprocal movement can be extended to circling movements using on-line relative velocity feedback. Contrary to the long-held position that these coordination patterns result in increasing difficulty, we failed to find systematic relative velocity error, variability, or bias differences between the participants performing the various multi-frequency coordination patterns. Indeed, coordination error, variability, and biases were remarkably low for each of the tasks. The results clearly indicate the ease with which participants are able to produce bimanual coordination patterns typically considered difficult if not impossible when salient visual information is provided that allows the participants to detect and correct their coordination errors.
Full Text Available Modern rehabilitation practices have begun integrating robots, recognizing their significant role in recovery. New and alternative stroke rehabilitation treatments are essential to enhance efficacy and mitigate associated health costs. Today’s robotic interventions can play a significant role in advancing rehabilitation. In addition, robots have an inherent ability to perform tasks accurately and reliably and are typically well suited to measure and quantify performance.Most rehabilitation strategies predominantly target activation of the paretic arm. However, bimanual upper limb rehabilitation research suggests potential in enhancing functional recovery. Moreover studies suggest limb coordination and synchronization can improve treatment efficacy.In this preliminary study, we aimed to investigate and validate our user-driven bimanual system in a reduced intensity rehab practice. A Bimanual Wearable Robotic Device (BWRD with a Master-Slave configuration for the elbow joint was developed to carry out the investigation. The BWRD incorporates position and force sensors for which respective control loops are implemented, and offers varying modes of operation ranging from passive to active training. The proposed system enables the perception of the movements, as well as the forces applied by the hemiparetic arm, with the non-hemiparetic arm. Eight participants with chronic unilateral stroke were recruited to participate in a total of three one-hour sessions per participant, delivered in a week. Participants underwent pre and post training functional assessments along with proprioceptive measures. The post assessment was performed at the end of the last training session.The protocol was designed to engage the user in an assortment of static and dynamic arm matching and opposing tasks. The training incorporates force feedback movements, force feedback positioning, and force matching tasks with same and opposite direction movements. We are able to
Liddy, Joshua J; Zelaznik, Howard N; Huber, Jessica E; Rietdyk, Shirley; Claxton, Laura J; Samuel, Arjmand; Haddad, Jeffrey M
The Microsoft Kinect has been used in studies examining posture and gait. Despite the advantages of portability and low cost, this device has not been used to assess interlimb coordination. Fundamental insights into movement control, variability, health, and functional status can be gained by examining coordination patterns. In this study, we investigated the efficacy of the Microsoft Kinect to capture bimanual coordination relative to a research-grade motion capture system. Twenty-four healthy adults performed coordinated hand movements in two patterns (in-phase and antiphase) at eight movement frequencies (1.00-3.33 Hz). Continuous relative phase (CRP) and discrete relative phase (DRP) were used to quantify the means (mCRP and mDRP) and variability (sdCRP and sdDRP) of coordination patterns. Between-device agreement was assessed using Bland-Altman bias with 95 % limits of agreement, concordance correlation coefficients (absolute agreement), and Pearson correlation coefficients (relative agreement). Modest-to-excellent relative and absolute agreements were found for mCRP in all conditions. However, mDRP showed poor agreement for the in-phase pattern at low frequencies, due to large between-device differences in a subset of participants. By contrast, poor absolute agreement was observed for both sdCRP and sdDRP, while relative agreement ranged from poor to excellent. Overall, the Kinect captures the macroscopic patterns of bimanual coordination better than coordination variability.
Aggarwal, Vikram; Mollazadeh, Mohsen; Davidson, Adam G; Schieber, Marc H; Thakor, Nitish V
The performance of brain-machine interfaces (BMIs) that continuously control upper limb neuroprostheses may benefit from distinguishing periods of posture and movement so as to prevent inappropriate movement of the prosthesis. Few studies, however, have investigated how decoding behavioral states and detecting the transitions between posture and movement could be used autonomously to trigger a kinematic decoder. We recorded simultaneous neuronal ensemble and local field potential (LFP) activity from microelectrode arrays in primary motor cortex (M1) and dorsal (PMd) and ventral (PMv) premotor areas of two male rhesus monkeys performing a center-out reach-and-grasp task, while upper limb kinematics were tracked with a motion capture system with markers on the dorsal aspect of the forearm, hand, and fingers. A state decoder was trained to distinguish four behavioral states (baseline, reaction, movement, hold), while a kinematic decoder was trained to continuously decode hand end point position and 18 joint angles of the wrist and fingers. LFP amplitude most accurately predicted transition into the reaction (62%) and movement (73%) states, while spikes most accurately decoded arm, hand, and finger kinematics during movement. Using an LFP-based state decoder to trigger a spike-based kinematic decoder [r = 0.72, root mean squared error (RMSE) = 0.15] significantly improved decoding of reach-to-grasp movements from baseline to final hold, compared with either a spike-based state decoder combined with a spike-based kinematic decoder (r = 0.70, RMSE = 0.17) or a spike-based kinematic decoder alone (r = 0.67, RMSE = 0.17). Combining LFP-based state decoding with spike-based kinematic decoding may be a valuable step toward the realization of BMI control of a multifingered neuroprosthesis performing dexterous manipulation.
Shea, Charles H; Buchanan, John J; Kennedy, Deanna M
For nearly four decades bimanual coordination, "a prototype of complex motor skills" and apparent "window into the design of the brain," has been intensively studied. Past research has focused on describing and modeling the constraints that allow the production of some coordination patterns while limiting effective performance of other bimanual coordination patterns. More recently researchers have identified a coalition of perception-action constraints that hinder the effective production of bimanual skills. The result has been that given specially designed contexts where one or more of these constraints are minimized, bimanual skills once thought difficult, if not impossible, to effectively produce without very extensive practice can be executed effectively with little or no practice. The challenge is to understand how these contextual constraints interact to allow or inhibit the production of complex bimanual coordination skills. In addition, the factors affecting the stability of bimanual coordination tasks needs to be re-conceptualized in terms of perception-related constraints arising from the environmental context in which performance is conducted and action constraints resident in the neuromotor system.
Morange-Majoux, Francoise; Dellatolas, Georges
Recent theories on the evolution of language (e.g. Corballis, 2009) emphazise the interest of early manifestations of manual laterality and manual specialization in human infants. In the present study, left- and right-hand movements towards a midline object were observed in 24 infants aged 4 months in a constrained condition, in which the hands…
Arrighi, Pieranna; Bonfiglio, Luca; Minichilli, Fabrizio; Cantore, Nicoletta; Carboncini, Maria Chiara; Piccotti, Emily; Rossi, Bruno; Andre, Paolo
Modulation of frontal midline theta (fmθ) is observed during error commission, but little is known about the role of theta oscillations in correcting motor behaviours. We investigate EEG activity of healthy partipants executing a reaching task under variable degrees of prism-induced visuo-motor distortion and visual occlusion of the initial arm trajectory. This task introduces directional errors of different magnitudes. The discrepancy between predicted and actual movement directions (i.e. the error), at the time when visual feedback (hand appearance) became available, elicits a signal that triggers on-line movement correction. Analysis were performed on 25 EEG channels. For each participant, the median value of the angular error of all reaching trials was used to partition the EEG epochs into high- and low-error conditions. We computed event-related spectral perturbations (ERSP) time-locked either to visual feedback or to the onset of movement correction. ERSP time-locked to the onset of visual feedback showed that fmθ increased in the high- but not in the low-error condition with an approximate time lag of 200 ms. Moreover, when single epochs were sorted by the degree of motor error, fmθ started to increase when a certain level of error was exceeded and, then, scaled with error magnitude. When ERSP were time-locked to the onset of movement correction, the fmθ increase anticipated this event with an approximate time lead of 50 ms. During successive trials, an error reduction was observed which was associated with indices of adaptations (i.e., aftereffects) suggesting the need to explore if theta oscillations may facilitate learning. To our knowledge this is the first study where the EEG signal recorded during reaching movements was time-locked to the onset of the error visual feedback. This allowed us to conclude that theta oscillations putatively generated by anterior cingulate cortex activation are implicated in error processing in semi-naturalistic motor
Strauss, Soeren; Woodgate, Philip J W; Sami, Saber A; Heinke, Dietmar
We present an extension of a neurobiologically inspired robotics model, termed CoRLEGO (Choice reaching with a LEGO arm robot). CoRLEGO models experimental evidence from choice reaching tasks (CRT). In a CRT participants are asked to rapidly reach and touch an item presented on the screen. These experiments show that non-target items can divert the reaching movement away from the ideal trajectory to the target item. This is seen as evidence attentional selection of reaching targets can leak into the motor system. Using competitive target selection and topological representations of motor parameters (dynamic neural fields) CoRLEGO is able to mimic this leakage effect. Furthermore if the reaching target is determined by its colour oddity (i.e. a green square among red squares or vice versa), the reaching trajectories become straighter with repetitions of the target colour (colour streaks). This colour priming effect can also be modelled with CoRLEGO. The paper also presents an extension of CoRLEGO. This extension mimics findings that transcranial direct current stimulation (tDCS) over the motor cortex modulates the colour priming effect (Woodgate et al., 2015). The results with the new CoRLEGO suggest that feedback connections from the motor system to the brain's attentional system (parietal cortex) guide visual attention to extract movement-relevant information (i.e. colour) from visual stimuli. This paper adds to growing evidence that there is a close interaction between the motor system and the attention system. This evidence contradicts the traditional conceptualization of the motor system as the endpoint of a serial chain of processing stages. At the end of the paper we discuss CoRLEGO's predictions and also lessons for neurobiologically inspired robotics emerging from this work.
Zelic, Gregory; Mottet, Denis; Lagarde, Julien
The brain has the remarkable ability to bind together inputs from different sensory origin into a coherent percept. Behavioral benefits can result from such ability, e.g., a person typically responds faster and more accurately to cross-modal stimuli than to unimodal stimuli. To date, it is, however, largely unknown whether such multisensory benefits, shown for discrete reactive behaviors, generalize to the continuous coordination of movements. The present study addressed multisensory integration from the perspective of bimanual coordination dynamics, where the perceptual activity no longer triggers a single response but continuously guides the motor action. The task consisted in coordinating anti-symmetrically the continuous flexion-extension of the index fingers, while synchronizing with an external pacer. Three different configurations of metronome were tested, for which we examined whether a cross-modal pacing (audio-tactile beats) improved the stability of the coordination in comparison with unimodal pacing condition (auditory or tactile beats). We found a more stable bimanual coordination for cross-modal pacing, but only when the metronome configuration directly matched the anti-symmetric coordination pattern. We conclude that multisensory integration can benefit the continuous coordination of movements; however, this is constrained by whether the perceptual and motor activities match in space and time.
Marcus H Heitger
Full Text Available In bimanual coordination, older and younger adults activate a common cerebral network but the elderly also have additional activation in a secondary network of brain areas to master task performance. It remains unclear whether the functional connectivity within these primary and secondary motor networks differs between the old and the young and whether task difficulty modulates connectivity. We applied graph-theoretical network analysis (GTNA to task-driven fMRI data in 16 elderly and 16 young participants using a bimanual coordination task including in-phase and anti-phase flexion/extension wrist movements. Network nodes for the GTNA comprised task-relevant brain areas as defined by fMRI activation foci. The elderly matched the motor performance of the young but showed an increased functional connectivity in both networks across a wide range of connectivity metrics, i.e., higher mean connectivity degree, connection strength, network density and efficiency, together with shorter mean communication path length between the network nodes and also a lower betweenness centrality. More difficult movements showed an increased connectivity in both groups. The network connectivity of both groups had "small world" character. The present findings indicate (a that bimanual coordination in the aging brain is associated with a higher functional connectivity even between areas also activated in young adults, independently from task difficulty, and (b that adequate motor coordination in the context of task-driven bimanual control in older adults may not be solely due to additional neural recruitment but also to aging-related changes of functional relationships between brain regions.
Grimm, Florian; Naros, Georgios; Gharabaghi, Alireza
Assistive technology allows for intensive practice and kinematic measurements during rehabilitation exercises. More recent approaches attach a gravity-compensating multi-joint exoskeleton to the upper extremity to facilitate task-oriented training in three-dimensional space with virtual reality feedback. The movement quality, however, is mostly captured through end-point measures that lack information on proximal inter-joint coordination. This limits the differentiation between compensation strategies and genuine restoration both during the exercise and in the course of rehabilitation. We extended in this proof-of-concept study a commercially available seven degree-of-freedom arm exoskeleton by using the real-time sensor data to display a three-dimensional multi-joint visualization of the user's arm. Ten healthy subjects and three severely affected chronic stroke patients performed reach-to-grasp exercises resembling activities of daily living assisted by the attached exoskeleton and received closed-loop online feedback of the three-dimensional movement in virtual reality. Patients in this pilot study differed significantly with regard to motor performance (accuracy, temporal efficiency, range of motion) and movement quality (proximal inter-joint coordination) from the healthy control group. In the course of 20 training and feedback sessions over 4 weeks, these pathological measures improved significantly toward the reference parameters of healthy participants. It was moreover feasible to capture the evolution of movement pattern kinematics of the shoulder and elbow and to quantify the individual degree of natural movement restoration for each patient. The virtual reality visualization and closed-loop feedback of joint-specific movement kinematics makes it possible to detect compensation strategies and may provide a tool to achieve the rehabilitation goals in accordance with the individual capacity for genuine functional restoration; a proposal that warrants
Full Text Available Modulation of frontal midline theta (fmθ is observed during error commission, but little is known about the role of theta oscillations in correcting motor behaviours. We investigate EEG activity of healthy partipants executing a reaching task under variable degrees of prism-induced visuo-motor distortion and visual occlusion of the initial arm trajectory. This task introduces directional errors of different magnitudes. The discrepancy between predicted and actual movement directions (i.e. the error, at the time when visual feedback (hand appearance became available, elicits a signal that triggers on-line movement correction. Analysis were performed on 25 EEG channels. For each participant, the median value of the angular error of all reaching trials was used to partition the EEG epochs into high- and low-error conditions. We computed event-related spectral perturbations (ERSP time-locked either to visual feedback or to the onset of movement correction. ERSP time-locked to the onset of visual feedback showed that fmθ increased in the high- but not in the low-error condition with an approximate time lag of 200 ms. Moreover, when single epochs were sorted by the degree of motor error, fmθ started to increase when a certain level of error was exceeded and, then, scaled with error magnitude. When ERSP were time-locked to the onset of movement correction, the fmθ increase anticipated this event with an approximate time lead of 50 ms. During successive trials, an error reduction was observed which was associated with indices of adaptations (i.e., aftereffects suggesting the need to explore if theta oscillations may facilitate learning. To our knowledge this is the first study where the EEG signal recorded during reaching movements was time-locked to the onset of the error visual feedback. This allowed us to conclude that theta oscillations putatively generated by anterior cingulate cortex activation are implicated in error processing in semi
Boisgontier, Matthieu P.; Serbruyns, Leen; Swinnen, Stephan P.
Practice of a given physical activity is known to improve the motor skills related to this activity. However, whether unrelated skills are also improved is still unclear. To test the impact of physical activity on an unpracticed motor task, 26 young adults completed the international physical activity questionnaire and performed a bimanual coordination task they had never practiced before. Results showed that higher total physical activity predicted higher performance in the bimanual task, controlling for multiple factors such as age, physical inactivity, music practice, and computer games practice. Linear mixed models allowed this effect of physical activity to be generalized to a large population of bimanual coordination conditions. This finding runs counter to the notion that generalized motor abilities do not exist and supports the existence of a “learning to learn” skill that could be improved through physical activity and that impacts performance in tasks that are not necessarily related to the practiced activity. PMID:28265253
Holbrook, Christopher M.; Johnson, Nicholas S.; Steibel, Juan P.; Twohey, Michael B.; Binder, Thomas R.; Krueger, Charles C.; Jones, Michael L.
Improved methods are needed to evaluate barriers and traps for control and assessment of invasive sea lamprey (Petromyzon marinus) in the Great Lakes. A Bayesian state-space model provided reach-specific probabilities of movement, including trap capture and dam passage, for 148 acoustic tagged invasive sea lamprey in the lower Cheboygan River, Michigan, a tributary to Lake Huron. Reach-specific movement probabilities were combined to obtain estimates of spatial distribution and abundance needed to evaluate a barrier and trap complex for sea lamprey control and assessment. Of an estimated 21 828 – 29 300 adult sea lampreys in the river, 0%–2%, or 0–514 untagged lampreys, could have passed upstream of the dam, and 46%–61% were caught in the trap. Although no tagged lampreys passed above the dam (0/148), our sample size was not sufficient to consider the lock and dam a complete barrier to sea lamprey. Results also showed that existing traps are in good locations because 83%–96% of the population was vulnerable to existing traps. However, only 52%–69% of lampreys vulnerable to traps were caught, suggesting that traps can be improved. The approach used in this study was a novel use of Bayesian state-space models that may have broader applications, including evaluation of barriers for other invasive species (e.g., Asian carp (Hypophthalmichthys spp.)) and fish passage structures for other diadromous fishes.
Herrnstadt, Gil; Alavi, Nezam; Randhawa, Bubblepreet Kaur; Boyd, Lara A; Menon, Carlo
Modern rehabilitation practices have begun integrating robots, recognizing their significant role in recovery. New and alternative stroke rehabilitation treatments are essential to enhance efficacy and mitigate associated health costs. Today's robotic interventions can play a significant role in advancing rehabilitation. In addition, robots have an inherent ability to perform tasks accurately and reliably and are typically well suited to measure and quantify performance. Most rehabilitation strategies predominantly target activation of the paretic arm. However, bimanual upper-limb rehabilitation research suggests potential in enhancing functional recovery. Moreover, studies suggest that limb coordination and synchronization can improve treatment efficacy. In this preliminary study, we aimed to investigate and validate our user-driven bimanual system in a reduced intensity rehab practice. A bimanual wearable robotic device (BWRD) with a Master-Slave configuration for the elbow joint was developed to carry out the investigation. The BWRD incorporates position and force sensors for which respective control loops are implemented, and offers varying modes of operation ranging from passive to active training. The proposed system enables the perception of the movements, as well as the forces applied by the hemiparetic arm, with the non-hemiparetic arm. Eight participants with chronic unilateral stroke were recruited to participate in a total of three 1-h sessions per participant, delivered in a week. Participants underwent pre- and post-training functional assessments along with proprioceptive measures. The post-assessment was performed at the end of the last training session. The protocol was designed to engage the user in an assortment of static and dynamic arm matching and opposing tasks. The training incorporates force-feedback movements, force-feedback positioning, and force matching tasks with same and opposite direction movements. We are able to suggest
Ridderikhoff, Arne; Peper, C. E.; Beek, Peter J.
Studies of rhythmic bimanual coordination under dual-task conditions revealed (1) a dependence of secondary task performance on the stability of coordinative tasks, in that secondary task performance was better during in-phase than antiphase coordination, and (2) a shift in the mean relative phasing between the limbs compared to single-task…
Boer, de B.J.; Peper, C.E.; Beek, P.J.
Developmental changes in bimanual coordination were examined in four age groups: 6/7, 10/11, 14/15 years, and young adults. Temporal coupling was assessed through the stabilizing contributions of interlimb interactions related to planning, error correction, and reflexes during rhythmic wrist movemen
Watanabe, Hidenori; Takahashi, Kazutaka; Nishimura, Yukio; Isa, Tadashi
β oscillations in local field potentials, electro-corticography (ECoG), and electroencephalograms (EEG) are ubiquitous in the motor cortex of monkeys and humans. However due to their lack of contributions, compared to other frequency ranges, to decode effector kinematics especially in ECoG signals, spatiotemporal dynamics of ECoG β oscillations has not been examined despite the larger areas that ECoG arrays can cover than standard intracortical multielectrode arrays. Here, we used ECoG grids to cover large areas of motor cortex and some somatosensory cortex in monkeys while they performed an unconstrained reaching and a lever pulling task at two force levels in three dimensional space. We showed that under the pulling task β power increased around movement onset. However, the β phases were locked around the movement onsets and their peak timings were spatially aligned in the motor cortex. These results may indicate that spatiotemporal dynamics of β oscillation conveys task relevant information and that ECoG arrays will be useful to study larger spatiotemporal patterns in the motor cortex, or any cortical areas in general, than intracortical multielectrode arrays.
Full Text Available Controversy exists regarding whether bimanual skill learning can generalize to unimanual performance. For example, some investigators showed that dynamic adaptation could only partially generalize between bilateral and unilateral movement conditions, while others demonstrated complete generalization of visuomotor adaptation. Here, we identified three potential factors that might have contributed to the discrepancy between the two sets of findings. In our first experiment, subjects performed reaching movements toward eight targets bilaterally with a novel force field applied to both arms, then unilaterally with the force field applied to one arm. Results showed that the dynamic adaptation generalized completely from bilateral to unilateral movements. In our second experiment, the same force field was only applied to one arm during both bilateral and unilateral movements. Results indicated complete transfer again. Finally, our subjects performed reaching movements toward a single target with the force field or a novel visuomotor rotation applied only to one arm during both bilateral and unilateral movements. The reduced breadth of experience obtained during bilateral movements resulted in incomplete transfer, which explains previous findings of limited generalization. These findings collectively suggest a substantial overlap between the neural processes underlying bilateral and unilateral movements, supporting the idea that bilateral training, often employed in stroke rehabilitation, is a valid method for improving unilateral performance. However, our findings also suggest that while the neural representations developed during bilateral training can generalize to facilitate unilateral performance, the extent of generalization may depend on the breadth of experience obtained during bilateral training.
Brauchle, Daniel; Vukelić, Mathias; Bauer, Robert; Gharabaghi, Alireza
While robot-assisted arm and hand training after stroke allows for intensive task-oriented practice, it has provided only limited additional benefit over dose-matched physiotherapy up to now. These rehabilitation devices are possibly too supportive during the exercises. Neurophysiological signals might be one way of avoiding slacking and providing robotic support only when the brain is particularly responsive to peripheral input. We tested the feasibility of three-dimensional robotic assistance for reaching movements with a multi-joint exoskeleton during motor imagery (MI)-related desynchronization of sensorimotor oscillations in the β-band. We also registered task-related network changes of cortical functional connectivity by electroencephalography via the imaginary part of the coherence function. Healthy subjects and stroke survivors showed similar patterns-but different aptitudes-of controlling the robotic movement. All participants in this pilot study with nine healthy subjects and two stroke patients achieved their maximum performance during the early stages of the task. Robotic control was significantly higher and less variable when proprioceptive feedback was provided in addition to visual feedback, i.e., when the orthosis was actually attached to the subject's arm during the task. A distributed cortical network of task-related coherent activity in the θ-band showed significant differences between healthy subjects and stroke patients as well as between early and late periods of the task. Brain-robot interfaces (BRIs) may successfully link three-dimensional robotic training to the participants' efforts and allow for task-oriented practice of activities of daily living with a physiologically controlled multi-joint exoskeleton. Changes of cortical physiology during the task might also help to make subject-specific adjustments of task difficulty and guide adjunct interventions to facilitate motor learning for functional restoration, a proposal that warrants
Full Text Available While robot-assisted arm and hand training after stroke allows for intensive task-oriented practice, it has provided only limited additional benefit over dose-matched physiotherapy up to now. These rehabilitation devices are possibly too supportive during the exercises. Neurophysiological signals might be one way of avoiding slacking and providing robotic support only when the brain is particularly responsive to peripheral input.We tested the feasibility of three-dimensional robotic assistance for reach-to-grasp movements with a multi-joint exoskeleton during motor imagery-related desynchronization of sensorimotor oscillations in the β-band only. We also registered task-related network changes of cortical functional connectivity by electroencephalography via the imaginary part of the coherence function.Healthy subjects and stroke survivors showed similar patterns – but different aptitudes – of controlling the robotic movement. All participants in this pilot study with nine healthy subjects and two stroke patients achieved their maximum performance during the early stages of the task. Robotic control was significantly higher and less variable when proprioceptive feedback was provided in addition to visual feedback, i.e. when the orthosis was actually attached to the subject’s arm during the task. A distributed cortical network of task-related coherent activity in the θ-band showed significant differences between healthy subjects and stroke patients as well as between early and late periods of the task.Brain-robot interfaces may successfully link three-dimensional robotic training to the participants’ efforts and allow for task-oriented practice of activities of daily living with a physiologically controlled multi-joint exoskeleton. Changes of cortical physiology during the task might also help to make subject-specific adjustments of task difficulty and guide adjunct interventions to facilitate motor learning for functional restoration.
Hopkins, William D; Phillips, Kimberley A; Bania, Amanda
Whether or not nonhuman primates exhibit population-level handedness remains a topic of considerable scientific debate. Here, we examined handedness for coordinated bimanual actions in a sample of 777 great apes including chimpanzees, bonobos, gorillas, and orangutans. We found population......-level right-handedness in chimpanzees, bonobos and gorillas, but left-handedness in orangutans. Directional biases in handedness were consistent across independent samples of apes within each genus. We suggest that, contrary to previous claims, population-level handedness is evident in great apes but differs...
Tallet, Jessica; Barral, Jérôme; James, Clara; Hauert, Claude-Alain
This study investigated behavioural and electro-cortical reorganizations accompanying intentional switching between two distinct bimanual coordination tapping modes (In-phase and Anti-phase) that differ in stability when produced at the same movement rate. We expected that switching to a less stable tapping mode (In-to-Anti switching) would lead to larger behavioural perturbations and require supplementary neural resources than switching to a more stable tapping mode (Anti-to-In switching). Behavioural results confirmed that the In-to-Anti switching lasted longer than the Anti-to-In switching. A general increase in attention-related neural activity was found at the moment of switching for both conditions. Additionally, two condition-dependent EEG reorganizations were observed. First, a specific increase in cortico-cortical coherence appeared exclusively during the In-to-Anti switching. This result may reflect a strengthening in inter-regional communication in order to engage in the subsequent, less stable, tapping mode. Second, a decrease in motor-related neural activity (increased beta spectral power) was found for the Anti-to-In switching only. The latter effect may reflect the interruption of the previous, less stable, tapping mode. Given that previous results on spontaneous Anti-to-In switching revealing an inverse pattern of EEG reorganization (decreased beta spectral power), present findings give new insight on the stability-dependent neural correlates of intentional motor switching.
Kimmerle, Marliese; Ferre, Claudio L; Kotwica, Kathleen A; Michel, George F
Role-differentiated bimanual manipulation (RDBM) is a complementary movement of both hands that requires differentiation between actions of the hands. Previous research showed that RDBM can be observed in infants as early as 7 months. However, RDBM could be considered a skill only when its frequency, duration, and use is appropriate for the type of manual task, and there is some evidence of intentionality in use. Twenty-four normally developing infants were studied longitudinally at 7, 9, 11, and 13 months to assess the frequency and duration of five clearly different types of RDBM with three "single-part" and three "two-part" toys as they emerge during development. Also, the sequences of actions that lead to RDBM were examined for evidence of "intentionality." The results show that although the each type of RDBM appears early in infancy, RDBM only begins to exhibit the characters of a skill by 13 months. Moreover, the type of toy influences not only the likelihood of eliciting role differentiation, but also the type of RDBM behavior and the organization of the sequence of actions that lead to RDBM. Some useful criteria for defining an infant sensorimotor skill are provided in discussion.
de Poel, HJ; Peper, CE; Beek, PJ
Based on indications that hand dominance is characterized by asymmetrical interlimb coupling strength (with the dominant hand exerting stronger influences on the nondominant hand than vice versa), intentional switches between rhythmic bimanual coordination patterns were predicted to be mediated prim
Dexterous and autonomous manipulation is a key technology for the personal and service robots of the future. Advances in Bimanual Manipulation edited by Bruno Siciliano provides the robotics community with the most noticeable results of the four-year European project DEXMART (DEXterous and autonomous dual-arm hand robotic manipulation with sMART sensory-motor skills: A bridge from natural to artificial cognition). The volume covers a host of highly important topics in the field, concerned with modelling and learning of human manipulation skills, algorithms for task planning, human-robot interaction, and grasping, as well as hardware design of dexterous anthropomorphic hands. The results described in this five-chapter collection are believed to pave the way towards the development of robotic systems endowed with dexterous and human-aware dual-arm/hand manipulation skills for objects, operating with a high degree of autonomy in unstructured real-world environments.
Virginia Way Tong Chu; Terence David Sanger
Practice of movement in virtual-reality and other artificially altered environments has been proposed as a method for rehabilitation following neurological injury and for training new skills in healthy humans. For such training to be useful, there must be transfer of learning from the artificial environment to the performance of desired skills in the natural environment. Therefore an important assumption of such methods is that practice in the altered environment engages the same learning a...
Virginia Way Tong Chu
Full Text Available Practice of movement in virtual-reality and other artificially altered environments has been proposed as a method for rehabilitation following neurological injury and for training new skills in healthy humans. For such training to be useful, there must be transfer of learning from the artificial environment to the performance of desired skills in the natural environment. Therefore an important assumption of such methods is that practice in the altered environment engages the same learning and plasticity mechanisms that are required for skill performance in the natural environment. We test the hypothesis that transfer of learning may fail because the learning and plasticity mechanism that adapts to the altered environment is different from the learning mechanism required for improvement of motor skill. In this paper, we propose that a model that separates skill learning and environmental adaptation is necessary to explain the learning and aftereffects that are observed in virtual reality experiments. In particular, we studied the condition where practice in the altered environment should lead to correct skill performance in the original environment. Our 2-mechanism model predicts that aftereffects will still be observed when returning to the original environment, indicating a lack of skill transfer from the artificial environment to the original environment. To illustrate the model prediction, we tested 10 healthy participants on the interaction between a simple overlearned motor skill (straight hand movements to targets in different directions and an artificially altered visuomotor environment (rotation of visual feedback of the results of movement. As predicted by the models, participants show adaptation to the altered environment and after-effects on return to the baseline environment even when practice in the altered environment should have led to correct skill performance. The presence of aftereffect under all conditions that
Robertson, S D
In 2 experiments, dynamic systems theory predictions concerning intrinsic dynamics and variability of bimanual coordination were examined at different developmental stages. In Experiment 1, ten 4-, 6-, 7-, 8-, and 10-year-old children and adults performed unimanual dominant, unimanual nondominant, and bimanual continuous circle drawing. All tasks were performed at the participants' preferred rate, size, and mode of coordination. The 4-, 6-, and 7-year-old children produced larger circles with longer durations than those of the 8- and 10-year-olds and the adults. That finding demonstrates that younger children display different intrinsic dynamics than older children and adults. The 4-, 6-, and 7-year-old children also displayed more variability in bimanual coordination (more time in less stable patterns of coordination, higher standard deviation in relative phase) and produced more transitions between coordination patterns than the 8- and 10-year-olds and the adults. In Experiment 2, the same participants performed bimanual circles at increasing rates. Consistent with predictions of the HKB model (H. Haken, J. A. S. Kelso, & H. Bunz, 1985), the number of transitions decreased as speed increased. Some support was found for the notion that age-related variables of attention and rate contribute to the increased variability in young children's bimanual coordination.
Full Text Available Khadijah Alattas Department of Ophthalmology, College of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia Objective: To compare patients’ acceptance of and correlate their pain level for bimanual versus metal speculum fixation in intravitreal injections. Design: Prospective analysis. Participants: Seventy-three eyes of 56 patients. Methods: A questionnaire indicating patients’ discomfort and pain grading immediately after intravitreal injections using either bimanual fixation or metal speculum fixation (Barraquer Wire Speculum. Results: Fifty-six patients who underwent intravitreal injections were enrolled in this study for various conditions. Patients’ overall pain and discomfort were as follows, right eye – bimanual was 0.3 on our grading scale with a standard deviation of 0.54, right eye – metal was 1.6 on our grading scale with a standard deviation of 1.5, left eye – bimanual was 0.41 on our grading scale with a standard deviation of 0.87, and left eye – metal was 1.91 on our grading scale with a standard deviation of 1.14 (P=0.003. Conclusion: Patients who underwent bimanual fixation had a much more comfortable experience with less pain in comparison to patients who underwent metal speculum fixation. Keywords: AMD, diabetic retionpathy, Avastin, eye injection
Full Text Available In the present study, we tested right- and left-handed participants in a Poffenberger paradigm with bimanual responses and hands either in an anatomical or in a left-right inverted posture. We observed a significant positive crossed-uncrossed difference (CUD in reaction times for both manual dominance groups and both response postures. These results rule out an explanation of the CUD in terms of stimulus-response spatial compatibility and provide convincing evidence on the important role of interhemispheric callosal transfer in bimanual responding in right- as well as left-handed individuals.
Jover, Marianne; Schmitz, Christina; Centelles, Laurie; Chabrol, Brigitte; Assaiante, Christine
Aim: Postural control is a fundamental component of action in which deficits have been shown to contribute to motor difficulties in children with developmental coordination disorder (DCD). The purpose of this study was to examine anticipatory postural adjustments (APAs) in children with DCD in a bimanual load-lifting task. Method: Sixteen children…
Mulvey, G. M.; Ringenbach, S. D. R.; Jung, M. L.
Background: Research on unimanual tasks suggested that motor asymmetries between hands may be reduced in people with Down syndrome. Our study examined handedness (as assessed by hand performance) and perceptual-motor integration effects on bimanual coordination. Methods: Adults with Down syndrome (13 non-right-handed, 22 right-handed), along with…
Hung, Ya-Ching; Casertano, Lorenzo; Hillman, Andrew; Gordon, Andrew M.
Recent studies have suggested efficacy of intensive bimanual training in improving the quality and quantity of affected hand use in children with hemiplegia. However, it is not known whether such training affects the coordination of the two hands. In the present study, 20 children with congenital hemiplegia (age 4-10 years; MACS levels I-II) were…
Murian, Alexandre; Deschamps, Thibault; Bourbousson, Jérôme; Temprado, Jean Jacques
The present study investigated the influence of a bilateral exhaustive exercise on the stability of bimanual anti-phase coordination pattern and attentional demands. Eight subjects performed the anti-phase coordination pattern in two sessions: an Exhausting Session and a Control Session. During the Exhausting Session, subjects performed the bimanual coordination after exhaustion of forearms muscles (i.e. endurance time test). For the Control Session, no endurance time test was previously designed before the performance of anti-phase coordination. Within these experimental sessions, two levels of load (loaded and unload) and two frequencies (1.75 and 2.25 Hz) were also manipulated during the bimanual task. Attentional demands associated with performing the anti-phase coordination pattern was measured via a probe reaction time task (RT). The results showed that relative phase variability was higher for the fastest frequency after the exhaustive exercise. Moreover, as a result of the previous muscle exercise, the observed phase coupling was less accurate. No significant effect was found concerning the attentional demands as assessed through RT. The present findings suggest that the muscle exhaustion affects bimanual performance at a more peripheral level.
Hilger, Allison I.; Zelaznik, Howard; Smith, Anne
Purpose: Stuttering involves a breakdown in the speech motor system. We address whether stuttering in its early stage is specific to the speech motor system or whether its impact is observable across motor systems. Method: As an extension of Olander, Smith, and Zelaznik (2010), we measured bimanual motor timing performance in 115 children: 70…
Isenhower, Robert W.; Marsh, Kerry L.; Richardson, Michael J.; Helt, Molly; Schmidt, R. C.; Fein, Deborah
Impairments in motor coordination are a common behavioral manifestation of autism spectrum disorder (ASD). We, therefore, used a drumming methodology to examine rhythmic bimanual coordination in children diagnosed with ASD (M = 47.3 months) and age-matched typically developing (TD) children (M = 42.6 months). Both groups were instructed to drum on…
Although bimanual finger coordination is known to decline with aging, it still remains unclear how exactly the neural substrates underlying the coordination differ between young and elderly adults. The present study focused on: (1) characterization of the functional connectivity within the motor association cortex which is required for successful bimanual finger coordination, and (2) to elucidate upon its age-related decline. To address these objectives, we utilized functional magnetic resona...
Peper, C Lieke E; de Boer, Betteco J; de Poel, Harjo J; Beek, Peter J
The relation between movement amplitude and the strength of interlimb interactions was examined by comparing bimanual performance at different amplitude ratios (1:2, 1:1, and 2:1). For conditions with unequal amplitudes, the arm moving at the smaller amplitude was predicted to be more strongly affected by the contralateral arm than vice versa. This prediction was based on neurophysiological considerations and the HKB model of coupled oscillators. Participants performed rhythmic bimanual forearm movements at prescribed amplitude relations. After a brief mechanical perturbation of one arm, the relaxation process back to the initial coordination pattern was examined. This analysis focused on phase adaptations in the unperturbed arm, as these reflect the degree to which the movements of this arm were affected by the coupling influences stemming from the contralateral (perturbed) arm. The thus obtained index of coupling (IC) reflected the relative contribution of the unperturbed arm to the relaxation process. As predicted IC was larger when the perturbed arm moved at a larger amplitude than did the unperturbed arm, indicating that coupling strength scaled with movement amplitude. This result was discussed in relation to previous research regarding sources of asymmetry in coupling strength and the effects of amplitude disparity on interlimb coordination.
Aarts, P.B.M.; Jongerius, P.H.; Geerdink, Y.A.; Limbeek, J. van; Geurts, A.C.H.
BACKGROUND: In children with unilateral spastic cerebral palsy (CP), there is only limited evidence for the effectiveness of modified constraint-induced movement therapy (mCIMT). OBJECTIVE: To investigate whether 6 weeks of mCIMT followed by 2 weeks of bimanual task-specific training (mCIMT-BiT) in
Full Text Available Cataract surgery has evolved over the past few decades with progressive decrease in the size of the incision. Originally from 12 mm intracapsular incision to bimanual phacoemulsification (Micro - Phaco that has incision size of just 700 microns. In the pres ent comparative PROSPECTIVE study best corrected visual acuity postoperatively and surgically induced astigmatism were compared in routine Phacoemulsification technique and bimanual phaco (Micro - Phaco 60 eyes were studied. There was no statistically signi ficant difference in postoperative best corrected visual acuity (BCVA of patients operated with Micro - Phaco or routine Phacoemulsification. There was difference in surgically induced astigmatism (SIA ; average SIA in microphaco was 0.5972 as against 0.832 8 in routine Phacoemulsification.
Squeri, Valentina; Sciutti, Alessandra; Gori, Monica; Masia, Lorenzo; Sandini, Giulio; Konczak, Juergen
Humans routinely use both of their hands to gather information about shape and texture of objects. Yet, the mechanisms of how the brain combines haptic information from the two hands to achieve a unified percept are unclear. This study systematically measured the haptic precision of humans exploring a virtual curved object contour with one or both hands to understand if the brain integrates haptic information from the two hemispheres. Bayesian perception theory predicts that redundant information from both hands should improve haptic estimates. Thus exploring an object with two hands should yield haptic precision that is superior to unimanual exploration. A bimanual robotic manipulandum passively moved the hands of 20 blindfolded, right-handed adult participants along virtual curved contours. Subjects indicated which contour was more "curved" (forced choice) between two stimuli of different curvature. Contours were explored uni- or bimanually at two orientations (toward or away from the body midline). Respective psychophysical discrimination thresholds were computed. First, subjects showed a tendency for one hand to be more sensitive than the other with most of the subjects exhibiting a left-hand bias. Second, bimanual thresholds were mostly within the range of the corresponding unimanual thresholds and were not predicted by a maximum-likelihood estimation (MLE) model. Third, bimanual curvature perception tended to be biased toward the motorically dominant hand, not toward the haptically more sensitive left hand. Two-handed exploration did not necessarily improve haptic sensitivity. We found no evidence that haptic information from both hands is integrated using a MLE mechanism. Rather, results are indicative of a process of "sensory selection", where information from the dominant right hand is used, although the left, nondominant hand may yield more precise haptic estimates.
Charles, Steve; Williams, Roy
Data describing the microsurgeon's hand dynamics was recorded and analyzed in order to provide an accurate model for the telemicrosurgery application of the Bimanual Telemicro-operation Test Bed. The model, in turn, will guide the development of algorithms for the control of robotic systems in bimanual telemicro-operation tasks. Measurements were made at the hand-tool interface and include position, acceleration and force between the tool-finger interface. Position information was captured using an orthogonal pulsed magnetic field positioning system resulting in measurements in all six degrees-of-freedom (DOF). Acceleration data at the hands was obtained using accelerometers positioned in a triaxial arrangement on the back of the hand allowing measurements in all three cartesian-coordinate axes. Force data was obtained by using miniature load cells positioned between the tool and the finger and included those forces experienced perpendicular to the tool shaft and those transferred from the tool-tissue site. Position data will provide a minimum/maximum reference frame for the robotic system's work space or envelope. Acceleration data will define the response times needed by the robotic system in order to emulate and subsequently outperform the human operator's tool movements. The force measurements will aid in designing a force-reflective, force-scaling system as well as defining the range of forces the robotic system will encounter. All analog data was acquired by a 16-channel analog-to-digital conversion system residing in a IBM PC/AT-compatible computer at the Center's laboratory. The same system was also used to analyze and present the data.
Geerdink, Y.A.; Aarts, P.; Geurts, A.C.H.
The goal of this study was to determine the progression of manual dexterity during 6 weeks (54h) (modified) constraint-induced movement therapy ((m)CIMT) followed by 2 weeks (18h) bimanual training (BiT) in children with unilateral spastic cerebral palsy (CP), to establish whether and when a maximal
Reichenbach, Alexandra; Bresciani, Jean-Pierre; Bulthoff, Heinrich H.;
voluntary control of movements by complementing the other senses to accomplish the movement goal. Investigations into the neural correlates of vestibular contribution to voluntary action in humans are challenging and have progressed far less than research on corresponding visual and proprioceptive...... involvement. Here, we demonstrate for the first time with event-related TMS that the posterior part of the right medial intraparietal sulcus processes vestibular signals during a goal-directed reaching task with the dominant right hand. This finding suggests a qualitative difference between the processing...... of vestibular vs. visual and proprioceptive signals for controlling voluntary movements, which are pre-dominantly processed in the left posterior parietal cortex. Furthermore, this study reveals a neural pathway for vestibular input that might be distinct from the processing for reflexive or cognitive functions...
Suellen A. Bottesini
Full Text Available O estudo teve por objetivo analisar a preferência manual de crianças ao alcançar objetos de diferentes tamanhos nas idades de 4, 6, 8 e 36 meses. Para tanto, nove crianças saudáveis foram posicionadas em uma cadeira reclinada para trás a 50º com a horizontal e a elas foram apresentados quatro objetos de rigidez e tamanhos distintos. Foram coletados longitudinalmente 524 alcances aos 4, 6, 8 e 36 meses, sendo analisadas as variáveis mão preferida no alcance e índice de contribuição para os alcances bimanuais. Constatou-se que a mão preferida no alcance no decorrer dos meses foi a direita e que somente aos 6 meses o tamanho dos objetos influenciou a preferência manual: as crianças fizeram preferencialmente alcances com a mão direita para objetos pequenos, e mão esquerda para os grandes. Nos alcances bimanuais, constatou-se que, em geral, a mão que primeiro toca o objeto é a mão mais ativa durante todo o movimento de alcançar. Provavelmente porque a rigidez seja menos visualmente percebida do que o tamanho, só este influencia o alcance aos 6 meses, idade em que o lactente refina o movimento de alcance. O tamanho o influencia aos 6 meses, idade em que o movimento de alcançar se encontra em fase de refinamento: objetos pequenos que exigem maior precisão foram alcançados com a mão direita (mão preferida; e objetos grandes, que não exigem precisão para serem apreendidos, foram alcançados com a mão esquerda.The purpose of this study was to analyse infants' and toddlers' manual preference in reaching objects of different sizes and rigidity at the ages of 4, 6, 8, and 36 months. Four objects of different size and stiffness were presented to nine healthy infants leaning on a chair at 50º. A total of 524 reaching movements were analysed longitudinally to verify manual preference and the index of contribution of each hand for bimanual reaching. Results showed preference of the right hand for reaching objects; only at the age
Lafe, Charley W; Pacheco, Matheus M; Newell, Karl M
The effect of the intermittency of visual information in the bimanual coordination of an isometric force coordination task was investigated as a function of criterion force level. Eight levels of visual information intermittency (.2-25.6 Hz) were used in blocked fashion at each force level. Participants were required to produce a constant force output matching as accurately as possible the criterion force target. The results showed that performance improved as the intermittency of visual information was reduced-this effect being a function of force level. The distribution of the relative phase through the trial revealed a preference for the two hands to be coupled together (in-phase) at the slower rates of visual presentation (~.2 Hz). However, as the rate of visual feedback was increased (up to ~25.6 Hz), there was a transition to predominantly a negative correlation pattern (anti-phase). The pattern of bimanual coordination in this isometric tracking task is driven by the availability of information for error correction and the interactive influence of perceptual-motor constraints.
Stacey L Gorniak
Full Text Available OBJECTIVE: Studies of bimanual actions similar to activities of daily living (ADLs are currently lacking in evaluating fine motor control in Parkinson's disease patients implanted with bilateral subthalamic deep brain stimulators. We investigated basic time and force characteristics of a bimanual task that resembles performance of ADLs in a group of bilateral subthalamic deep brain stimulation (DBS patients. METHODS: Patients were evaluated in three different DBS parameter conditions off stimulation, on clinically derived stimulation parameters, and on settings derived from a patient-specific computational model. Model-based parameters were computed as a means to minimize spread of current to non-motor regions of the subthalamic nucleus via Cicerone Deep Brain Stimulation software. Patients were evaluated off parkinsonian medications in each stimulation condition. RESULTS: The data indicate that DBS parameter state does not affect most aspects of fine motor control in ADL-like tasks; however, features such as increased grip force and grip symmetry varied with the stimulation state. In the absence of DBS parameters, patients exhibited significant grip force asymmetry. Overall UPDRS-III and UPDRS-III scores associated with hand function were lower while patients were experiencing clinically-derived or model-based parameters, as compared to the off-stimulation condition. CONCLUSION: While bilateral subthalamic DBS has been shown to alleviate gross motor dysfunction, our results indicate that DBS may not provide the same magnitude of benefit to fine motor coordination.
Muetzel, Ryan L; Collins, Paul F; Mueller, Bryon A; M Schissel, Ann; Lim, Kelvin O; Luciana, Monica
Cross-sectional and longitudinal volumetric studies suggest that the corpus callosum (CC) continues to mature structurally from infancy to adulthood. Diffusion tensor imaging (DTI) provides in vivo information about the directional organization of white matter microstructure and shows potential for elucidating even more subtle brain changes during adolescent development. We used DTI to examine CC microstructure in healthy right-handed adolescents (n=92, ages 9-24 years) and correlated the imaging data with motor task performance. The primary DTI variable was fractional anisotropy (FA), which reflects the degree of white matter's directional organization. Participants completed an alternating finger tapping test to assess interhemispheric transfer and motor speed. Task performance was significantly correlated with age. Analyses of variance indicated that 9- to 11-year-olds generally performed worse than each of the older groups. Males outperformed females. Significant positive correlations between age and FA were observed in the splenium of the CC, which interconnects posterior cortical regions. Analyses of variance indicated that individuals older than 18 years had significantly higher FA than 9- to 11-year-olds. FA levels in the genu and splenium correlated significantly with task performance. Regression analyses indicated that bimanual coordination was significantly predicted by age, gender, and splenium FA. Decreases in alternating finger tapping time and increases in FA likely reflect increased myelination in the CC and more efficient neuronal signal transmission. These findings expand upon existing neuroimaging reports of CC development by showing associations between bimanual coordination and white matter microstructural organization in an adolescent sample.
Volman, M.J.M.; Geuze, R.H.
A dynamic pattern approach is used to examine the relative phase stability of rhythmic coordination in 24 children with a Developmental Coordination Disorder (DCD) and 24 matched controls in two functionally different tasks - a within-subject task (bimanual coordination) and a subject-environment ta
Gordon, Andrew M
Cerebral palsy is caused by early damage to the developing brain, as the most common pediatric neurological disorder. Hemiplegia (unilateral spastic cerebral palsy) is the most common subtype, and the resulting impairments, lateralized to one body side, especially affect the upper extremity, limiting daily function. This chapter first describes the pathophysiology and mechanisms underlying impaired upper extremity control of cerebral palsy. It will be shown that the severity of impaired hand function closely relates to the integrity of the corticospinal tract innervating the affected hand. It will also shown that the developing corticospinal tract can reorganize its connectivity depending on the timing and location of CNS injury, which also has implications for the severity of hand impairments and rehabilitation. The mechanisms underlying impaired motor function will be highlighted, including deficits in movement execution and planning and sensorimotor integration. It will be shown that despite having unimanual hand impairments, bimanual movement control deficits and mirror movements also impact function. Evidence for motor learning-based therapies including Constraint-Induced Movement Therapy and Bimanual Training, and the possible pathophysiological predictors of treatment outcome and plasticity will be described. Finally, future directions for rehabilitations will be presented.
Iandolo, Riccardo; Squeri, Valentina; De Santis, Dalia; Giannoni, Psiche; Morasso, Pietro; Casadio, Maura
Is there any difference between matching the position of the hands by asking the subjects to move them to the same spatial location or to mirror-symmetric locations with respect to the body midline? If the motion of the hands were planned in the extrinsic space, the mirror-symmetric task would imply an additional challenge, because we would need to flip the coordinates of the target on the other side of the workspace. Conversely, if the planning were done in intrinsic coordinates, in order to move both hands to the same spot in the workspace, we should compute different joint angles for each arm. Even if both representations were available to the subjects, the two tasks might lead to different results, providing some cue on the organization of the "body schema". In order to answer such questions, the middle fingertip of the non-dominant hand of a population of healthy subjects was passively moved by a manipulandum to 20 different target locations. Subjects matched these positions with the middle fingertip of their dominant hand. For most subjects, the matching accuracy was higher in the extrinsic modality both in terms of systematic error and variability, even for the target locations in which the configuration of the arms was the same for both modalities. This suggests that the matching performance of the subjects could be determined not only by proprioceptive information but also by the cognitive representation of the task: expressing the goal as reaching for the physical location of the hand in space is apparently more effective than requiring to match the proprioceptive representation of joint angles.
Quezada-Ruiz, Carlos; Cano-Hidalgo, Rene Alfredo
Antecedentes: el desgarro retiniano gigante es la rotura del espesor total de la retina neurosensorial con extensión circunferencial de 3 o más husos horarios aunado a desprendimiento de vítreo posterior, y constituye uno de los escenarios quirúrgicos más complejos para el cirujano de retina y vítreo. No existe consenso en cuanto a su manejo; sin embargo, tradicionalmente se ha empleado un abordaje que combina lensectomía, cerclaje y vitrectomía. Objetivo: reportar la evolución a dos años de 5 pacientes con desgarro gigante tratados con vitrectomía 23 g, abordaje bimanual, sin lensectomía y sin cerclaje escleral. Material y métodos: estudio descriptivo, retrospectivo de pacientes con desgarro retiniano gigante, tratados con vitrectomía 23 g, abordaje bimanual, sin lensectomía ni cerclaje escleral. Se estudiaron la edad, estado del cristalino, etiología y extensión del desgarro, agudeza visual, resultado anatómico, taponamiento usado, criopexia o láser. Resultados: se incluyeron 3 pacientes con miopía alta, 1 con traumatismo contuso y 1 con síndrome de Wagner-Stickler. La extensión del desgarro fue de 120 a 280°. Todos con éxito anatómico y mejoría de la agudeza visual. Un paciente con vitreorretinopatía proliferativa se reintervino y la retina permaneció aplicada hasta el final del periodo analizado. Conclusiones: en este selecto grupo de pacientes la vitrectomía calibre 23 con abordaje bimanual, sin cerclaje escleral y sin tocar el cristalino, dio buenos resultados anatómicos y visuales en un seguimiento a dos años. Para establecer el papel que corresponde a esta técnica en el tratamiento de esta compleja patología se requieren estudios prospectivos y comparativos.
Bogaerts, H; Buekers, MJ; Zaal, FT; Swinnen, SP
Two experiments are reported in which bimanual coordination tasks were performed under correct and transformed visual feedback conditions. Participants were to generate cyclical line-drawing patterns, with varying degrees of coordinative stability, while perceiving correct or transformed visual info
van Ruitenbeek, Peter; Serbruyns, Leen; Solesio-Jofre, Elena; Meesen, Raf; Cuypers, Koen; Swinnen, Stephan P
Declines in both cortical grey matter and bimanual coordination performance are evident in healthy ageing. However, the relationship between ageing, bimanual performance, and grey matter loss remains unclear, particularly across the whole adult lifespan. Therefore, participants (N = 93, range 20-80 years) performed a complex Bimanual Tracking Task, and structural brain images were obtained using magnetic resonance imaging. Analyses revealed that age correlated negatively with task performance. Voxel-based morphometry analysis revealed that age was associated with grey matter declines in task-relevant cortical areas and that grey matter in these areas was negatively associated with task performance. However, no evidence for a mediating effect of grey matter in age-related bimanual performance decline was observed. We propose a new hypothesis that functional compensation may account for the observed absence of mediation, which is in line with the observed pattern of increased inter-individual variance in performance with age.
Full Text Available Akira Watanabe, Tamaki Gekka, Hiroshi Tsuneoka Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan Background: As a method of treatment for a dropped lens nucleus, which occurred during cataract surgery, the dropped lens nucleus was removed through the corneal wound without using pars plana vitrectomy (PPV. After vitrectomy, the dropped lens nucleus was floated on the perfluorocarbon liquid (PFCL. The floating lens nucleus was then phacoemulsified and aspirated. During surgery, irrigation from the anterior chamber was performed. This method was very effective for treatment of a dropped hard nucleus.Case report: During cataract surgery on the left eye of an 80-year-old woman, a posterior capsule rupture occurred. As a result, the lens nucleus dropped into the vitreous cavity. Irrigation to the anterior chamber was performed, with an anterior chamber maintainer inserted through a newly created side port at the corneal limbus. A vitreous cutter and a light guide were inserted in order to perform vitrectomy through the corneal incisions that were created for the cataract surgery. After vitrectomy, the dropped lens nucleus was floated using PFCL. The floating lens nucleus was removed by a bimanual phacoemulsification technique, with the anterior chamber irrigation continuing. The separation of the irrigation port and the aspiration port allowed for effective treatment of the dropped nucleus that was floating on the PFCL, even using a phacoemulsification machine with a peristaltic pump system. Safe and effective vitrectomy, similar to a PPV, could be performed with this method using three corneal ports.Conclusion: This technique may allow safer and more effective treatment for a dropped lens nucleus compared with conventional PPV. With this technique, corneal distortion due to surgical manipulation can lead to reduced visibility of the posterior eye. Keywords: dislocated lens, transcorneal vitrectomy, bimanual
U.S. Environmental Protection Agency — The Reach Address Database (RAD) stores the reach address of each Water Program feature that has been linked to the underlying surface water features (streams,...
Gooijers, Jolien; Beets, Iseult A M; Albouy, Genevieve; Beeckmans, Kurt; Michiels, Karla; Sunaert, Stefan; Swinnen, Stephan P
Years following the insult, patients with traumatic brain injury often experience persistent motor control problems, including bimanual coordination deficits. Previous studies revealed that such deficits are related to brain structural white and grey matter abnormalities. Here, we assessed, for the first time, cerebral functional activation patterns during bimanual movement preparation and performance in patients with traumatic brain injury, using functional magnetic resonance imaging. Eighteen patients with moderate-to-severe traumatic brain injury (10 females; aged 26.3 years, standard deviation = 5.2; age range: 18.4-34.6 years) and 26 healthy young adults (15 females; aged 23.6 years, standard deviation = 3.8; age range: 19.5-33 years) performed a complex bimanual tracking task, divided into a preparation (2 s) and execution (9 s) phase, and executed either in the presence or absence of augmented visual feedback. Performance on the bimanual tracking task, expressed as the average target error, was impaired for patients as compared to controls (P traumatic brain injury patients showed enhanced activations compared with controls in frontal (left dorsolateral prefrontal cortex, left lateral anterior prefrontal cortex, and left orbitofrontal cortex), parietal (bilateral inferior parietal lobe, bilateral superior parietal lobe, right precuneus, right primary somatosensory cortex), occipital (right striate and extrastriate visual cortices), and subcortical (left cerebellum crus II) areas (P's traumatic brain injury (i.e. decreased neural differentiation). In sum, our findings point towards poorer predictive control in traumatic brain injury patients in comparison to controls. Moreover, irrespective of the feedback condition, overactivations were observed in traumatically brain injured patients during movement execution, pointing to more controlled processing of motor task performance.
... t want them to. If you have a movement disorder, you experience these kinds of impaired movement. Dyskinesia ... movement and is a common symptom of many movement disorders. Tremors are a type of dyskinesia. Nerve diseases ...
Popular culture reflects both the interests of and the issues affecting the general public. As concerns regarding climate change and its impacts grow, is it permeating into popular culture and reaching that global audience?
REACH guidelines may require teratology testing for new and existing chemicals. This chapter discusses procedures to assess the need for teratology testing and the conduct and interpretation of teratology tests where required.
Full Text Available CONTEXTUALIZAÇÃO: Estudos têm identificado que as propriedades dos objetos induzem os ajustes no alcance; no entanto, poucos investigaram a influência específica do tamanho e rigidez dos objetos em lactentes jovens. OBJETIVO: Verificar se lactentes de 4 a 6 meses realizam ajustes proximais e distais ao alcançarem objetos de diferentes tamanhos e rigidez. MÉTODOS: Nove lactentes saudáveis foram posicionados em uma cadeira inclinada a 50º. Quatro objetos foram apresentados, um rígido grande (RG, um rígido pequeno (RP, um maleável grande (MG e um maleável pequeno (MP, por um período de 1 minuto cada. Em um total de 384 alcances, foram analisados os ajustes proximais (alcance uni e bimanual e distais (orientação da mão horizontal, vertical e oblíqua; mão aberta, fechada e semi-aberta e o sucesso do alcance dos objetos. RESULTADOS: Constatou-se ajuste bimanual para o objeto RG e unimanual para os demais. A orientação da mão oblíqua foi predominante no toque dos objetos, enquanto para a preensão dos mesmos, a predominância foi a vertical, principalmente para o objeto RG. A orientação horizontal não foi observada na preensão do objeto RG. A mão semi-aberta foi mais freqüente no início do alcance para todos os objetos, enquanto no toque do objeto RG a mão aberta foi predominante. O sucesso do alcance foi maior para os objetos maleáveis (MG, MP do que para os rígidos (RG e RP. CONCLUSÃO: Lactentes jovens estudados são capazes de planejar e ajustar seus movimentos baseados na percepção das propriedades físicas dos objetos, o que sugere interação percepção-ação.BACKGROUND: Studies have identified that object properties lead to adjustments to reaching. However, few have investigated the specific influence of object size and rigidity among young infants. OBJECTIVE: To verify whether four to six-month-old infants make proximal and distal adjustments when reaching for objects of different sizes and rigidity. METHOD
Yu, Ningbo; Xu, Chang; Li, Huanshuai; Wang, Kui; Wang, Liancheng; Liu, Jingtai
Disabilities after neural injury, such as stroke, bring tremendous burden to patients, families and society. Besides the conventional constrained-induced training with a paretic arm, bilateral rehabilitation training involves both the ipsilateral and contralateral sides of the neural injury, fitting well with the fact that both arms are needed in common activities of daily living (ADLs), and can promote good functional recovery. In this work, the fusion of a gesture sensor and a haptic sensor with force feedback capabilities has enabled a bilateral rehabilitation training therapy. The Leap Motion gesture sensor detects the motion of the healthy hand, and the omega.7 device can detect and assist the paretic hand, according to the designed cooperative task paradigm, as much as needed, with active force feedback to accomplish the manipulation task. A virtual scenario has been built up, and the motion and force data facilitate instantaneous visual and audio feedback, as well as further analysis of the functional capabilities of the patient. This task-oriented bimanual training paradigm recruits the sensory, motor and cognitive aspects of the patient into one loop, encourages the active involvement of the patients into rehabilitation training, strengthens the cooperation of both the healthy and impaired hands, challenges the dexterous manipulation capability of the paretic hand, suits easy of use at home or centralized institutions and, thus, promises effective potentials for rehabilitation training. PMID:26999149
de Boer, Betteco J; Peper, C Lieke E; Beek, Peter J
Because bimanual coordinative stability is governed by interlimb coupling, we examined how learning a new pattern (90°) was reflected in changes in the underlying interlimb interactions. Three interlimb interaction sources were distinguished: integrated timing of feedforward control signals, error corrections based on perceived relative phase, and phase entrainment by contralateral afference. By comparing 4 tasks that involve these interactions to a different extent, changes in the stabilizing contributions of these coupling sources could be studied. Furthermore, we studied how the learning process and changes in the underlying interactions were influenced by attentional focus (internal vs. external), and we examined retention of the learned pattern and transfer to the mirror-symmetrical pattern (270°). Results showed that stability and accuracy of the new pattern increased significantly with learning, due to improved integrated timing and error correction. Integrated timing improved first, possibly providing a reference frame for the error corrections that subsequently became more effective. Despite some qualitative differences in the learning process, neither performance of the learned pattern nor the underlying interlimb interactions was influenced by attentional focus. Whereas the learned pattern improved directly after practice, transfer followed later, suggesting that a more general representation was formed at a slower rate after practice.
Wu, Swei-Pi; Loiu, Yi; Chien, Te Hong
This study utilizes a psychophysical approach to examine the effects on carrying capacity for bi-manual carrying tasks involving different handle positions and carrying ranges. A total of 16 female subjects participated in the experiment in groups of two people, and each group of subjects performed the tasks in a random order with 12 different combinations of carrying task. The independent variables are handle position (upper, middle, lower) and carrying range (F-F: floor height carried to floor height, F-W: floor height carried to waist height, W-W: waist height carried to waist height, W-F: waist height carried to floor height), the dependent variable is the maximum acceptable carried weight (MAWC), heart rate (HR), and the rating of perceived exertion (RPE). The results show that the handle position has a significant effect on MAWC and overall RPE but no significant effect on HR. Carrying range has a significant effect on the MAWC and HR, but no significant effect on overall HR. The handle position and carrying range have a significant interaction on the MAWC and HR. The RPE for different body parts shows significant differences, and the hands feel the most tired. Overall, this study confirms that the lower handle position with the W-W carrying range is the best combination for a two-person carrying task.
Full Text Available Disabilities after neural injury, such as stroke, bring tremendous burden to patients, families and society. Besides the conventional constrained-induced training with a paretic arm, bilateral rehabilitation training involves both the ipsilateral and contralateral sides of the neural injury, fitting well with the fact that both arms are needed in common activities of daily living (ADLs, and can promote good functional recovery. In this work, the fusion of a gesture sensor and a haptic sensor with force feedback capabilities has enabled a bilateral rehabilitation training therapy. The Leap Motion gesture sensor detects the motion of the healthy hand, and the omega.7 device can detect and assist the paretic hand, according to the designed cooperative task paradigm, as much as needed, with active force feedback to accomplish the manipulation task. A virtual scenario has been built up, and the motion and force data facilitate instantaneous visual and audio feedback, as well as further analysis of the functional capabilities of the patient. This task-oriented bimanual training paradigm recruits the sensory, motor and cognitive aspects of the patient into one loop, encourages the active involvement of the patients into rehabilitation training, strengthens the cooperation of both the healthy and impaired hands, challenges the dexterous manipulation capability of the paretic hand, suits easy of use at home or centralized institutions and, thus, promises effective potentials for rehabilitation training.
Yu, Ningbo; Xu, Chang; Li, Huanshuai; Wang, Kui; Wang, Liancheng; Liu, Jingtai
Disabilities after neural injury, such as stroke, bring tremendous burden to patients, families and society. Besides the conventional constrained-induced training with a paretic arm, bilateral rehabilitation training involves both the ipsilateral and contralateral sides of the neural injury, fitting well with the fact that both arms are needed in common activities of daily living (ADLs), and can promote good functional recovery. In this work, the fusion of a gesture sensor and a haptic sensor with force feedback capabilities has enabled a bilateral rehabilitation training therapy. The Leap Motion gesture sensor detects the motion of the healthy hand, and the omega.7 device can detect and assist the paretic hand, according to the designed cooperative task paradigm, as much as needed, with active force feedback to accomplish the manipulation task. A virtual scenario has been built up, and the motion and force data facilitate instantaneous visual and audio feedback, as well as further analysis of the functional capabilities of the patient. This task-oriented bimanual training paradigm recruits the sensory, motor and cognitive aspects of the patient into one loop, encourages the active involvement of the patients into rehabilitation training, strengthens the cooperation of both the healthy and impaired hands, challenges the dexterous manipulation capability of the paretic hand, suits easy of use at home or centralized institutions and, thus, promises effective potentials for rehabilitation training.
Hu, Xiaogang; Newell, Karl M
This study examined the question of whether and how the influence of visual information on force coordination patterns is dependent on the settings of a task asymmetry constraint. In a bimanual isometric force experiment, the task asymmetry was manipulated via imposing different coefficients on the index finger forces such that the weighted sum of the finger forces matched the target force. The environmental constraint was quantified by the visual performance error and was manipulated through the change of visual gain (number of pixels on the screen representing the unit of force). The constraint arising from the individual was quantified by the bilateral coupling effect (i.e., symmetric force production) between hands. The results revealed improved performance in terms of lower variability and performance error and more complex total force structure with higher visual gain. The influence of visual gain on the force coordination pattern, however, was found to be dependent on the task coefficients imposed on the finger forces. Namely, the force sharing between hands became more symmetric with high visual gain only when the right finger force had the higher coefficient, and an error-compensatory strategy was evident with high gain only when symmetric coefficients were imposed on the two fingers. The findings support the proposition that the motor coordination and control patterns are organized by the interactive influence of different categories of constraints where the functional influence of the information provided is dependent on the motor output.
AT the recent China National Cliff Climbing Invitational Tournament, I first came to know Yang Lihong, the cliff climber. Her well-proportioned figure demonstrates a powerful explosive force attacking the surface. She sticks firmly to the rock as her limbs move rhythmically in search of new support points. Her black ponytail waves with every forceful movement of her body. Rock climbing is relatively new as a
Garrison, Joe; And Others
As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized instructional units in the area of air conditioning. The instructional units focus on air conditioning fundamentals, window air conditioning, system and installation, troubleshooting and…
Snow, Rufus; And Others
As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized instructional units in the area of refrigeration. The instructional units focus on refrigeration fundamentals, tubing and pipe, refrigerants, troubleshooting, window air conditioning, and…
Terry, Dorothy Givens
Dr. Mae Jemison is the world's first woman astronaut of color who continues to reach for the stars. Jemison was recently successful in leading a team that has secured a $500,000 federal grant to make interstellar space travel a reality. The Dorothy Jemison Foundation for Excellence (named after Jemison's mother) was selected in June by the Defense…
note onsets and short interaction times between player and instrument do not allow for much adjustment once a stroke is initiated. The paper surveys research that shows a close relationship between movement and sound production, and how playing conditions such as tempo and the rebound after impact...... affect the movements. Furthermore, I discuss differences in movement organization, and visual information from striking movements....
Hu, Xiaogang; Newell, Karl M
This study investigated the coordination and control strategies that the elderly adopt during a redundant finger force coordination task and how the amount of visual information regulates the coordination patterns. Three age groups (20-24, 65-69, and 75-79 yr) performed a bimanual asymmetric force task. Task asymmetry was manipulated via imposing different coefficients on the finger forces such that the weighted sum of the two index finger forces equaled the total force. The amount of visual information was manipulated by changing the visual information gain of the total force output. Two hypotheses were tested: the reduced adaptability hypothesis predicts that the elderly show less degree of force asymmetry between hands compared with young adults in the asymmetric coefficient conditions, whereas the compensatory hypothesis predicts that the elderly exhibit more asymmetric force coordination patterns with asymmetric coefficients. Under the compensatory hypothesis, two contrasting directions of force sharing strategies (i.e., more efficient coordination strategy and minimum variance strategy) are expected. A deteriorated task performance (high performance error and force variability) was found in the two elderly groups, but enhanced visual information improved the task performance in all age groups. With low visual information gain, the elderly showed reduced adaptability (i.e., less asymmetric forces between hands) to the unequal weighting coefficients, which supported the reduced adaptability hypothesis; however, the elderly revealed the same degree of adaptation as the young group under high visual gain. The findings are consistent with the notion that the age-related reorganization of force coordination and control patterns is mediated by visual information and, more generally, the interactive influence of multiple categories of constraints.
Rolfs, Martin; Lawrence, Bonnie M; Carrasco, Marisa
We investigated the impact of the preparation of reach movements on visual perception by simultaneously quantifying both an objective measure of visual sensitivity and the subjective experience of apparent contrast. Using a two-by-two alternative forced choice task, observers compared the orientation (clockwise or counterclockwise) and the contrast (higher or lower) of a Standard Gabor and a Test Gabor, the latter of which was presented during reach preparation, at the reach target location or the opposite location. Discrimination performance was better overall at the reach target than at the opposite location. Perceived contrast increased continuously at the target relative to the opposite location during reach preparation, that is, after the onset of the cue indicating the reach target. The finding that performance and appearance do not evolve in parallel during reach preparation points to a distinction with saccade preparation, for which we have shown previously there is a parallel temporal evolution of performance and appearance. Yet akin to saccade preparation, this study reveals that overall reach preparation enhances both visual performance and appearance.
Barlaam, F; Fortin, C; Vaugoyeau, M; Schmitz, C; Assaiante, C
The aim of this study was to explore, during adolescence, alterations in the use of a sensori-motor representation as unveiled by the measurement of anticipatory postural control in a bimanual load-lifting task. We hypothesised that adolescence constitutes a period of refinement of anticipatory postural control due to on-going updates of the body schema and sensori-motor representations. The anticipatory postural control was assessed using a bimanual load-lifting paradigm in which subjects stabilise their left postural forearm, which is supporting an object, while they use their right hand to lift up the object. Kinematics and electromyographic data were recorded in two groups of adolescents (11-13 and 14-16 years of age) and a group of adults. Age and gender effects were tested. During voluntary unloading, the postural forearm stabilisation in adolescents was still different from the adult one, suggesting that further improvement of the postural forearm stabilisation must take place after the age of 16. No differences occur in the two adolescent groups. Moreover, girls presented a better stabilisation of the postural forearm than boys, indicating an earlier refinement of anticipatory postural control. The decrease of activity over postural flexors, which ensure postural stabilisation, appeared later in adolescents with respect to adults. Delayed timing adjustments and increased variability could reflect intense developmental processes underlain by an intense period of CNS maturation during adolescence. We discuss the role of brain maturation in the refinement of sensori-motor representations and the update of body schema.
Greaves, Susan; Imms, Christine; Krumlinde-Sundholm, Lena; Dodd, Karen; Eliasson, Ann-Christin
Toys that provoke the use of both hands are required to develop a test of bimanual performance in children 8-18 months with unilateral cerebral palsy (Mini-AHA). To choose the toys, a conceptual model based on perception-action theory and object use was used to guide a literature review. Evidence was sought for three critical relationships…
The creation of the world's largest sandstone cavern, not a small feat! At the bottom, cave-in preventing steel mesh can be seen clinging to the top of the tunnel. The digging of UX-15, the cavern that will house ATLAS, reached the upper ceiling of LEP on October 10th. The breakthrough which took place nearly 100 metres underground occurred precisely on schedule and exactly as planned. But much caution was taken beforehand to make the LEP breakthrough clean and safe. To prevent the possibility of cave-ins in the side tunnels that will eventually be attached to the completed UX-15 cavern, reinforcing steel mesh was fixed into the walls with bolts. Obviously no people were allowed in the LEP tunnels below UX-15 as the breakthrough occurred. The area was completely evacuated and fences were put into place to keep all personnel out. However, while personnel were being kept out of the tunnels below, this has been anything but the case for the work taking place up above. With the creation of the world's largest...
Stereotypic movements are repetitive patterns of movement with certain peculiar features that make them especially interesting. Their physiopathology and their relationship with the neurobehavioural disorders they are frequently associated with are unknown. In this paper our aim is to offer a simple analysis of their dominant characteristics, their differentiation from other processes and a hypothesis of the properties of stereotypic movements, which could all set the foundations for research work into their physiopathology.
Effects of target location and uncertainty on reaching movements in standing position Los efectos de la ubicación de la diana y la incertidumbre en los movimientos de alcance en la posición vertical Efeitos da localização do alvo e da incerteza em movimentos de alcance na postura ereta
Luiz de França Bahia Loureiro Junior
Full Text Available The effects of target location and uncertainty of target position on reaching movements while standing were investigated. Ten healthy, right-handed adults stood facing a 17'' touchscreen. They were instructed to press with their right index fingertip a push bottom and touch the center of the target displayed on the screen after it was lighted on, moving quickly their arm. The target was shown either ipsi- or contralateral to the right arm and either in a certain or uncertain position. Reaction time (RT, movement time (MT, and radial error (RE were assessed. Results revealed shorter RT (≈ 35 ms and smaller RE (≈ 0.19 cm for certain than for uncertain condition and slightly longer RT (≈ 8 ms and MT (≈ 18 ms for reaches towards the contralateral target. In conclusion, the findings of this study showing the effect of uncertainty of target location as well as target position are also applied to arm reaching in standing position.Los efectos de la ubicación de la diana y la incertidumbre acerca de la posición de la diana en los movimientos de alcance fueron investigados. Diez adultos sanos y diestros estaban frente a una pantalla táctil de 17''. Se les instruyó para presionar un interruptor con el dedo índice derecho y tocar el centro de la diana que aparece en la pantalla después de haber sido iluminado, moviéndo rápidamente su miembro superior. La diana fue mostrada ya sea ipsi o contralateralmente y los participantes tenían o no certidumbre sobre la posición de la misma. El tiempo de reacción (TR, el tiempo de movimiento (TM, y el error radial (ER fueron evaluados. Los resultados revelaron ser más cortos TR (≈ 35 ms y RE menor (≈ 0,19cm en la condición de certeza y mayores TR (≈ 8 ms y TM (≈ 18 ms en los movimientos hacia la meta contralateral. En conclusión, los hallazgos de este estudio que muestra los efectos de la incertidumbre de la ubicación de la diana, así como la posición de la diana se aplican también a
A survey of 26 Rorschach experts and 19 students of Rorschach use was conducted to help students using the Exner Comprehensive System determine whether to code movement for nouns with definitions that include movement. Experts and students did not reach agreement, but a literature review suggests such nouns should often be coded as movement. (SLD)
Meguerditchian, Adrien; Vauclair, Jacques; Hopkins, William D
Within the evolutionary framework about the origin of human handedness and hemispheric specialization for language, the question of expression of population-level manual biases in nonhuman primates and their potential continuities with humans remains controversial. Nevertheless, there is a growing body of evidence showing consistent population-level handedness particularly for complex manual behaviors in both monkeys and apes. In the present article, within a large comparative approach among primates, we will review our contribution to the field and the handedness literature related to two particular sophisticated manual behaviors regarding their potential and specific implications for the origins of hemispheric specialization in humans: bimanual coordinated actions and gestural communication. Whereas bimanual coordinated actions seem to elicit predominance of left-handedness in arboreal primates and of right-handedness in terrestrial primates, all handedness studies that have investigated gestural communication in several primate species have reported stronger degree of population-level right-handedness compared to noncommunicative actions. Communicative gestures and bimanual actions seem to affect differently manual asymmetries in both human and nonhuman primates and to be related to different lateralized brain substrates. We will discuss (1) how the data of hand preferences for bimanual coordinated actions highlight the role of ecological factors in the evolution of handedness and provide additional support the postural origin theory of handedness proposed by MacNeilage [MacNeilage . Present status of the postural origins theory. In W. D. Hopkins (Ed.), The evolution of hemispheric specialization in primates (pp. 59-91). London: Elsevier/Academic Press] and (2) the hypothesis that the emergence of gestural communication might have affected lateralization in our ancestor and may constitute the precursors of the hemispheric specialization for language.
Heed, Tobias; Möller, Johanna; Röder, Brigitte
To localize touch, the brain integrates spatial information coded in anatomically based and external spatial reference frames. Sighted humans, by default, use both reference frames in tactile localization. In contrast, congenitally blind individuals have been reported to rely exclusively on anatomical coordinates, suggesting a crucial role of the visual system for tactile spatial processing. We tested whether the use of external spatial information in touch can, alternatively, be induced by a movement context. Sighted and congenitally blind humans performed a tactile temporal order judgment task that indexes the use of external coordinates for tactile localization, while they executed bimanual arm movements with uncrossed and crossed start and end postures. In the sighted, start posture and planned end posture of the arm movement modulated tactile localization for stimuli presented before and during movement, indicating automatic, external recoding of touch. Contrary to previous findings, tactile localization of congenitally blind participants, too, was affected by external coordinates, though only for stimuli presented before movement start. Furthermore, only the movement's start posture, but not the planned end posture affected blind individuals' tactile performance. Thus, integration of external coordinates in touch is established without vision, though more selectively than when vision has developed normally, and possibly restricted to movement contexts. The lack of modulation by the planned posture in congenitally blind participants suggests that external coordinates in this group are not mediated by motor efference copy. Instead the task-related frequent posture changes, that is, movement consequences rather than planning, appear to have induced their use of external coordinates.
Full Text Available The neurobiology of reaching has been extensively studied in human and non-human primates. However, the mechanisms that allow a subject to decide-without engaging in explicit action-whether an object is reachable are not fully understood. Some studies conclude that decisions near the reach limit depend on motor simulations of the reaching movement. Others have shown that the body schema plays a role in explicit and implicit distance estimation, especially after motor practice with a tool. In this study we evaluate the causal role of multisensory body representations in the perception of reachable space. We reasoned that if body schema is used to estimate reach, an illusion of the finger size induced by proprioceptive stimulation should propagate to the perception of reaching distances. To test this hypothesis we induced a proprioceptive illusion of extension or shrinkage of the right index finger while participants judged a series of LEDs as reachable or non-reachable without actual movement. Our results show that reach distance estimation depends on the illusory perceived size of the finger: illusory elongation produced a shift of reaching distance away from the body whereas illusory shrinkage produced the opposite effect. Combining these results with previous findings, we suggest that deciding if a target is reachable requires an integration of body inputs in high order multisensory parietal areas that engage in movement simulations through connections with frontal premotor areas.
Petroni, Agustin; Carbajal, M. Julia; Sigman, Mariano
The neurobiology of reaching has been extensively studied in human and non-human primates. However, the mechanisms that allow a subject to decide—without engaging in explicit action—whether an object is reachable are not fully understood. Some studies conclude that decisions near the reach limit depend on motor simulations of the reaching movement. Others have shown that the body schema plays a role in explicit and implicit distance estimation, especially after motor practice with a tool. In this study we evaluate the causal role of multisensory body representations in the perception of reachable space. We reasoned that if body schema is used to estimate reach, an illusion of the finger size induced by proprioceptive stimulation should propagate to the perception of reaching distances. To test this hypothesis we induced a proprioceptive illusion of extension or shrinkage of the right index finger while participants judged a series of LEDs as reachable or non-reachable without actual movement. Our results show that reach distance estimation depends on the illusory perceived size of the finger: illusory elongation produced a shift of reaching distance away from the body whereas illusory shrinkage produced the opposite effect. Combining these results with previous findings, we suggest that deciding if a target is reachable requires an integration of body inputs in high order multisensory parietal areas that engage in movement simulations through connections with frontal premotor areas. PMID:26110274
Torres Elizabeth B
Full Text Available Abstract Background Movement regularities are inherently present in automated goal-directed motions of the primate's arm system. They can provide important signatures of intentional behaviours driven by sensory-motor strategies, but it remains unknown if during motor learning new regularities can be uncovered despite high variability in the temporal dynamics of the hand motions. Methods We investigated the conservation and violation of new movement regularity obtained from the hand motions traced by two untrained monkeys as they learned to reach outwardly towards spatial targets while avoiding obstacles in the dark. The regularity pertains to the transformation from postural to hand paths that aim at visual goals. Results In length-minimizing curves the area enclosed between the Euclidean straight line and the curve up to its point of maximum curvature is 1/2 of the total area. Similar trend is found if one examines the perimeter. This new movement regularity remained robust to striking changes in arm dynamics that gave rise to changes in the speed of the reach, to changes in the hand path curvature, and to changes in the arm's postural paths. The area and perimeter ratios characterizing the regularity co-varied across repeats of randomly presented targets whenever the transformation from posture to hand paths was compliant with the intended goals. To interpret this conservation and the cases in which the regularity was violated and recovered, we provide a geometric model that characterizes arm-to-hand and hand-to-arm motion paths as length minimizing curves (geodesics in a non-Euclidean space. Whenever the transformation from one space to the other is distance-metric preserving (isometric the two symmetric ratios co-vary. Otherwise, the symmetric ratios and their co-variation are violated. As predicted by the model we found empirical evidence for the violation of this movement regularity whenever the intended goals mismatched the actions. This
Van Der Heide, JC; Folk, JM; Otten, B; Stremmelaar, E; Hadders-Algra, M
The relationships between kinematic characteristics of sitting posture during reaching movements of the dominant arm and I) the kinematics of the reaching movement itself and 2) functional performance during daily life activities (PEDI) were assessed in 51 sitting preterm children with cerebral pals
Zbib, Basel; Henriques, Denise Y P; Cressman, Erin K
When subjects reach in a novel visuomotor environment (e.g. while viewing a cursor representing their hand that is rotated from their hand's actual position), they typically adjust their movements (i.e. bring the cursor to the target), thus reducing reaching errors. Additionally, research has shown that reaching with altered visual feedback of the hand results in sensory changes, such that proprioceptive estimates of hand position are shifted in the direction of the visual feedback experienced (Cressman and Henriques in J Neurophysiol 102:3505-3518, 2009). This study looked to establish the time course of these sensory changes. Additionally, the time courses of implicit sensory and motor changes were compared. Subjects reached to a single visual target while seeing a cursor that was either aligned with their hand position (50 trials) or rotated 30° clockwise relative to their hand (150 trials). Reach errors and proprioceptive estimates of felt hand position were assessed following the aligned reach training trials and at seven different times during the rotated reach training trials by having subjects reach to the target without visual feedback, and provide estimates of their hand relative to a visual reference marker, respectively. Results revealed a shift in proprioceptive estimates throughout the rotated reach training trials; however, significant sensory changes were not observed until after 70 trials. In contrast, results showed a greater change in reaches after a limited number of reach training trials with the rotated cursor. These findings suggest that proprioceptive recalibration arises more slowly than reach adaptation.
Kawashima, Noritaka; Mita, Tomoki
A phantom limb is the sensation that an amputated limb is still attached to the body and is moving together with other body parts. Phantom limb phenomenon is often described on the basis of the patient's subjective sense, for example as represented using a visual analog scale (VAS). The aim of this study was to propose a novel quantification method for behavioral aspect of phantom limb by psychophysics. Twelve unilateral forearm amputees were asked to perform phantom wrist motion with various motion frequencies (60, 80, 100, 120, 140, 160, 180, 200, 220, 240% of preferred speed). The attainment of phantom limb motion in each session was rated by the VAS ranging from 0 (hard) to 10 (easy). The relationship between the VAS and motion frequency was mathematically fitted by quadric function, and the value of shift and the degree of steepness were obtained as evaluation variables for the phantom limb movement. In order to test whether the proposed method can reasonably quantify the characteristics of phantom limb motion, we compared the variables among three different phantom limb movement conditions: (1) unilateral (phantom only), (2) bimanual, and (3) bimanual wrist movement with mirror reflection-induced visual feedback (MVF). While VAS rating showed a larger extent of inter- and intra-subject variability, the relationship of the VAS in response to motion frequency could be fitted by quadric curve, and the obtained parameters based on quadric function well characterize task-dependent changes in phantom limb movement. The present results suggest the potential usefulness of psychophysical evaluation as a validate assessment tool of phantom limb condition.
Full Text Available A phantom limb is the sensation that an amputated limb is still attached to the body and is moving together with other body parts. Phantom limb phenomenon is often described on the basis of the patient's subjective sense, for example as represented using a visual analog scale (VAS. The aim of this study was to propose a novel quantification method for behavioral aspect of phantom limb by psychophysics. Twelve unilateral forearm amputees were asked to perform phantom wrist motion with various motion frequencies (60, 80, 100, 120, 140, 160, 180, 200, 220, 240% of preferred speed. The attainment of phantom limb motion in each session was rated by the VAS ranging from 0 (hard to 10 (easy. The relationship between the VAS and motion frequency was mathematically fitted by quadric function, and the value of shift and the degree of steepness were obtained as evaluation variables for the phantom limb movement. In order to test whether the proposed method can reasonably quantify the characteristics of phantom limb motion, we compared the variables among three different phantom limb movement conditions: (1 unilateral (phantom only, (2 bimanual, and (3 bimanual wrist movement with mirror reflection-induced visual feedback (MVF. While VAS rating showed a larger extent of inter- and intra-subject variability, the relationship of the VAS in response to motion frequency could be fitted by quadric curve, and the obtained parameters based on quadric function well characterize task-dependent changes in phantom limb movement. The present results suggest the potential usefulness of psychophysical evaluation as a validate assessment tool of phantom limb condition.
Mixed Movements is a research project engaged in performance-based architectural drawing. Architectonic implementation questions relations between the human body and a body of architecture by the different ways we handle drawing materials. A drawing may explore architectonic problems at other...... levels than those related to building, and this exploration is a special challenge and competence implicit artistic development work. The project Mixed Movements generates drawing-material, not primary as representation, but as a performance-based media, making the body being-in-the-media felt and appear...... as possible operational moves....
Full Text Available Abstract Background A mechanism that monitors the congruence between sensory inputs and motor outputs is necessary to control voluntary movement. The representation of limb position is constantly updated on the basis of somatosensory and visual information and efference copy from motor areas. However, the cortical mechanism underlying detection of limb position using somatosensory and visual information has not been elucidated. This study investigated the influence of visual feedback on information processing in somatosensory areas during movement execution using magnetoencephalography. We used an experimental condition in which the visual information was incongruent despite the motor execution and somatosensory feedback being congruent. Subjects performed self-paced bimanual movements of both thumbs, either symmetric or asymmetric, under normal visual and mirrored conditions. The mirror condition provided a visual feedback by showing a reflection of the subject’s right hand in place of the left hand. Therefore, in the Asymmetric task of the Mirror condition, subjects saw symmetric movements despite performing asymmetric movements. Results Activation in the primary somatosensory area (SI revealed inhibition of neural activity and that in the secondary somatosensory area (SII showed enhancement with voluntary movement. In addition, the SII contralateral to the side of stimulation was significantly enhanced in the Asymmetric task of the Mirror condition, which provided non-veridical visual feedback. Conclusions These results suggested that visual information influenced the neuronal activity concerning sensorimotor interaction in the SII during motor execution. The SII contributes to the detection of unpredicted visual feedback of movement execution.
Full Text Available In developing a shoulder prosthesis, in addition to appropriate payload and range of motion under the constraints of weight and shape, impact absorption is very important for safe use. Hybridization of two different actuators (pneumatic elastic actuators with the features of lightness and intrinsic visco-elasticity, and servo motors that have stable torque and a large range of motion in combination with an antagonistic mechanism was employed to achieve the development of the shoulder prosthesis. A two-link, two-degree-of-freedom arm was used to test the different hybridization configurations in order to investigate the impact absorption. A dynamic simulation platform based on four bimanual activities of daily living was established to obtain the required range of motion and torque for joints of a two-link, four-degree-of-freedom arm. The number of pneumatic elastic actuators required and the dimension of the antagonistic mechanism mechanical structures were optimized using the dynamic simulation platform. The best configuration of the two types of actuators was determined using the dynamic simulation based on the impact absorption results and other criteria. Moreover, a simplified prototype driven by hybrid actuation was made. It was shown that the pneumatic elastic actuator joint could improve impact absorption, and the actuator configuration of shoulder prostheses is activity of daily living dependent. The prototype could reproduce a certain activity of daily living motion, indicating its feasibility in daily living.
Rai Harminder K
Full Text Available Abstract Background The prerequisites for a good capsulorhexis include a deep, well maintained anterior chamber, globe stabilization and globe manipulation. This helps to achieve a capsulorhexis of optimal size, shape and obtain the best possible position for a red glow under retroillumination. We report the use of irrigation handpiece of bimanual irrigation aspiration system to stabilize the globe, maintain a deep anterior chamber and manipulate the globe to a position of optimal red reflex during needle capsulorhexis in phacoemulsification. Methods Two side ports are made with 20 G MVR 'V' lance knife (Alcon, USA. The irrigation handpiece with irrigation on is introduced into the anterior chamber through one side port and the 26-G cystitome (made from 26-G needle is introduced through the other. The capsolurhexis is completed with the needle. Results Needle capsulorhexis with this technique was used in 30 cases of uncomplicated immature senile cataracts. 10 cases were done under peribulbar anaesthesia and 20 under topical anaesthesia. A complete capsulorhexis was achieved in all cases. Conclusion The irrigating handpiece maintains deep anterior chamber, stabilizes the globe, facilitates pupillary dilatation, and helps in maintaining the eye in the position with optimal red reflex during needle capsulorhexis. This technique is a safe and effective way to perform needle capsulorhexis.
Cohn, J V; DiZio, P; Lackner, J R
Subjects who are in an enclosed chamber rotating at constant velocity feel physically stationary but make errors when pointing to targets. Reaching paths and endpoints are deviated in the direction of the transient inertial Coriolis forces generated by their arm movements. By contrast, reaching movements made during natural, voluntary torso rotation seem to be accurate, and subjects are unaware of the Coriolis forces generated by their movements. This pattern suggests that the motor plan for reaching movements uses a representation of body motion to prepare compensations for impending self-generated accelerative loads on the arm. If so, stationary subjects who are experiencing illusory self-rotation should make reaching errors when pointing to a target. These errors should be in the direction opposite the Coriolis accelerations their arm movements would generate if they were actually rotating. To determine whether such compensations exist, we had subjects in four experiments make visually open-loop reaches to targets while they were experiencing compelling illusory self-rotation and displacement induced by rotation of a complex, natural visual scene. The paths and endpoints of their initial reaching movements were significantly displaced leftward during counterclockwise illusory rotary displacement and rightward during clockwise illusory self-displacement. Subjects reached in a curvilinear path to the wrong place. These reaching errors were opposite in direction to the Coriolis forces that would have been generated by their arm movements during actual torso rotation. The magnitude of path curvature and endpoint errors increased as the speed of illusory self-rotation increased. In successive reaches, movement paths became straighter and endpoints more accurate despite the absence of visual error feedback or tactile feedback about target location. When subjects were again presented a stationary scene, their initial reaches were indistinguishable from pre
Chloroplast movement is important for plant survival under high light and for efficient photosynthesis under low light. This review introduces recent knowledge on chloroplast movement and shows how to analyze the responses and the moving mechanisms, potentially inspiring research in this field. Avoidance from the strong light is mediated by blue light receptor phototropin 2 (phot2) plausibly localized on the chloroplast envelop and accumulation at the week light-irradiated area is mediated by phot1 and phot2 localized on the plasma membrane. Chloroplasts move by chloroplast actin (cp-actin) filaments that must be polymerized by Chloroplast Unusual Positioning1 (CHUP1) at the front side of moving chloroplast. To understand the signal transduction pathways and the mechanism of chloroplast movement, that is, from light capture to motive force-generating mechanism, various methods should be employed based on the various aspects. Observation of chloroplast distribution pattern under different light condition by fixed cell sectioning is somewhat an old-fashioned technique but the most basic and important way. However, most importantly, precise chloroplast behavior during and just after the induction of chloroplast movement by partial cell irradiation using an irradiator with either low light or strong light microbeam should be recorded by time lapse photographs under infrared light and analyzed. Recently various factors involved in chloroplast movement, such as cp-actin filaments and CHUP1, could be traced in Arabidopsis transgenic lines with fluorescent protein tags under a confocal laser scanning microscope (CLSM) and/or a total internal reflection fluorescence microscope (TIRFM). These methods are listed and their advantages and disadvantages are evaluated.
ABOUT THE BOOK Halo Reach is the latest installment, and goes back to Halo's roots in more ways than one. Set around one of the most frequently referenced events in the Haloverse-The Fall of Reach-Reach puts you in the shoes of Noble 6, an unnamed Spartan, fighting a doomed battle to save the planet. Dual-wielding's gone, health is back, and equipment now takes the form of different "classes," with different weapon loadouts and special abilities (such as sprinting, cloaking, or flight). If you're reading this guide, you're either new to the Halo franchise and looking to get a leg up on all
Cornelsen, Sonja; Rennig, Johannes; Himmelbach, Marc
The two-visual-systems hypothesis (TVSH) postulates that memory-guided movements rely on intact functions of the ventral stream. Its particular importance for memory-guided actions was initially inferred from behavioral dissociations in the well-known patient DF. Despite of rather accurate reaching and grasping movements to visible targets, she demonstrated grossly impaired memory-guided grasping as much as impaired memory-guided reaching. These dissociations were later complemented by apparently reversed dissociations in patients with dorsal damage and optic ataxia. However, grasping studies in DF and optic ataxia patients differed with respect to the retinotopic position of target objects, questioning the interpretation of the respective findings as a double dissociation. In contrast, the findings for reaching errors in both types of patients came from similar peripheral target presentations. However, new data on brain structural changes and visuomotor deficits in DF also questioned the validity of a double dissociation in reaching. A severe visuospatial short-term memory deficit in DF further questioned the specificity of her memory-guided reaching deficit. Therefore, we compared movement accuracy in visually-guided and memory-guided reaching in a new patient who suffered a confined unilateral damage to the ventral visual system due to stroke. Our results indeed support previous descriptions of memory-guided movements' inaccuracies in DF. Furthermore, our data suggest that recently discovered optic-ataxia like misreaching in DF is most likely caused by her parieto-occipital and not by her ventral stream damage. Finally, multiple visuospatial memory measurements in HWS suggest that inaccuracies in memory-guided reaching tasks in patients with ventral damage cannot be explained by visuospatial short-term memory or perceptual deficits, but by a specific deficit in visuomotor processing.
Hadders-Algra, M; van der Fits, IBM; Stremmelaar, EF; Touwen, BCL
The development of postural adjustments during reaching movements was longitudinally studied in seven infants with cerebral palsy (CP) between 4 and 18 months of age. Five infants developed spastic hemiplegia, one spastic tetraplegia, and one spastic tetraplegia with athetosis. Each assessment consi
@@ China's second lunar probe, Chang'e-2, has reached an orbit 1.5 million kilometers from Earth for an additional mission of deep space exploration, the State Administration for Science, Technology and Industry for National Defense announced.
Full Text Available Abstract Background How the central nervous system (CNS organizes the joint dynamics for multi-joint movement is a complex problem, because of the passive interaction among segmental movements. Previous studies have demonstrated that the CNS predictively compensates for interaction torque (INT which is arising from the movement of the adjacent joints. However, most of these studies have mainly examined quick movements, presumably because the current belief is that the effects of INT are not significant at slow speeds. The functional contribution of INT for multijoint movements performed in various speeds is still unclear. The purpose of this study was to examine the contribution of INT to a planer reaching in a wide range of motion speeds for healthy subjects. Methods Subjects performed reaching movements toward five targets under three different speed conditions. Joint position data were recorded using a 3-D motion analysis device (50 Hz. Torque components, muscle torque (MUS, interaction torque (INT, gravity torque (G, and net torque (NET were calculated by solving the dynamic equations for the shoulder and elbow. NET at a joint which produces the joint kinematics will be an algebraic sum of torque components; NET = MUS - G - INT. Dynamic muscle torque (DMUS = MUS-G was also calculated. Contributions of INT impulse and DMUS impulse to NET impulse were examined. Results The relative contribution of INT to NET was not dependent on speed for both joints at every target. INT was additive (same direction to DMUS at the shoulder joint, while in the elbow DMUS counteracted (opposed to INT. The trajectory of reach was linear and two-joint movements were coordinated with a specific combination at each target, regardless of motion speed. However, DMUS at the elbow was opposed to the direction of elbow movement, and its magnitude varied from trial to trial in order to compensate for the variability of INT. Conclusion Interaction torque was important at
Full Text Available In 1984 Christopher Cordner offered a critical view on theories of graceful movement in sport developed by Ng. G. Wulk, David Best and Joseph Kupfer. In 2001 Paul Davis criticized his view. Cordner responded, rejecting all the criticism. More than a century before, Herbert Spencer and Jean-Marie Guyau had a similar controversy over grace. Both exchanges of opinion involve three positions: that grace is the most efficient movement and therefore something quantitative and measurable; that grace is expression of the wholeness of person and the world; and that grace is something which neither science nor philosophy can explain. To clarify these conflicting issues, this article proposes to examine the history of the notion which goes back to the Latin gratia and has root in the Ancient Greek charis, and to apply the concepts of cultural anchor and thin coherence, following John R. Searle’s explanation that we produce epistemically objective accounts of ontologically subjective reality.
Lee, Young Hee; Im, Jaeg Yeong
This book is for antinuclear movement. So, this book introduces many articles on nuclear issues of Asia and the pacific area. The titles of articles are the crusades of Reagan by Werner Plaha, contending between super powers in Europe by Alva Reimer Myrdal, claims of resistance by Daniel Ellsberg, nuclear and the Korean Peninsula by Go, Seung Woo, Liberation but of belief of nuclear weapon by Lee, Young Hee and nuclear weapon in Korea by peter Haze.
Wilmut, Kate; Byrne, Maia; Barnett, Anna L.
When picking up an object, adults show a longer deceleration phase when the onward action has a greater precision requirement. Tailoring action in this way is thought to need forward modelling in order to predict the consequences of movement. Some evidence suggests that young children also tailor reaching in this way; however, how this skill…
Tallet, Jessica; Albaret, Jean-Michel; Barral, Jérôme
The present study investigates developmental changes in selective inhibition of symmetric movements with a lateralized switching task from bimanual to unimanual tapping in typically developing (TD) children and with Developmental Coordination Disorder (DCD) from 7 to 10 years old. Twelve right-handed TD children and twelve gender-matched children with DCD and probable DCD produce a motor switching task in which they have (1) to synchronize with the beat of an auditory metronome to produce bimanual symmetrical tapping and (2) to selectively inhibit their left finger's tapping while continuing their right finger's tapping and conversely. We assess (1) the development of the capacity to inhibit the stopping finger (number of supplementary taps after the stopping instruction) and (2) the development of the capacity to maintain the continuing finger (changes in the mean tempo and its variability for the continuing finger's tapping) and (3) the evolution of performance through trials. Results indicate that (1) TD children present an age-related increase in the capacity to inhibit and to maintain the left finger's tapping, (2) DCD exhibits persistent difficulties to inhibit the left finger's tapping, and (3) both groups improve their capacity to inhibit the left finger's movements through trials. In conclusion, the lateralized switching task provides a simple and fine tool to reveal differences in selective inhibition of symmetric movements in TD children and children with DCD. More theoretically, the specific improvement in selective inhibition of the left finger suggests a progressive development of inter-hemispheric communication during typical development that is absent or delayed in children with DCD.
Full Text Available BACKGROUND: Human movement can be guided automatically (implicit control or attentively (explicit control. Explicit control may be engaged when learning a new movement, while implicit control enables simultaneous execution of multiple actions. Explicit and implicit control can often be assigned arbitrarily: we can simultaneously drive a car and tune the radio, seamlessly allocating implicit or explicit control to either action. This flexibility suggests that sensorimotor signals, including those that encode spatially overlapping perception and behavior, can be accurately segregated to explicit and implicit control processes. METHODOLOGY/PRINCIPAL FINDINGS: We tested human subjects' ability to segregate sensorimotor signals to parallel control processes by requiring dual (explicit and implicit control of the same reaching movement and testing for interference between these processes. Healthy control subjects were able to engage dual explicit and implicit motor control without degradation of performance compared to explicit or implicit control alone. We then asked whether segregation of explicit and implicit motor control can be selectively disrupted by studying dual-control performance in subjects with no clinically manifest neurologic deficits in the presymptomatic stage of Huntington's disease (HD. These subjects performed successfully under either explicit or implicit control alone, but were impaired in the dual-control condition. CONCLUSION/SIGNIFICANCE: The human nervous system can exert dual control on a single action, and is therefore able to accurately segregate sensorimotor signals to explicit and implicit control. The impairment observed in the presymptomatic stage of HD points to a possible crucial contribution of the striatum to the segregation of sensorimotor signals to multiple control processes.
Successful reaching requires postural control, either by active regulation or by postural support. The present paper reviews literature on typical and atypical development of reaching and postural control during infancy. Typically, reaching movements end in grasping around 4 months of age. Initially
This SpringerBrief discusses the characteristics of spatiotemporal movement data, including uncertainty and scale. It investigates three core aspects of Computational Movement Analysis: Conceptual modeling of movement and movement spaces, spatiotemporal analysis methods aiming at a better understanding of movement processes (with a focus on data mining for movement patterns), and using decentralized spatial computing methods in movement analysis. The author presents Computational Movement Analysis as an interdisciplinary umbrella for analyzing movement processes with methods from a range of fi
AIM: We compared bimanual microincision cataract surgery (MICS) and standard coaxial phacoemulsification (CAP) in terms of uncorrected visual acuity (UCVA) recorded 1 h and 2 weeks postoperatively. METHODS: This was a prospective, nonrandomised comparative study. All MICS procedures were performed by one surgeon (MGM), and all CAP procedures were performed by another surgeon (SB). Eyes with visually consequential ocular morbidity were excluded. The primary outcome measure was UCVA recorded 1 h postoperatively. RESULTS: One hundred eyes underwent MICS and CAP (50 eyes in each group). The treatment groups did not differ significantly in terms of preoperative mean best corrected visual acuity (6\\/24 +\\/- 4.3 lines and 6\\/20 +\\/- 4.4 lines in the MICS and the CAP groups, respectively; P = 0.65). Also, there was no significant difference in terms of postoperative UCVA at 1 h or at 2 weeks (mean +\\/- standard deviation UCVA 1 h postoperatively: MICS: 6\\/36 +\\/- 5.7 lines; CAP: 6\\/30 +\\/- 4.7 lines; P = 0.80; UCVA 2 weeks postoperatively: MICS: 6\\/10 +\\/- 1.9 lines; CAP: 6\\/10 +\\/- 2.2 lines; P = 0.90). However, nine eyes (18%) and one eye (2%) achieved a UCVA of C6\\/12 at 1 h following MICS and CAP, respectively, and this difference was statistically significant (P = 0.02). CONCLUSION: Mean UCVA at 1 h and at 2 weeks following cataract surgery was not significantly different between eyes undergoing MICS and CAP. However, a greater proportion of patients achieved a UCVA of C6\\/12 following MICS when compared with CAP.
J. de Haan; W.P. Knulst
Original title: Het bereik van de kunsten. The reach of the arts (Het bereik van de kunsten) is the fourth study in a series which periodically analyses the status of cultural participation, reading and use of other media. The series, Support for culture (Het culturele draagvlak) is sponsored by th
Fernanda P. S. Silva
whether these adjustments change in older infants. OBJECTIVES: The aim of this study was to determine whether the size and rigidity of objects influence the proximal and distal adjustments to reaching of infants of 6, 7, 8 and 36 months of age. METHODS: Nine healthy infants were presented with: one large rigid, one small rigid, one large malleable and one small malleable object. The movements were videotaped and later analyzed qualitatively with regard to proximal (unimanual and bimanual reaching and distal adjustments (horizontal, vertical and oblique hand orientation, opened, half-open and closed hand and with regard to grasping of these objects (with and without. Friedman test and Dunn multiple comparisons were applied and 0.05 was considered as a significant difference. RESULTS: Infants of 36 months of age performed more unimanual reaching than younger infants. Additionally, at all ages, unimanual reaching was particularly performed for small objects. At 36 months of age infants guided the hand horizontally to touch and grasp the objects, while at 6 and 7 months the hand orientation was oblique to touch and vertical to grasp the objects, regardless of the object's properties. Over the months, both at the beginning and at the end of reaching, the hands became more open, especially to touch the large rigid object, and infants increasingly performed reaching with successful grasping, especially for malleable or small objects. CONCLUSIONS: From 6 to 36 months of age, the reaching became more refined and the infants adjusted to the different properties of the objects which were observed through changes in the proximal and distal adjustments.
Full Text Available This article acknowledges the need for Church Planting Movements among the unreached peoples of India. Of particular concern to this study is the application of Church Planting Movement strategy to forward caste Hindus of India. It is shown that evangelizing households (family or �oikos� evangelism is a New Testament strategy and the most appropriate strategy for reaching forward caste Hindus. It is concluded that Christian disciples remaining within Hindu culture and familial systems hold the potential for the most indigenous approach to evangelizing forward caste Hindus.
Freudenburg, William R.
Rather than seeking ivory-tower isolation, members of the Rural Sociological Society have always been distinguished by a willingness to work with specialists from a broad range of disciplines, and to work on some of the world's most challenging problems. What is less commonly recognized is that the willingness to reach beyond disciplinary…
Juravle, Georgiana; McGlone, Francis; Spence, Charles
Tactile perception is inhibited during movement execution, a phenomenon known as tactile suppression. Here, we investigated whether the type of movement determines whether or not this form of sensory suppression occurs. Participants performed simple reaching or exploratory movements. Tactile discrimination thresholds were calculated for vibratory stimuli delivered to participants' wrists while executing the movement, and while at rest (a tactile discrimination task, TD). We also measured discrimination performance in a same vs. different task for the explored materials during the execution of the different movements (a surface discrimination task, SD). The TD and SD tasks could either be performed singly or together, both under active movement and passive conditions. Consistent with previous results, tactile thresholds measured at rest were significantly lower than those measured during both active movement and passive touch (that is, tactile suppression was observed). Moreover, SD performance was significantly better under conditions of single-tasking, active movements, as well as exploratory movements, as compared to conditions of dual-tasking, passive movements, and reaching movements, respectively. Therefore, the present results demonstrate that when active hand movements are made with the purpose of gaining information about the surface properties of different materials an enhanced perceptual performance is observed. As such, it would appear that tactile suppression occurs for irrelevant tactual features during both reaching and exploratory movements, but not for those task-relevant features that result from action execution during tactile exploration. Taken together, then, these results support a context-dependent modulation of tactile suppression during movement execution.
Full Text Available Tactile perception is inhibited during movement execution, a phenomenon known as tactile suppression. Here, we investigated whether the type of movement determines whether or not this form of sensory suppression occurs. Participants performed simple reaching or exploratory movements. Tactile discrimination thresholds were calculated for vibratory stimuli delivered to participants’ wrists while executing the movement, and while at rest (a tactile discrimination task, TD. We also measured discrimination performance in a same vs. different task for the explored materials during the execution of the different movements (a surface discrimination task, SD. The TD and SD tasks could either be performed singly or together, both under active movement and passive conditions. Consistent with previous results, tactile thresholds measured at rest were significantly lower than those measured during both active movement and passive touch (that is, tactile suppression was observed. Moreover, SD performance was significantly better under conditions of single-tasking, active movements, as well as exploratory movements, as compared to conditions of dual-tasking, passive movements, and reaching movements, respectively. Therefore, the present results demonstrate that when active hand movements are made with the purpose of gaining information about the surface properties of different materials enhanced perceptual performance is observed. As such, it would appear that tactile suppression occurs for irrelevant tactual features during both reaching and exploratory movements, but not for those task-relevant features that result from action execution during tactile exploration. Taken together, then, these results support a context-dependent modulation of tactile suppression during movement execution.
Faugier, J; Sargeant, M
Studies on 'hidden populations', such as homeless people, prostitutes and drug addicts, raise a number of specific methodological questions usually absent from research involving known populations and less sensitive subjects. This paper examines the advantages and limitations of nonrandom methods of data collection such as snowball sampling. It reviews the currently available literature on sampling hard to reach populations and highlights the dearth of material currently available on this subject. The paper also assesses the potential for using these methods in nursing research. The sampling methodology used by Faugier (1996) in her study of prostitutes, HIV and drugs is used as a current example within this context.
Jason P. Gallivan
Full Text Available Mounting neural evidence suggests that, in situations in which there are multiple potential targets for action, the brain prepares, in parallel, competing movements associated with these targets, prior to implementing one of them. Central to this interpretation is the idea that competing viewed targets, prior to selection, are rapidly and automatically transformed into corresponding motor representations. Here, by applying target-specific, gradual visuomotor rotations and dissociating, unbeknownst to participants, the visual direction of potential targets from the direction of the movements required to reach the same targets, we provide direct evidence for this provocative idea. Our results offer strong empirical support for theories suggesting that competing action options are automatically represented in terms of the movements required to attain them. The rapid motor encoding of potential targets may support the fast optimization of motor costs under conditions of target uncertainty and allow the motor system to inform decisions about target selection.
Hyde, Christian; Wilson, Peter H.
In a recent study, children with movement clumsiness (or Developmental Coordination Disorder--DCD) were shown to have difficulties making rapid online corrections when reaching, demonstrated by slower and less accurate movements to double-step targets (Hyde & Wilson, 2011). These results suggest that children with DCD have difficulty using…
Full Text Available According to action-centered models of attention, the patterns of distractor interference that emerge in selective reaching tasks are related to the time and effort required to resolve a race for activation between competing target and non-target response producing processes. Previous studies have only used unimanual aiming tasks and, as such, only examined the effects of competition that occurs within a limb. The results of studies using unimanual aiming movements often reveal an "ipsilateral effect"--distractors on the same side of space as the effector cause greater interference than distractors on the opposite side of space. The cost of the competition when response selection is between the limbs has yet to be addressed. Participants in the present study executed reaching movements to 1 of 4 (2 left, 2 right possible target locations with and without a distractor. Participants made ipsilateral reaches (left hand to left targets, right hand to right targets. In contrast to studies using unimanual aiming movements, a "contralateral effect" was observed; distractors affording responses for the other hand (in contralateral space caused more interference than distractors affording responses for the same hand. The findings from the present research demonstrate that when certain portions of response planning must be resolved prior to response initiation, distractors that code for that dimension cause the greatest interference.
YANG Jingzhou(杨景周); ZHANG Yunqing(张云清); CHEN Liping(陈立平); ABDEL-MALEK Karim
Significant attention in recent years has been given to obtain a better understanding of human joint ranges, measurement, and functionality, especially in conjunction with commands issued by the central nervous system. While researchers have studied motor commands needed to drive a limb to follow a path trajectory, various computer algorithms have been reported that provide adequate analysis of limb modeling and motion. This paper uses a rigorous mathematical formulation to model human limbs, understand their reach envelope, delineate barriers therein where a trajectory becomes difficult to control, and help visualize these barriers. Workspaces of a typical forearm with 9 degrees of freedom, a typical finger modeled as a 4- degree-of-freedom system, and a lower extremity with 4 degrees of freedom are discussed. The results show that using the proposed formulation, joint limits play an important role in distinguishing the barriers.
Workers' education in the United States started as a pioneering movement at the turning of the centuries, developed all over the country in the 19203, and reached its height in of the 1930's. Women workers, college women, and activists of women's movements developed the workers education movement. With this development of Worker's education, women workers began to organize a labor movement for themselves. At first, women workers were a point force for Workers' education within the young labor...
Meli, Leonardo; Pacchierotti, Claudio; Prattichizzo, Domenico
This study presents a novel approach to force feedback in robot-assisted surgery. It consists of substituting haptic stimuli, composed of a kinesthetic component and a skin deformation, with cutaneous stimuli only. The force generated can then be thought as a subtraction between the complete haptic interaction, cutaneous, and kinesthetic, and the kinesthetic part of it. For this reason, we refer to this approach as sensory subtraction. Sensory subtraction aims at outperforming other nonkinesthetic feedback techniques in teleoperation (e.g., sensory substitution) while guaranteeing the stability and safety of the system. We tested the proposed approach in a challenging 7-DoF bimanual teleoperation task, similar to the Pegboard experiment of the da Vinci Skills Simulator. Sensory subtraction showed improved performance in terms of completion time, force exerted, and total displacement of the rings with respect to two popular sensory substitution techniques. Moreover, it guaranteed a stable interaction in the presence of a communication delay in the haptic loop.
Gabbard, Carl; Cordova, Alberto
In this article, the authors examined the effects of target information presented in different visual fields (lower, upper, central) on estimates of reach via use of motor imagery in children (5-11 years old) and young adults. Results indicated an advantage for estimating reach movements for targets placed in lower visual field (LoVF), with all…
Adam, Jos J.; Buetti, Simona; Kerzel, Dirk
Reaching to targets in space requires the coordination of eye and hand movements. In two experiments, we recorded eye and hand kinematics to examine the role of gaze position at target onset on eye-hand coordination and reaching performance. Experiment 1 showed that with eyes and hand aligned on the same peripheral start location, time lags…
@@ The new European REACH (Registration, Evaluation, Authorization of Chemicals) regulation has come into force. As soon as the REACH white paper was issued, Chinese enterprises started to research the possible impacts of REACH and prepare to cope with them. How then do these Chinese enterprises look at REACH? Following are views of some Chinese enterprises exporting chemical products to the European Union.
Elliott, Digby; Lyons, James; Hayes, Spencer J; Burkitt, James J; Roberts, James W; Grierson, Lawrence E M; Hansen, Steve; Bennett, Simon J
Recently our group forwarded a model of speed-accuracy relations in goal-directed reaching. A fundamental feature of our multiple process model was the distinction between two types of online regulation: impulse control and limb-target control. Impulse control begins during the initial stages of the movement trajectory and involves a comparison of actual limb velocity and direction to an internal representation of expectations about the limb trajectory. Limb-target control involves discrete error-reduction based on the relative positions of the limb and the target late in the movement. Our model also considers the role of eye movements, practice, energy optimization and strategic behavior in limb control. Here, we review recent work conducted to test specific aspects of our model. As well, we consider research not fully incorporated into our earlier contribution. We conclude that a slightly modified and expanded version of our model, that includes crosstalk between the two forms of online regulation, does an excellent job of explaining speed, accuracy, and energy optimization in goal-directed reaching.
Successful reaching requires postural control, either by active regulation or by postural support. The present paper reviews literature on typical and atypical development of reaching and postural control during infancy. Typically, reaching movements end in grasping around 4 months of age. Initially, reaches are characterized by large variation, including many trajectory corrections. During the first year, the movements get increasingly straight and smooth. Reaching in low-risk preterm infants is initially characterized by advanced development, but minor impairments may emerge in the second half of infancy. In high-risk preterm infants, development of reaching is characterized by delay and non-optimal reaching performance. Typical development of postural adjustments is characterized by variation and an increasing ability to adapt the variable repertoire to the specifics of the situation. The latter is facilitated by an increasing role of anticipatory mechanisms in the second half of infancy. Atypically developing infants may have a reduced repertoire and usually have difficulties in adapting postural adjustments. In infancy, most reaching movements are performed during sitting. The postural challenge of sitting may interfere in particular with the development of reaching in atypically developing infants. The practical implications of this suggestion are discussed.
Driver-Dunckley, Erika D; Adler, Charles H
This article summarizes what is currently known about sleep disturbances in several movement disorders including Parkinson disease, essential tremor, parkinsonism, dystonia, Huntington disease, myoclonus, and ataxias. There is an association between movement disorders and sleep. In some cases the prevalence of sleep disorders is much higher in patients with movement disorder, such as rapid eye movement sleep behavior disorder in Parkinson disease. In other cases, sleep difficulties worsen the involuntary movements. In many cases the medications used to treat patients with movement disorder disturb sleep or cause daytime sleepiness. The importance of discussing sleep issues in patients with movement disorders cannot be underestimated.
Jack Alexander De Havas
Full Text Available Involuntary movements share much of the motor control circuitry used for voluntary movement, yet the two can be easily distinguished. The Kohnstamm phenomenon (where a sustained, hard push produces subsequent involuntary arm raising is a useful experimental model for exploring differences between voluntary and involuntary movement. Both central and peripheral accounts have been proposed, but little is known regarding how the putative Kohnstamm generator responds to afferent input. We addressed this by obstructing the involuntary upward movement of the arm. Obstruction prevented the rising EMG pattern that characterizes the Kohnstamm. Importantly, once the obstruction was removed, the EMG signal resumed its former increase, suggesting a generator that persists despite peripheral input. When only one arm was obstructed during bilateral involuntary movements, only the EMG signal from the obstructed arm showed the effect. Upon release of the obstacle, the obstructed arm reached the same position and EMG level as the unobstructed arm. Comparison to matched voluntary movements revealed a preserved stretch response when a Kohnstamm movement first contacts an obstacle, and also an overestimation of the perceived contact force. Our findings support a hybrid central and peripheral account of the Kohnstamm phenomenon. The strange subjective experience of this involuntary movement is consistent with the view that movement awareness depends strongly on efference copies, but that the Kohnstamm generator does not produces efference copies.
Full Text Available Soft neurological signs (SNS are evident in the motor performance of children and disappear as the child grows up. Therefore SNS are used as criteria for evaluating age-appropriate development of neurological function. The aim of this study was to quantify SNS during arm movement in childhood. In this study, we focused on pronation and supination, which are arm movements included in the SNS examination. Two hundred and twenty-three typically developing children aged 4–12 years (107 boys, 116 girls and 18 adults aged 21–26 years (16 males, two females participated in the experiment. To quantify SNS during pronation and supination, we calculated several evaluation index scores: bimanual symmetry, compliance, postural stability, motor speed and mirror movement. These index scores were evaluated using data obtained from sensors attached to the participants’ hands and elbows. Each score increased as age increased. Results obtained using our system showed developmental changes that were consistent with criteria for SNS. We were able to successfully quantify SNS during pronation and supination. These results indicate that it may be possible to use our system as quantitative criteria for evaluating development of neurological function.
Cao, Jianwei; Khan, Bilal; Hervey, Nathan; Tian, Fenghua; Delgado, Mauricio R.; Clegg, Nancy J.; Smith, Linsley; Roberts, Heather; Tulchin-Francis, Kirsten; Shierk, Angela; Shagman, Laura; MacFarlane, Duncan; Liu, Hanli; Alexandrakis, George
Sensorimotor cortex plasticity induced by constraint-induced movement therapy (CIMT) in six children (10.2±2.1 years old) with hemiplegic cerebral palsy was assessed by functional near-infrared spectroscopy (fNIRS). The activation laterality index and time-to-peak/duration during a finger-tapping task and the resting-state functional connectivity were quantified before, immediately after, and 6 months after CIMT. These fNIRS-based metrics were used to help explain changes in clinical scores of manual performance obtained concurrently with imaging time points. Five age-matched healthy children (9.8±1.3 years old) were also imaged to provide comparative activation metrics for normal controls. Interestingly, the activation time-to-peak/duration for all sensorimotor centers displayed significant normalization immediately after CIMT that persisted 6 months later. In contrast to this improved localized activation response, the laterality index and resting-state connectivity metrics that depended on communication between sensorimotor centers improved immediately after CIMT, but relapsed 6 months later. In addition, for the subjects measured in this work, there was either a trade-off between improving unimanual versus bimanual performance when sensorimotor activation patterns normalized after CIMT, or an improvement occurred in both unimanual and bimanual performance but at the cost of very abnormal plastic changes in sensorimotor activity.
Nowlan, N C
Foetal movements commence at seven weeks of gestation, with the foetal movement repertoire including twitches, whole body movements, stretches, isolated limb movements, breathing movements, head and neck movements, jaw movements (including yawning, sucking and swallowing) and hiccups by ten weeks of gestational age. There are two key biomechanical aspects to gross foetal movements; the first being that the foetus moves in a dynamically changing constrained physical environment in which the freedom to move becomes increasingly restricted with increasing foetal size and decreasing amniotic fluid. Therefore, the mechanical environment experienced by the foetus affects its ability to move freely. Secondly, the mechanical forces induced by foetal movements are crucial for normal skeletal development, as evidenced by a number of conditions and syndromes for which reduced or abnormal foetal movements are implicated, such as developmental dysplasia of the hip, arthrogryposis and foetal akinesia deformation sequence. This review examines both the biomechanical effects of the physical environment on foetal movements through discussion of intrauterine factors, such as space, foetal positioning and volume of amniotic fluid, and the biomechanical role of gross foetal movements in human skeletal development through investigation of the effects of abnormal movement on the bones and joints. This review also highlights computational simulations of foetal movements that attempt to determine the mechanical forces acting on the foetus as it moves. Finally, avenues for future research into foetal movement biomechanics are highlighted, which have potential impact for a diverse range of fields including foetal medicine, musculoskeletal disorders and tissue engineering.
Full Text Available Foetal movements commence at seven weeks of gestation, with the foetal movement repertoire including twitches, whole body movements, stretches, isolated limb movements, breathing movements, head and neck movements, jaw movements (including yawning, sucking and swallowing and hiccups by ten weeks of gestational age. There are two key biomechanical aspects to gross foetal movements; the first being that the foetus moves in a dynamically changing constrained physical environment in which the freedom to move becomes increasingly restricted with increasing foetal size and decreasing amniotic fluid. Therefore, the mechanical environment experienced by the foetus affects its ability to move freely. Secondly, the mechanical forces induced by foetal movements are crucial for normal skeletal development, as evidenced by a number of conditions and syndromes for which reduced or abnormal foetal movements are implicated, such as developmental dysplasia of the hip, arthrogryposis and foetal akinesia deformation sequence. This review examines both the biomechanical effects of the physical environment on foetal movements through discussion of intrauterine factors, such as space, foetal positioning and volume of amniotic fluid, and the biomechanical role of gross foetal movements in human skeletal development through investigation of the effects of abnormal movement on the bones and joints. This review also highlights computational simulations of foetal movements that attempt to determine the mechanical forces acting on the foetus as it moves. Finally, avenues for future research into foetal movement biomechanics are highlighted, which have potential impact for a diverse range of fields including foetal medicine, musculoskeletal disorders and tissue engineering.
of the Array Operations Site. This means surviving strong winds and temperatures between +20 and -20 Celsius whilst being able to point precisely enough that they could pick out a golf ball at a distance of 15 km, and to keep their smooth reflecting surfaces accurate to better than 25 micrometres (less than the typical thickness of a human hair). Once the transporter reached the high plateau it carried the antenna to a concrete pad - a docking station with connections for power and fibre optics - and positioned it with an accuracy of a few millimetres. The transporter is guided by a laser steering system and, just like some cars today, also has ultrasonic collision detectors. These sensors ensure the safety of the state-of-the-art antennas as the transporter drives them across what will soon be a rather crowded plateau. Ultimately, ALMA will have at least 66 antennas distributed over about 200 pads, spread over distances of up to 18.5 km and operating as a single, giant telescope. Even when ALMA is fully operational, the transporters will be used to move the antennas between pads to reconfigure the telescope for different kinds of observations. "Transporting our first antenna to the Chajnantor plateau is a epic feat which exemplifies the exciting times in which ALMA is living. Day after day, our global collaboration brings us closer to the birth of the most ambitious ground-based astronomical observatory in the world", said Thijs de Graauw, ALMA Director. This first ALMA antenna at the high site will soon be joined by others and the ALMA team looks forward to making their first observations from the Chajnantor plateau. They plan to link three antennas by early 2010, and to make the first scientific observations with ALMA in the second half of 2011. ALMA will help astronomers answer important questions about our cosmic origins. The telescope will observe the Universe using light with millimetre and submillimetre wavelengths, between infrared light and radio waves in
Naranjo, J R; Brovelli, A; Longo, R; Budai, R; Kristeva, R; Battaglini, P P
Visuomotor transformation processes are essential when accurate reaching movements towards a visual target have to be performed. In contrast, those transformations are not needed for similar, but non-visually guided, arm movements. According to previous studies, these transformations are carried out by neuronal populations located in the parietal and frontal cortical areas (the so-called "dorsal visual stream"). However, it is still debated whether these processes are mediated by the sequential and/or parallel activation of the frontoparietal areas. To investigate this issue, we designed a task where the same visual cue could represent either the target of a reaching/pointing movement or the go-signal for a similar but non-targeting arm movement. By subtracting the event-related potentials (ERPs) recorded from healthy subjects performing the two conditions, we identified the brain processes underlying the visuomotor transformations needed for accurate reaching/pointing movements. We then localized the generators by means of cortical current density (CCD) reconstruction and studied their dynamics from visual cue presentation to movement onset. The results showed simultaneous activation of the parietal and frontal areas from 140 to 260 ms. The results are interpreted as neural correlates of two critical phases of visuomotor integration, namely target selection and movement selection. Our findings suggest that the visuomotor transformation processes required for correct reaching/pointing movements do not rely on a purely sequential activation of the frontoparietal areas, but mainly on a parallel information processing system, where feedback circuits play an important role before movement onset.
California Department of Resources — The Stream Habitat - NCWAP - Reach Summary [ds158] shapefile contains in-stream habitat survey data summarized to the stream reach level. It is a derivative of the...
Riisgaard Hansen, Thomas; Eriksson, Eva; Lykke-Olesen, Andreas
In this paper we explore the space in which movement based interaction takes place. We have in several projects explored how fixed and mobile cameras can be used in movement based interaction and will shortly describe these projects. Based on our experience with working with movement-based intera......In this paper we explore the space in which movement based interaction takes place. We have in several projects explored how fixed and mobile cameras can be used in movement based interaction and will shortly describe these projects. Based on our experience with working with movement...
Cochet, Hélène; Centelles, Laurie; Jover, Marianne; Plachta, Suzy; Vauclair, Jacques
Manual asymmetries emerge very early in development and several researchers have reported a significant right-hand bias in toddlers although this bias fluctuates depending on the nature of the activity being performed. However, little is known about the further development of asymmetries in preschoolers. In this study, patterns of hand preference were assessed in 50 children aged 3-5 years for different activities, including reaching movements, pointing gestures and symbolic gestures. Contrary to what has been reported in children before 3 years of age, we did not observe any difference in the mean handedness indices obtained in each task. Moreover, the asymmetry of reaching was found to correlate with that of pointing gestures, but not with that of symbolic gestures. In relation to the results reported in infants and adults, this study may help deciphering the mechanisms controlling the development of handedness by providing measures of manual asymmetries in an age range that has been so far rather neglected.
Buchanan, John J; Dean, Noah
The experiment undertaken was designed to elucidate the impact of model skill level on observational learning processes. The task was bimanual circle tracing with a 90° relative phase lead of one hand over the other hand. Observer groups watched videos of either an instruction model, a discovery model, or a skilled model. The instruction and skilled model always performed the task with the same movement strategy, the right-arm traced clockwise and the left-arm counterclockwise around circle templates with the right-arm leading. The discovery model used several movement strategies (tracing-direction/hand-lead) during practice. Observation of the instruction and skilled model provided a significant benefit compared to the discovery model when performing the 90° relative phase pattern in a post-observation test. The observers of the discovery model had significant room for improvement and benefited from post-observation practice of the 90° pattern. The benefit of a model is found in the consistency with which that model uses the same movement strategy, and not within the skill level of the model. It is the consistency in strategy modeled that allows observers to develop an abstract perceptual representation of the task that can be implemented into a coordinated action. Theoretically, the results show that movement strategy information (relative motion direction, hand lead) and relative phase information can be detected through visual perception processes and be successfully mapped to outgoing motor commands within an observational learning context.
Goldfield, Eugene C.
Investigated postural constraints on movement of 15 6-month-old infants. Results suggested that each of the developing capabilities of orienting, reaching, and kicking assumed a specific function for locomotion at the stage of crawling. (RJC)
... work properly. There are many kinds of eye movement disorders. Two common ones are Strabismus - a disorder in ... the eyes, sometimes called "dancing eyes" Some eye movement disorders are present at birth. Others develop over time ...
Presents an activity that employs movement to enable students to understand concepts related to plate tectonics. Argues that movement brings topics to life in a concrete way and helps children retain knowledge. (DDR)
Mirror writing is a phenomenon which can be deliberate, spontaneous, or involuntary. It has been anecdotally reported that mirror writing is easiest when simultaneously writing forwards with the dominant hand. A study carried out by McIntosh and Della Sala on a mirror writing artist named KB, found that their results concurred with this, and that mirror motor movements were being used when KB mirror writes with the left hand while simultaneously writing forwards with the right, in a motor con...
de Haan, A M; Van der Stigchel, S; Nijnens, C M; Dijkerman, H C
When reaching for target objects, we hardly ever collide with other objects located in our working environment. Behavioural studies have demonstrated that the introduction of non-target objects into the workspace alters both spatial and temporal parameters of reaching trajectories. Previous studies have shown the influence of spatial object features (e.g. size and position) on obstacle avoidance movements. However, obstacle identity may also play a role in the preparation of avoidance responses as this allows prediction of possible negative consequences of collision based on recognition of the obstacle. In this study we test this hypothesis by asking participants to reach towards a target as quickly as possible, in the presence of an empty or full glass of water placed about half way between the target and the starting position, at 8 cm either left or right of the virtual midline. While the spatial features of full and empty glasses of water are the same, the consequences of collision are clearly different. Indeed, when there was a high chance of collision, reaching trajectories veered away more from filled than from empty glasses. This shows that the identity of potential obstacles, which allows for estimating the predicted consequences of collision, is taken into account during obstacle avoidance.
Full Text Available We examined an eye-hand coordination task where optimal visual search and hand movement strategies were inter-related. Observers were asked to find and touch a target among five distractors on a touch screen. Their reward for touching the target was reduced by an amount proportional to how long they took to locate and reach to it. Coordinating the eye and the hand appropriately would markedly reduce the search-reach time. Using statistical decision theory we derived the sequence of interrelated eye and hand movements that would maximize expected gain and we predicted how hand movements should change as the eye gathered further information about target location. We recorded human observers' eye movements and hand movements and compared them with the optimal strategy that would have maximized expected gain. We found that most observers failed to adopt the optimal search-reach strategy. We analyze and describe the strategies they did adopt.
Full Text Available New movement assessment and data analysis methods are developed to quantify human arm motion patterns during physical interaction with robotic devices for rehabilitation. These methods provide metrics for future use in diagnosis, assessment and rehabilitation of subjects with affected arm movements. Specifically, the current study uses existing pattern recognition methods to evaluate the effect of age on performance of a specific motion, reaching to a target by moving the end-effector of a robot (an X-Y table. Differences in the arm motion patterns of younger and older subjects are evaluated using two measures: the principal component analysis similarity factor (SPCA to compare path shape and the number of Fourier modes representing 98% of the path ‘energy’ to compare the smoothness of movement, a particularly important variable for assessment of pathologic movement. Both measures are less sensitive to noise than others previously reported in the literature and preserve information that is often lost through other analysis techniques. Data from the SPCA analysis indicate that age is a significant factor affecting the shapes of target reaching paths, followed by reaching movement type (crossing body midline/not crossing and reaching side (left/right; hand dominance and trial repetition are not significant factors. Data from the Fourier-based analysis likewise indicate that age is a significant factor affecting smoothness of movement, and movements become smoother with increasing trial number in both younger and older subjects, although more rapidly so in younger subjects. These results using the proposed data analysis methods confirm current practice that age-matched subjects should be used for comparison to quantify recovery of arm movement during rehabilitation. The results also highlight the advantages that these methods offer relative to other reported measures.
There are many links between literacy and movement. Movement and language are both forms of communication and self-expression. Rhythm is an essential component of both language and movement. While people may think of rhythm primarily in musical terms, there is a rhythm to words and sentences as well. Individuals develop an internal rhythm when…
The movements of such higher predicates as time, locative, and complementation verbs are studied, and Tai's Predicate Placement Constraint is rejected as an incorrect account of predicate movements in Chinese. It is proposed, on the other hand, that there is only leftward movement involving predicates in Chinese. (Author)
The article examines the role of social movements in the development of scientific knowledge. Interactions between social movements and science in broad, historical terms are discussed. The relations between the new social movements of the 1960s and 1970s and changes in the contemporary scientific...
Jenni M Karl
Full Text Available The Dual Visuomotor Channel Theory proposes that manual prehension consists of two temporally integrated movements, each subserved by distinct visuomotor pathways in occipitoparietofrontal cortex. The Reach is mediated by a dorsomedial pathway and transports the hand in relation to the target’s extrinsic properties (i.e., location and orientation. The Grasp is mediated by a dorsolateral pathway and opens, preshapes, and closes the hand in relation to the target’s intrinsic properties (i.e., size and shape. Here, neuropsychological, developmental, and comparative evidence is reviewed to show that the Reach and the Grasp have different evolutionary origins. First, the removal or degradation of vision causes prehension to decompose into its constituent Reach and Grasp components, which are then executed in sequence or isolation. Similar decomposition occurs in optic ataxic patients following cortical injury to the Reach and Grasp pathways and after corticospinal tract lesions in non-human primates. Second, early nonvisual PreReach and PreGrasp movements develop into mature Reach and Grasp movements but are only integrated under visual control after a prolonged developmental period. Third, comparative studies reveal many similarities between stepping movements and the Reach and between food handling movements and the Grasp, suggesting that the Reach and Grasp are derived from different evolutionary antecedents. The evidence is discussed in relation to the ideas that dual visuomotor channels in primate parietofrontal cortex emerged as a result of distinct evolutionary origins for the Reach and Grasp; that foveated vision in primates serves to integrate the Reach and Grasp into a single prehensile act; and, that flexible recombination of discrete Reach and Grasp movements under various forms of sensory and cognitive control can produce adaptive behavior.
Blais, Mélody; Martin, Elodie; Albaret, Jean-Michel; Tallet, Jessica
Despite the apparent age-related decline in perceptual-motor performance, recent studies suggest that the elderly people can improve their reaction time when relevant sensory information are available. However, little is known about which sensory information may improve motor behaviour itself. Using a synchronization task, the present study investigates how visual and/or auditory stimulations could increase accuracy and stability of three bimanual coordination modes produced by elderly and young adults. Neurophysiological activations are recorded with ElectroEncephaloGraphy (EEG) to explore neural mechanisms underlying behavioural effects. Results reveal that the elderly stabilize all coordination modes when auditory or audio-visual stimulations are available, compared to visual stimulation alone. This suggests that auditory stimulations are sufficient to improve temporal stability of rhythmic coordination, even more in the elderly. This behavioural effect is primarily associated with increased attentional and sensorimotor-related neural activations in the elderly but similar perceptual-related activations in elderly and young adults. This suggests that, despite a degradation of attentional and sensorimotor neural processes, perceptual integration of auditory stimulations is preserved in the elderly. These results suggest that perceptual-related brain plasticity is, at least partially, conserved in normal aging.
Puttemans, Veerle; Wenderoth, Nicole; Swinnen, Stephan P
Little is known about activation changes reflecting overlearning, i.e., extensive motor training beyond asymptotic performance. Here we used functional magnetic resonance imaging to trace the neural shifts from an initial to a skilled (learning) and finally overlearned stage (automatization). Scanning occurred before training (PRE) and after 1 (MID) and 2 weeks (POST) of intensive practice on a new bimanual coordination task (>10,500 cycles). Kinematics revealed major improvements between PRE and MID sessions, whereas MID to POST session performance leveled off, indicative of learning and automatization, respectively. Imaging findings showed that activation decreased in bilateral opercular areas, bilateral ventrolateral prefrontal cortex, the right ventral premotor and supramarginal gyrus, and the anterior cingulate sulcus during the learning stage and in the supplementary motor area during the automatization stage. These changes are hypothesized to reflect decreases in attention-demanding sensory processing, as well as suppression of preferred coordination tendencies as a prelude to acquiring new coordination modes. Conversely, learning-related increases were observed in the primary motor cortex (M1), posterior cingulate zone (PCZ), putamen, and right anterior cerebellum. Importantly, both M1 and PCZ activation decreased again to initial level (PRE) during automated performance (POST). Only the putamen and anterior cerebellum remained more activated across both learning and automatization stages, supporting their crucial role in long-term motor memory formation for coordination tasks.
Coxon, James P; Goble, Daniel J; Van Impe, Annouchka; De Vos, Jeroen; Wenderoth, Nicole; Swinnen, Stephan P
Structural and neurochemical changes in frontostriatal circuits are thought to underlie age-related behavioral deficits on cognitive tasks. Here, we test the hypothesis that age-related motor switching deficits are associated with reduced basal ganglia (BG) function. Right-handed volunteers (15 Old, and 15 Young) made spatially and temporally coupled bimanual circular motions during event-related FMRI. A visual cue signaled the right hand to Switch or Continue its circling direction. Switching from mirror symmetric to asymmetric (SW»ASYMM) took longer and resulted in more contralateral (left-) hand disruptions than vice versa. These effects were more pronounced in the elderly, showing that the ability to suppress and flexibly adapt motor behavior (agility) declines with age. For both groups, switching activated the BG and a typical network for task-set implementation, including dorsal anterior cingulate cortex/supplementary motor area (pre-SMA, SMA-proper) and anterior insula/inferior frontal gyrus. A region of interest analysis revealed significantly reduced SW»ASYMM activation in bilateral subthalamic nucleus and right globus pallidus, only in the elderly. Age-related behavioral deficits may be related to inefficient recruitment of cortico-BG loops to suppress undesired movements. The elderly may use an alternative strategy to select the required movement pattern as indicated by increased activation of prefrontal cortex.
Full Text Available The detection of movement-related components of the brain activity is useful in the design of brain machine interfaces. A common approach is to classify the brain activity into a number of templates or states. To find these templates, the neural responses are averaged over each movement task. For averaging to be effective, one must assume that the neural components occur at identical times over repeated trials. However, complex arm movements such as reaching and grasping are prone to cross-trial variability due to the way movements are performed. Typically initiation time, duration of movement and movement speed are variable even as a subject tries to reproduce the same task identically across trials. Therefore, movement-related neural activity will tend to occur at different times across each trial. Due to this mismatch, the averaging of neural activity will not bring into salience movement-related components. To address this problem, we present a method of alignment that accounts for the variabilities in the way the movements are conducted. In this study, arm speed was used to align neural activity. Four subjects had electrocorticographic (ECoG electrodes implanted over their primary motor cortex and were asked to perform reaching and retrieving tasks using the upper limb contralateral to the site of electrode implantation. The arm speeds were aligned using a nonlinear transformation of the temporal axes resulting in averaged spectrograms with superior visualization of movement-related neural activity when compared to averaging without alignment.
Review of: Quantitative Analysis of Movement: Measuring and Modeling Population Redistribution in Animals and Plants. Peter Turchin. 1998. Sinauer Associates, Sunderland, MA. 306 pages. $38.95 (paper).
Astrid Franziska Junghans
Full Text Available Objects, such as food, in the environment automatically activate and facilitate affordances, the possibilities for motoric movements in interaction with the objects. Previous research has shown that affordance activation is contingent upon the distance of the object with only proximal objects activating potential movements. However, the effect of affordance-activating proximal objects on the ability to inhibit movements has been unaddressed.The current study addressed this question with two experiments on long-tailed macaques. In both experiments monkeys were situated behind a Plexiglass screen that prevented direct access to food placed right behind the screen. The food could only be reached via a detour through one of two holes on the sides of the screen. It was assessed whether monkeys’ ability to inhibit the unsuccessful immediate reaching movement forward toward the food depended on the distance at which the food was presented. Results of both Experiments revealed that monkeys reached for the proximally positioned food significantly more than for the distally positioned food, despite this Plexiglass screen preventing successful obtainment of the food. The findings reveal the effect of proximal, affordance-activating objects on the ability to resist movements involved in interacting with the objects. Implications for humans, living in environments in which proximal, or accessible food is constantly available are discussed. The findings can contribute to an understanding of why resisting accessible food in the environment is often unsuccessful.
de Graaf-Peters, Victorine B.; Bakker, Hanneke; van Eykern, Leo A.; Otten, Bert; Hadders-Algra, Mijna
Adequate postural control is a prerequisite for daily activities such as reaching for an object. However, knowledge on the relationship between postural adjustments and the quality of reaching movements during human ontogeny is scarce. Therefore we evaluated the development of the relationship betwe
Renata C. M. Lima
Full Text Available Objective: To investigate the influence of hand dominance on the maintenance of gains after home-based modified constraint-induced movement therapy (mCIMT. Method: Aprevious randomized controlled trial was conducted to examine the addition of trunk restraint to the mCIMT. Twenty-two chronic stroke survivors with mild to moderate motor impairments received individual home-based mCIMT with or without trunk restraints, five times per week, three hours daily over two weeks. In this study, the participants were separated into dominant group, which had their paretic upper limb as dominant before the stroke (n=8, and non-dominant group (n=14 for analyses. The ability to perform unimanual tasks was measured by the Wolf Motor Function Test (WMFT and the Motor Activity Log (MAL, whereas the capacity to perform bimanual tasks was measured using the Bilateral Activity Assessment Scale (BAAS. Results: Analysis revealed significant positive effects on the MAL amount of use and quality of the movement scales, as well as on the BAAS scores after intervention, with no differences between groups. Both groups maintained the bimanual improvements during follow-ups (BAAS-seconds 0.1, 95% CI -10.0 to 10.0, however only the dominant group maintained the unilateral improvements (MAL-amount of use: 1.5, 95% CI 0.7 to 2.3; MAL-quality: 1.3, 95% CI 0.5 to 2.1. Conclusions: Upper limb dominance did not interfere with the acquisition of upper limb skills after mCIMT. However, the participants whose paretic upper limb was dominant demonstrated better abilities to maintain the unilateral gains. The bilateral improvements were maintained, regardless of upper limb dominance.
Full Text Available Tactile perception is inhibited during goal-directed reaching movements (sensory suppression. Here, participants performed simple reaching or exploratory movements (where contact with the table surface was maintained. We measured tactile discrimination thresholds for vibratory stimuli delivered to participants' wrists while executing the movement, and while at rest. Moreover, we measured discrimination performance (in a same vs. different task for the materials covering the table surface, during the execution of the different movements. The threshold and discrimination tasks could be performed either singly or together, both under active movement and passive conditions (ie, no movement required, but with tactile stimulation. Thresholds measured at rest were significantly lower than thresholds measured during both active movements and passive touches. This provides a clear indication of sensory suppression during movement execution. Moreover, the discrimination data revealed main effects of task (single vs. dual, movement execution type (passive vs. active, and movement type (reach vs. exploration: Discrimination performance was significantly higher under conditions of single-tasking, active movements, as well as exploratory movements. Therefore, active movement of the hand with the purpose of gaining tactual information about the surface of the table gives rise to enhanced performance, thus suggesting that we feel more when we need to; It would appear that tactual information is prioritized when relevant for the movement being executed.
Jackson, Stephen R.; Newport, Roger; Husain, Masud; Fowlie, Jane E.; O'Donoghue, Michael; Bajaj, Nin
Optic ataxia (OA) is generally thought of as a disorder of visually guided reaching movements that cannot be explained by any simple deficit in visual or motor processing. In this paper we offer a new perspective on optic ataxia; we argue that the popular characterisation of this disorder is misleading and is unrepresentative of the pattern of…
Full Text Available The paper presents a robotics-based model for choice reaching experiments on visual attention. In these experiments participants were asked to make rapid reach movements towards a target in an odd-colour search task, i.e. reaching for a green square among red squares and vice versa (e.g. Song & Nakayama, 2008. Interestingly these studies found that in a high number of trials movements were initially directed towards a distractor and only later were adjusted towards the target. These curved trajectories occurred particularly frequently when the target in the directly preceding trial had a different colour (priming effect. Our model is embedded in a closed-loop control of a LEGO robot arm aiming to mimic these reach movements. The model is based on our earlier work which suggests that target selection in visual search is implemented through parallel interactions between competitive and cooperative processes in the brain (Heinke & Backhaus, 2011; Heinke & Humphreys, 2003. To link this model with the control of the robot arm we implemented a topological representation of movement parameters following the dynamic field theory (Erlhagen & Schoener, 2002. The robot arm is able to mimic the results of the odd-colour search task including the priming effect and also generates human-like trajectories with a bell-shaped velocity profile. Theoretical implications and predictions are discussed in the paper.
Van Der Fits, IBM; Hadders-Algra, M
Reaching movements in adults are accompanied by complex postural adjustments which are controlled by spatial, temporal, and quantitative parameters. The basic postural adjustments are selected on the basis of the spatial parameter, whereas fine tuning of the pattern is guided by temporal and quantit
US Fish and Wildlife Service, Department of the Interior — Increase the diversity of the seed mix on approximately 250 acres in the Ringold Unit of the Hanford Reach National Monument (Monument) treated with aminopyralid as...
Esslinger, Keri; Esslinger, Travis; Bagshaw, Jarad
This article describes the use of live action role-playing, or "LARPing," as a non-traditional activity that has the potential to reach students who are not interested in traditional physical education.
Scientist of the U.S. Department of Energy in Fermilab and collaborators of the US/CMS project announced that the world's largest superconducting solenoid magnet has reached full field in tests at CERN. (1 apge)
... page: https://medlineplus.gov/news/fullstory_161640.html Women Reaching Equality in Dubious Habit: Drinking Females also ... 25, 2016 MONDAY, Oct. 24, 2016 (HealthDay News) -- Women have made major strides towards equality with men, ...
James L Patton
Full Text Available We studied reach adaptation to a 30° visuomotor rotation to determine whether augmented error feedback can promote faster and more complete motor learning. Four groups of healthy adults reached with their unseen arm to visual targets surrounding a central starting point. A manipulandum tracked hand motion and projected a cursor onto a display immediately above the horizontal plane of movement. For one group, deviations from the ideal movement were amplified with a gain of 2 whereas another group experienced a gain of 3.1. The third group experienced an offset equal to the average error seen in the initial perturbations, while a fourth group served as controls. Learning in the gain 2 and offset groups was nearly twice as fast as controls. Moreover, the offset group averaged more reduction in error. Such error augmentation techniques may be useful for training novel visuomotor transformations as required of robotic teleoperators or in movement rehabilitation of the neurologically impaired.
Patton, James L; Wei, Yejun John; Bajaj, Preeti; Scheidt, Robert A
We studied reach adaptation to a 30° visuomotor rotation to determine whether augmented error feedback can promote faster and more complete motor learning. Four groups of healthy adults reached with their unseen arm to visual targets surrounding a central starting point. A manipulandum tracked hand motion and projected a cursor onto a display immediately above the horizontal plane of movement. For one group, deviations from the ideal movement were amplified with a gain of 2 whereas another group experienced a gain of 3.1. The third group experienced an offset equal to the average error seen in the initial perturbations, while a fourth group served as controls. Learning in the gain 2 and offset groups was nearly twice as fast as controls. Moreover, the offset group averaged more reduction in error. Such error augmentation techniques may be useful for training novel visuomotor transformations as required of robotic teleoperators or in movement rehabilitation of the neurologically impaired.
Fenichel, Emily, Ed.
This newsletter theme issue focuses on dance, play, and movement therapy for infants and toddlers with disabilities. Individual articles are: "Join My Dance: The Unique Movement Style of Each Infant and Toddler Can Invite Communication, Expression and Intervention" (Suzi Tortora); "Dynamic Play Therapy: An Integrated Expressive Arts Approach to…
The main objective of this thesis is to develop an approach for exploring, analysing and interpreting movement patterns of pedestrians interacting with the environment. This objective is broken down in sub-objectives related to four research questions. A case study of the movement of visitors in a n
Hashiguchi, S.; Khadijah, Siti; Kuwajima, T.; Ohki, M.; Tacano, M.; Sikula, J.
Movements of amoebas were automatically traced using the difference between two successive frames of the microscopic movie. It was observed that the movements were almost random in that the directions and the magnitudes of the successive two steps are not correlated, and that the distance from the origin was proportional to the square root of the step number.
Hyde, Christian; Fuelscher, Ian; Enticott, Peter G; Reid, Susan M; Williams, Jacqueline
This study aimed to investigate the integrity of on-line control of reaching in congenital spastic hemiplegia in light of disparate evidence. Twelve children with and without spastic hemiplegia (11-17 years old) completed a double-step reaching task requiring them to reach and touch a target that remained stationary for most trials (viz nonjump trial) but unexpectedly displaced laterally at movement onset for a minority of trials (20%: known as jump trials). Although children with spastic hemiplegia were generally slower than age-matched controls, they could account for target perturbation at age-appropriate levels shown by a lack of interaction effect on movement time and nonsignificant group difference for time to reach trajectory correction on jump trials. Our data suggest that at a group level, on-line control of reaching may be age-appropriate in spastic hemiplegia. However, our data also highlight the need to experimentally acknowledge the considerable heterogeneity of the spastic hemiplegia population when investigating motor cognition.
Harbourne, Regina T; Lobo, Michele A; Karst, Gregory M; Galloway, James Cole
The development of reaching and of sitting during the first year of life is typically studied as separate yet related behaviors. Interestingly, very soon after learning to reach, 4-7-month-old infants start coordinating their arms with their trunk and legs for sitting. In this longitudinal study, we focused, for the first time, on how infants learn to use their arms for the dual tasks of reaching for objects while providing arm support as they learn to sit. We hypothesized that the use of arms for support during sitting development would be a temporary perturbation to reaching and result in a nonlinear progression of reaching skill. Eleven infants were studied monthly from the time they began to prop sit to the time of sitting independence (5-8 months of age). Behavioral coding, kinematics, and electromyography (EMG) characterized reaching and posture while infants sat as independently as possible. Results revealed significant changes across time in trunk movement and hand use as infants transitioned through three stages of sitting: with arm support, sitting briefly without arm support, and sitting independently. Infants used their hands more for contacting objects and less for posture support linearly across time. In contrast, changes in posture control as indicated by pelvis and trunk movement demonstrated a U-shaped curve with more movement of these two body segments during the middle stage of sitting than in the first or last stage. During the middle stage of sitting infants reached persistently even though posture control, measured by pelvis and trunk movement, appeared to be significantly challenged. Muscle activation consisted of tonic and variable combinations of muscle pairings in early sitting. As infants progressed to sitting without hand support, variable but successful strategies utilizing lower extremity muscles in a tight linkage with reach onset emerged to provide prospective control for reaching. Our findings support the contention that reaching
Harris, Christopher M
How should robotic or prosthetic arms be programmed to move? Copying human smooth movements is popular in synthetic systems, but what does this really achieve? We cannot address these biomimetic issues without a deep understanding of why natural movements are so stereotyped. In this article, we distinguish between 'functional' and 'aesthetic' biomimetics. Functional biomimetics requires insight into the problem that nature has solved and recognition that a similar problem exists in the synthetic system. In aesthetic biomimetics, nature is copied for its own sake and no insight is needed. We examine the popular minimum jerk (MJ) model that has often been used to generate smooth human-like point-to-point movements in synthetic arms. The MJ model was originally justified as maximizing 'smoothness'; however, it is also the limiting optimal trajectory for a wide range of cost functions for brief movements, including the minimum variance (MV) model, where smoothness is a by-product of optimizing the speed-accuracy trade-off imposed by proportional noise (PN: signal-dependent noise with the standard deviation proportional to mean). PN is unlikely to be dominant in synthetic systems, and the control objectives of natural movements (speed and accuracy) would not be optimized in synthetic systems by human-like movements. Thus, employing MJ or MV controllers in robotic arms is just aesthetic biomimetics. For prosthetic arms, the goal is aesthetic by definition, but it is still crucial to recognize that MV trajectories and PN are deeply embedded in the human motor system. Thus, PN arises at the neural level, as a recruitment strategy of motor units and probably optimizes motor neuron noise. Human reaching is under continuous adaptive control. For prosthetic devices that do not have this natural architecture, natural plasticity would drive the system towards unnatural movements. We propose that a truly neuromorphic system with parallel force generators (muscle fibres) and noisy
Eckstein, Aleksandra; Krzeszowiec, Weronika; Waligórski, Piotr; Gabryś, Halina
Auxin is involved in a wide spectrum of physiological processes in plants, including responses controlled by the blue light photoreceptors phototropins: phototropic bending and stomatal movement. However, the role of auxin in phototropin-mediated chloroplast movements has never been studied. To address this question we searched for potential interactions between auxin and the chloroplast movement signaling pathway using different experimental approaches and two model plants, Arabidopsis thaliana and Nicotiana tabacum. We observed that the disturbance of auxin homeostasis by shoot decapitation caused a decrease in chloroplast movement parameters, which could be rescued by exogenous auxin application. In several cases, the impairment of polar auxin transport, by chemical inhibitors or in auxin carrier mutants, had a similar negative effect on chloroplast movements. This inhibition was not correlated with changes in auxin levels. Chloroplast relocations were also affected by the antiauxin p-chlorophenoxyisobutyric acid and mutations in genes encoding some of the elements of the SCF(TIR1)-Aux/IAA auxin receptor complex. The observed changes in chloroplast movement parameters are not prominent, which points to a modulatory role of auxin in this process. Taken together, the obtained results suggest that auxin acts indirectly to regulate chloroplast movements, presumably by regulating gene expression via the SCF(TIR1)-Aux/IAA-ARF pathway. Auxin does not seem to be involved in controlling the expression of phototropins.
Full Text Available To investigate changes of muscle recruitment and coordination following constraint-induced movement therapy, constraint-induced movement therapy plus electrical stimulation, and traditional occupational therapy in treating hand dysfunction.In a randomized, single-blind, controlled trial, children with hemiplegic cerebral palsy were randomly assigned to receive constraint-induced movement therapy (n = 22, constraint-induced movement therapy plus electrical stimulation (n = 23, or traditional occupational therapy (n = 23. Three groups received a 2-week hospital-based intervention and a 6-month home-based exercise program following hospital-based intervention. Constraint-induced movement therapy involved intensive functional training of the involved hand during which the uninvolved hand was constrained. Electrical stimulation was applied on wrist extensors of the involved hand. Traditional occupational therapy involved functional unimanual and bimanual training. All children underwent clinical assessments and surface electromyography (EMG at baseline, 2 weeks, 3 and 6 months after treatment. Surface myoelectric signals were integrated EMG, root mean square and cocontraction ratio. Clinical measures were grip strength and upper extremity functional test.Constraint-induced movement therapy plus electrical stimulation group showed both a greater rate of improvement in integrated EMG of the involved wrist extensors and cocontraction ratio compared to the other two groups at 3 and 6 months, as well as improving in root mean square of the involved wrist extensors than traditional occupational therapy group (p<0.05. Positive correlations were found between both upper extremity functional test scores and integrated EMG of the involved wrist as well as grip strength and integrated EMG of the involved wrist extensors (p<0.05.Constraint-induced movement therapy plus electrical stimulation is likely to produce the best outcome in improving muscle recruitment
Nabe-Nielsen, Kirsten; Jørgensen, Marie Birk; Garde, Anne Helene
to some extent explained the lack of reach of interventions especially among fixed evening workers. CONCLUSIONS: In the light of the evidence of shift workers' stressful working conditions, we suggest that future studies focus on the generalizability of results of the present study and on how to reach......PURPOSE: Shift workers are exposed to more physical and psychosocial stressors in the working environment as compared to day workers. Despite the need for targeted prevention, it is likely that workplace interventions less frequently reach shift workers. The aim was therefore to investigate whether....... The questions concerned usual working hours, quality of leadership, and self-reported implementation of workplace activities aimed at stress reduction, reorganization of the working hours, and participation in improvements of working procedures or qualifications. RESULTS: Compared with day workers, shift...
Lee, Jihyun; Pizzol, Massimo; Thomsen, Marianne
the different background exposure between two countries allows in fact the definition of a common framework for improving exposure scenarios within REACH system, for monitoring environmental health, and for increasing degree of circularity of resource and substance flows. References 1. European Commission...... instruments to support a precautionary chemicals management system and to protect receptor’s health have also been increasing. Since 2007, the European Union adopted REACH (the Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals): REACH makes industry responsible for assessing...... and managing the risks posed by industrial chemicals and providing appropriate safety information to their users (EC, 2007). However, to ensure a high level of protection of human health and the environment, there is a need to consider ‘aggregate exposure’ including background exposures from environment which...
De Graaff, R.; Forbes, S.; Gennart, J.P.; Gimeno Cortes, M.J.; Hovius, H.; King, D.; Kleise, H.; Martinez Martin, C.; Montanari, L.; Pinzuti, M.; Pollack, H.; Ruggieri, P.; Thomas, M.; Walton, A.; Dmytrasz, B.
The purpose of this report is to summarise the findings of the scientific and technical work undertaken by CONCAWE to assess the feasibility and potential benefit of characterising petroleum UVCB substances (Substances of Unknown or Variable Composition, Complex reaction products or Biological Materials) beyond the recommendations issued by CONCAWE for the substance identification of petroleum substances under REACH. REACH is the European Community Regulation on chemicals and their safe use (EC 1907/2006). It deals with the Registration, Evaluation, Authorisation and Restriction of Chemical substances. The report is based on Member Company experience of the chemical analysis of petroleum UVCB substances, including analysis in support of REACH registrations undertaken in 2010. This report is structured into four main sections, namely: Section 1 which provides an introduction to the subject of petroleum UVCB substance identification including the purpose of the report, regulatory requirements, the nature of petroleum UVCB substances, and CONCAWE's guidance to Member Companies and other potential registrants. Section 2 provides a description of the capabilities of each of the analytical techniques described in the REACH Regulation. This section also includes details on the type of analytical information obtained by each technique and an evaluation of what each technique can provide for the characterisation of petroleum UVCB substances. Section 3 provides a series of case studies for six petroleum substance categories (low boiling point naphthas, kerosene, heavy fuel oils, other lubricant base oils, residual aromatic extracts and bitumens) to illustrate the value of the information derived from each analytical procedure, and provide an explanation for why some techniques are not scientifically necessary. Section 4 provides a summary of the conclusions reached from the technical investigations undertaken by CONCAWE Member Companies, and summarising the
Uldam, Julie; McCurdy, Patrick
The research method of participant observation has long been used by scholars interested in the motivations, dynamics, tactics and strategies of social movements from a movement perspective. Despite participant observation being a common research method, there have been very few efforts to bring...... and then draws specific links to how the method has been used in the study of activism and social movements. In doing so, this article brings together key academic debates on participant observation, which have been considered separately, such as insider/outsider and overt/covert, but not previously been brought...
Brown, Theodore M; Fee, Elizabeth
Most public health practitioners know that public health has relied on biomedical advances and administrative improvements, but it is less commonly understood that social movements in health have also been sources of motivation for population health advances. This review considers the impacts of social movements focused on urban conditions and health, on the health of children, and on behavioral and substance-related determinants of health and illustrates how these movements have significantly influenced public health activities and programs. We hope this review will motivate public health workers to make common cause with social activists and to encourage social activists to ally with public health professionals.
Vestenskov, David; Drewes, Line
The conference report Guiding Warfare to Reach Sustainable Peace constitutes the primary outcome of the conference It is based on excerpts from the conference presenters and workshop discussions. Furthermore, the report contains policy recommendations and key findings, with the ambition of develo......The conference report Guiding Warfare to Reach Sustainable Peace constitutes the primary outcome of the conference It is based on excerpts from the conference presenters and workshop discussions. Furthermore, the report contains policy recommendations and key findings, with the ambition...... of developing best practices in the education and implementation of IHL in capacity building of security forces....
Full Text Available After several decades of research on the subject, we now know when the first livestock reached southern Africa but the question of how they got there remains a contentious topic. Debate centres on whether they were brought with a large migration of Khoe-speakers who originated from East Africa; or whether the livestock were traded down-the-line among hunter-gatherer communities; or indeed whether there was a long history of diverse small scale population movements in this part of the world, one or more of which 'infiltrated' livestock into southern Africa. A new analysis of the distribution of stone toolkits from a sizeable sample of sub-equatorial African Later Stone Age sites, coupled with existing knowledge of the distribution of the earliest livestock remains and ceramics vessels, has allowed us to isolate two separate infiltration events that brought the first livestock into southern Africa just over 2000 years ago; one infiltration was along the Atlantic seaboard and another entered the middle reaches of the Limpopo River Basin. These findings agree well with the latest results of genetic research which together indicate that multiple, small-scale infiltrations probably were responsible for bringing the first livestock into southern Africa.
Cressman, Erin K; Henriques, Denise Y P
Visuomotor learning results in changes in both motor and sensory systems (Cressman EK, Henriques DY. J Neurophysiol 102: 3505-3518, 2009), such that reaches are adapted and sense of felt hand position recalibrated after reaching with altered visual feedback of the hand. Moreover, visuomotor learning has been shown to generalize such that reach adaptation achieved at a trained target location can influence reaches to novel target directions (Krakauer JW, Pine ZM, Ghilardi MF, Ghez C. J Neurosci 20: 8916-8924, 2000). We looked to determine whether proprioceptive recalibration also generalizes to novel locations. Moreover, we looked to establish the relationship between reach adaptation and changes in sense of felt hand position by determining whether proprioceptive recalibration generalizes to novel targets in a similar manner as reach adaptation. On training trials, subjects reached to a single target with aligned or misaligned cursor-hand feedback, in which the cursor was either rotated or scaled in extent relative to hand movement. After reach training, subjects reached to the training target and novel targets (including targets from a second start position) without visual feedback to assess generalization of reach adaptation. Subjects then performed a proprioceptive estimation task, in which they indicated the position of their hand relative to visual reference markers placed at similar locations as the trained and novel reach targets. Results indicated that shifts in hand position generalized across novel locations, independent of reach adaptation. Thus these distinct sensory and motor generalization patterns suggest that reach adaptation and proprioceptive recalibration arise from independent error signals and that changes in one system cannot guide adjustments in the other.
Nolan, Maureen; Tschirhart, Lori; Wright, Stephanie; Barrett, Laura; Parsons, Matthew; Whang, Linda
As more users access library services remotely, it has become increasingly important for librarians to reach out to their user communities and promote the value of libraries. Convincing the faculty and students in the sciences of the value of libraries and librarians can be a particularly "hard sell" as more and more of their primary…
Sierra Health Foundation, 2011
Believing in the value of using video documentaries and data as learning tools, members of the REACH technical assistance team collaborated to develop this toolkit. The learning toolkit was designed using and/or incorporating components of the "Engaging Youth in Community Change: Outcomes and Lessons Learned from Sierra Health Foundation's…
Smith, Gene; And Others
As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this postsecondary student manual contains individualized instructional units in the area of electricity. The instructional units focus on electricity fundamentals, electric motors, electrical components, and controls and installation.…
Schinkel, J.; Fransman, W.; McDonnell, P.E.; Entink, R.K.; Tielemans, E.; Kromhout, H.
Objectives: The aim of this study was to assess the reliability of the Advanced REACH Tool (ART) by (i) studying interassessor agreement of the resulting exposure estimates generated by the ART mechanistic model, (ii) studying interassessor agreement per model parameters of the ART mechanistic model
Malinzak, R. Michael; Booth, Gary N.
Springy abrasive tool used to finish surfaces of narrow cavities made by electrical-discharge machining. Robot arm moves vibrator around perimeters of cavities, polishing walls of cavities as it does so. Tool needed because such cavities inaccessible or at least difficult to reach with most surface-finishing tools.
Â OnÂ 9 November the barrel toroid magnet reached its nominal field of 4 teslas, with an electrical current of 21 000 amperes (21 kA) passing through the eight superconducting coils as shown on this graph
Galati, Gaspare; Committeri, Giorgia; Pitzalis, Sabrina; Pelle, Gina; Patria, Fabiana; Fattori, Patrizia; Galletti, Claudio
In the monkey posterior parietal cortex (PPC), there is clear evidence of anatomically segregated neuronal populations specialized for planning saccades and arm-reaching movements. However, functional neuroimaging studies in humans have yielded controversial results. Here we show that the human PPC contains distinct subregions responsive to salient visual cues, some of which combine spatial and action-related signals into 'intentional' signals. Participants underwent event-related functional magnetic resonance imaging while performing delayed saccades and long-range arm reaches instructed by visual cues. We focused on activity in the time period following the cue and preceding the actual movement. The use of individual cortical surface reconstructions with detailed sulcal labeling allowed the definition of six responsive regions with distinctive anatomical locations in the PPC. Each region exhibited a distinctive combination of transient and sustained signals during the delay, modulated by either the cue spatial location (contralateral vs. ipsilateral), the instructed action (saccades vs. reaching) or both. Importantly, a lateral and a medial dorsal parietal region showed sustained responses during the delay preferentially for contralateral saccadic and reaching trials, respectively. In the lateral region, preference for saccades was evident only as a more sustained response during saccadic vs. reaching delays, whereas the medial region also showed a higher transient response to cues signaling reaching vs. saccadic actions. These response profiles closely match the behavior of neurons in the macaque lateral and medial intraparietal area, respectively, and suggest that these corresponding human regions are encoding spatially directed action plans or 'intentions'.
DeLuca, Stephanie C; Ramey, Sharon Landesman; Trucks, Mary Rebekah; Wallace, Dorian Ainsworth
Pediatric constraint-induced movement therapy (pCIMT) is one of the most efficacious treatments for children with cerebral palsy (CP). Distinctive components of pCIMT include constraint of the less impaired upper extremity (UE), high-intensity therapy for the more impaired UE (≥ 3 hr/day, many days per week, for multiple weeks), use of shaping techniques combined with repetitive task practice, and bimanual transfer. A critical issue is whether multiple treatments of pCIMT produce additional benefit. In a clinical cohort (mean age = 31 mo) of 28 children with asymmetrical CP whose parents sought multiple pCIMT treatments, the children gained a mean of 13.2 (standard deviation [SD] = 4.2) new functional skills after Treatment 1; Treatment 2 produced a mean of 7.3 (SD = 4.7) new skills; and Treatment 3, 6.5 (SD = 4.2). These findings support the conclusion that multiple pCIMT treatments can produce clinically important functional gains for children with hemiparetic CP.
Hansen, Lennard Højbjerg
It has been an accepted precept in film theory that specific stylistic features do not express specific content. Nevertheless, it is possible to find many examples in the history of film in which stylistic features do express specific content: for instance, the circular camera movement is used...... such as the circular camera movement. Keywords: embodied perception, embodied style, explicit narration, interpretation, style pattern, television style...
Full Text Available The perceptual localization of an object is often more prone to illusions than an immediate visuomotor action towards that object. The induced Roelofs effect (IRE probes the illusory influence of task-irrelevant visual contextual stimuli on the processing of task-relevant visuospatial instructions during movement preparation. In the IRE, the position of a task-irrelevant visual object induces a shift in the localization of a visual target when subjects indicate the position of the target by verbal response, key-presses or delayed pointing to the target (‘perception’ tasks, but not when immediately pointing or reaching towards it without instructed delay (‘action’ tasks. This discrepancy was taken as evidence for the dual-visual-stream or perception-action hypothesis, but was later explained by a phasic distortion of the egocentric spatial reference frame which is centered on subjective straight-ahead and used for reach planning. Both explanations critically depend on delayed movements to explain the IRE for action tasks. Here we ask: first, if the IRE can be observed for short-latency reaches; second, if the IRE in fact depends on a distorted egocentric frame of reference. Human subjects were tested in new versions of the IRE task in which the reach goal had to be localized with respect to another object, i.e., in an allocentric reference frame. First, we found an IRE even for immediate reaches in our allocentric task, but not for an otherwise similar egocentric control task. Second, the IRE depended on the position of the task-irrelevant frame relative to the reference object, not relative to subjective straight-ahead. We conclude that the IRE for reaching does not mandatorily depend on prolonged response delays, nor does it depend on motor planning in an egocentric reference frame. Instead, allocentric encoding of a movement goal is sufficient to make immediate reaches susceptible to IRE, underlining the context dependence of
Romy S Bakker
Full Text Available The human movement repertoire is characterized by the smooth coordination of several body parts, including arm movements and whole body motion. The neural control of this coordination is quite complex because the various body parts have their own kinematic and dynamic properties. Behavioral inferences about the neural solution to the coordination problem could be obtained by examining the emerging phase relationship and its stability. Here, we studied the phase relationships that characterize the coordination of arm-reaching movements with passively-induced whole-body motion. Participants were laterally translated using a vestibular chair that oscillated at a fixed frequency of 0.83 Hz. They were instructed to reach between two targets that were aligned either parallel or orthogonal to the whole body motion. During the first cycles of body motion, a metronome entrained either an in-phase or an anti-phase relationship between hand and body motion, which was released at later cycles to test phase stability. Results suggest that inertial forces play an important role when coordinating reaches with cyclic whole-body motion. For parallel reaches, we found a stable in-phase and an unstable anti-phase relationship. When the latter was imposed, it readily transitioned or drifted back toward an in-phase relationship at cycles without metronomic entrainment. For orthogonal reaches, we did not find a clear difference in stability between in-phase and anti-phase relationships. Computer simulations further show that cost models that minimize energy expenditure (i.e. net torques or endpoint variance of the reach cannot fully explain the observed coordination patterns. We discuss how predictive control and impedance control processes could be considered important mechanisms underlying the rhythmic coordination of arm reaches and body motion.
Stienen Arno HA
Full Text Available Abstract Background In many stroke patients arm function is limited, which can be related to an abnormal coupling between shoulder and elbow joints. The extent to which this can be translated to activities of daily life (ADL, in terms of muscle activation during ADL-like movements, is rather unknown. Therefore, the present study examined the occurrence of abnormal coupling on functional, ADL-like reaching movements of chronic stroke patients by comparison with healthy persons. Methods Upward multi-joint reaching movements (20 repetitions at a self-selected speed to resemble ADL were compared in two conditions: once facilitated by arm weight compensation and once resisted to provoke a potential abnormal coupling. Changes in movement performance (joint angles and muscle activation (amplitude of activity and co-activation between conditions were compared between healthy persons and stroke patients using a repeated measures ANOVA. Results The present study showed slight changes in joint excursion and muscle activation of stroke patients due to shoulder elevation resistance during functional reach. Remarkably, in healthy persons similar changes were observed. Even the results of a sub-group of the more impaired stroke patients did not point to an abnormal coupling between shoulder elevation and elbow flexion during functional reach. Conclusions The present findings suggest that in mildly and moderately affected chronic stroke patients ADL-like arm movements are not substantially affected by abnormal synergistic coupling. In this case, it is implied that other major contributors to limitations in functional use of the arm should be identified and targeted individually in rehabilitation, to improve use of the arm in activities of daily living.
Full Text Available Throughout the history of the modern world-system, projects of globalization promoted by world elites have been met with resistance from people on the ground whose livelihoods have often been threatened. As the geographic scale of global capitalism has expanded, and its penetration into daily life has deepened, the scale and intensity of resistance to this system has grown as well. Local e?orts to protect traditional ways of life, for instance, have evolved into national campaigns for union protections and then into international movements for stronger labor, human rights, and environmental protections. Today, as global elites push for the ?nal incorporation of all regions into a single capitalist system based on neoliberal principles, they are being met by an unexpectedly resilient, far-reaching, and multi-faceted coalition of resistance. Whatever it may be calledthe anti-globalization movement, the global solidarity movement, or the globalization protest movementit is clear that this anti-systemic movement has emerged as an important challenger to the dominance of global capital over the contemporary world.
Full Text Available Mirror movement is an interesting but often overlooked neurological soft sign;these movements are described as simultaneous contralateral, involuntary, identical movements that accompany voluntary movements. This neurologic problem is very rarely seen in children; in familial cases there is a positive history of these movements in parents, diminishing with time. Here, we have presented the case of an 11-year old girl with mirror movements in her upper limbs which interfered with her hand writing. Her neurological examination revealed normal results. In this report, we have tried to explain some of the pathophysiologic mechanisms related to these abnormal movements.Keywords:Mirror Movements, Children, Soft neurologic sign
Ryan, Jennifer D; Riggs, Lily; McQuiggan, Douglas A; McQuiggan, Doug
Explicit (often verbal) reports are typically used to investigate memory (e.g. "Tell me what you remember about the person you saw at the bank yesterday."), however such reports can often be unreliable or sensitive to response bias, and may be unobtainable in some participant populations. Furthermore, explicit reports only reveal when information has reached consciousness and cannot comment on when memories were accessed during processing, regardless of whether the information is subsequently accessed in a conscious manner. Eye movement monitoring (eye tracking) provides a tool by which memory can be probed without asking participants to comment on the contents of their memories, and access of such memories can be revealed on-line. Video-based eye trackers (either head-mounted or remote) use a system of cameras and infrared markers to examine the pupil and corneal reflection in each eye as the participant views a display monitor. For head-mounted eye trackers, infrared markers are also used to determine head position to allow for head movement and more precise localization of eye position. Here, we demonstrate the use of a head-mounted eye tracking system to investigate memory performance in neurologically-intact and neurologically-impaired adults. Eye movement monitoring procedures begin with the placement of the eye tracker on the participant, and setup of the head and eye cameras. Calibration and validation procedures are conducted to ensure accuracy of eye position recording. Real-time recordings of X,Y-coordinate positions on the display monitor are then converted and used to describe periods of time in which the eye is static (i.e. fixations) versus in motion (i.e., saccades). Fixations and saccades are time-locked with respect to the onset/offset of a visual display or another external event (e.g. button press). Experimental manipulations are constructed to examine how and when patterns of fixations and saccades are altered through different types of prior
Nabe-Nielsen, Kirsten; Garde, Anne Helene; Clausen, Thomas;
OBJECTIVES: One reason for health disparities between shift and day workers may be that workplace health promotion does not reach shift workers to the same extent as it reaches day workers. This study aimed to investigate the association between shift work and the availability of and participation...... in workplace health promotion. METHODS: We used cross-sectional questionnaire data from a large representative sample of all employed people in Denmark. We obtained information on the availability of and participation in six types of workplace health promotion. We also obtained information on working hours, ie......). RESULTS: In the general working population, fixed evening and fixed night workers, and employees working variable shifts including night work reported a higher availability of health promotion, while employees working variable shifts without night work reported a lower availability of health promotion...
Penman, Mike; Banton, Marcy; Erler, Steffen; Moore, Nigel; Semmler, Klaus
REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) is the European Union's chemical regulation for the management of risk to human health and the environment (European Chemicals Agency, 2006). This regulation entered into force in June 2007 and required manufacturers and importers to register substances produced in annual quantities of 1000 tonnes or more by December 2010, with further deadlines for lower tonnages in 2013 and 2018. Depending on the type of registration, required information included the substance's identification, the hazards of the substance, the potential exposure arising from the manufacture or import, the identified uses of the substance, and the operational conditions and risk management measures applied or recommended to downstream users. Among the content developed to support this information were Derived No-Effect Levels or Derived Minimal Effect Levels (DNELs/DMELs) for human health hazard assessment, Predicted No Effect Concentrations (PNECs) for environmental hazard assessment, and exposure scenarios for exposure and risk assessment. Once registered, substances may undergo evaluation by the European Chemicals Agency (ECHA) or Member State authorities and be subject to requests for additional information or testing as well as additional risk reduction measures. To manage the REACH registration and related activities for the European olefins and aromatics industry, the Lower Olefins and Aromatics REACH Consortium was formed in 2008 with administrative and technical support provided by Penman Consulting. A total of 135 substances are managed by this group including 26 individual chemical registrations (e.g. benzene, 1,3-butadiene) and 13 categories consisting of 5-26 substances. This presentation will describe the content of selected registrations prepared for 2010 in addition to the significant post-2010 activities. Beyond REACH, content of the registrations may also be relevant to other European activities, for
Aoki, Takashi; Lin, Jonathan Feng-Shun; Kulic, Dana; Venture, Gentiane
This paper proposes an approach for the segmentation of human body movements measured by inertial measurement unit sensors. Using the angular velocity and linear acceleration measurements directly, without converting to joint angles, we perform segmentation by formulating the problem as a classification problem, and training a classifier to differentiate between motion end-point and within-motion points. The proposed approach is validated with experiments measuring the upper body movement during reaching tasks, demonstrating classification accuracy of over 85.8%.
Bent, Nicholas P.; Rushton, Alison B.; Wright, Chris C.; Batt, Mark E.
The Anteromedial Reach Test (ART) is a new outcome measure for assessing dynamic knee stability in anterior cruciate ligament-injured patients. The effect of learning and leg length on distance reached in the ART was examined. Thirty-two healthy volunteers performed 15 trials of the ART on each leg. There was a moderate correlation (r = 0.44-0.50)…
Holmes, Nicholas P; Dakwar, Azar R
Movements aimed towards objects occasionally have to be adjusted when the object moves. These online adjustments can be very rapid, occurring in as little as 100ms. More is known about the latency and neural basis of online control of movements to visual than to auditory target objects. We examined the latency of online corrections in reaching-to-point movements to visual and auditory targets that could change side and/or modality at movement onset. Visual or auditory targets were presented on the left or right sides, and participants were instructed to reach and point to them as quickly and as accurately as possible. On half of the trials, the targets changed side at movement onset, and participants had to correct their movements to point to the new target location as quickly as possible. Given different published approaches to measuring the latency for initiating movement corrections, we examined several different methods systematically. What we describe here as the optimal methods involved fitting a straight-line model to the velocity of the correction movement, rather than using a statistical criterion to determine correction onset. In the multimodal experiment, these model-fitting methods produced significantly lower latencies for correcting movements away from the auditory targets than away from the visual targets. Our results confirm that rapid online correction is possible for auditory targets, but further work is required to determine whether the underlying control system for reaching and pointing movements is the same for auditory and visual targets.
Ganos, C; Edwards, M J; Bhatia, K P
Traumatic injury to the nervous system may account for a range of neurologic symptoms. Trauma location and severity are important determinants of the resulting symptoms. In severe head injury with structural brain abnormalities, the occurrence of trauma-induced movement disorders, most commonly hyperkinesias such as tremor and dystonia, is well recognized and its diagnosis straightforward. However, the association of minor traumatic events, which do not lead to significant persistent structural brain damage, with the onset of movement disorders is more contentious. The lack of clear clinical-neuroanatomic (or symptom lesion) correlations in these cases, the variable timing between traumatic event and symptom onset, but also the presence of unusual clinical features in a number of such patients, which overlap with signs encountered in patients with functional neurologic disorders, contribute to this controversy. The purpose of this chapter is to provide an overview of the movement disorders, most notably dystonia, that have been associated with peripheral trauma and focus on their unusual characteristics, as well as their overlap with functional neurologic disorders. We will then provide details on pathophysiologic views that relate minor peripheral injuries to the development of movement disorders and compare them to knowledge from primary organic and functional movement disorders. Finally, we will comment on the appropriate management of these disorders.
Constand, Marissa K; MacDermid, Joy C
Background Reaching overhead and reading are tasks that many individuals encounter daily. The level of difficulty of these tasks increases if an individual has neck pain. This study determined the neck movement patterns during these two tasks by comparing neck flexion of individuals with and without neck pain. Methods This case control study used the portable video technology, Dartfish ProSuite 5.5 Video Software, to analyse neck flexion movement patterns. Healthy individuals and individuals ...
Full Text Available Muscle activities underlying many motor behaviors can be generated by a small number of basic activation patterns with specific features shared across movement conditions. Such low-dimensionality suggests that the central nervous system (CNS relies on a modular organization to simplify control. However, the relationship between the dimensionality of muscle patterns and that of joint torques is not fixed, because of redundancy and non-linearity in mapping the former into the latter, and needs to be investigated. We compared the torques acting at four arm joints during fast reaching movements in different directions in the frontal and sagittal planes and the underlying muscle patterns. The dimensionality of the non-gravitational components of torques and muscle patterns in the spatial, temporal, and spatiotemporal domains was estimated by multidimensional decomposition techniques. The spatial organization of torques was captured by two or three generators, indicating that not all the available coordination patterns are employed by the CNS. A single temporal generator with a biphasic profile was identified, generalizing previous observations on a single plane. The number of spatiotemporal generators was equal to the product of the spatial and temporal dimensionalities and their organization was essentially synchronous. Muscle pattern dimensionalities were higher than torques dimensionalities but also higher than the minimum imposed by the inherent non-negativity of muscle activations. The spatiotemporal dimensionality of the muscle patterns was lower than the product of their spatial and temporal dimensionality, indicating the existence of specific asynchronous coordination patterns. Thus, the larger dimensionalities of the muscle patterns may be required for CNS to overcome the non-linearities of the musculoskeletal system and to flexibly generate endpoint trajectories with simple kinematic features using a limited number of building blocks.
Albrecht, Stan L.
An effort to select an important contemporary social movement (the environmental movement) and to assess some of the important impacts it has had on the larger society. This review of the environmental movement indicates it may be following a path similiar to the life-cycle of previous movements. (Author/BT)
Couton, Philippe; López, José Julián
Opposition to utopianism on ontological and political grounds has seemingly relegated it to a potentially dangerous form of antiquated idealism. This conclusion is based on a restrictive view of utopia as excessively ordered panoptic discursive constructions. This overlooks the fact that, from its inception, movement has been central to the utopian tradition. The power of utopianism indeed resides in its ability to instantiate the tension between movement and place that has marked social transformations in the modern era. This tension continues in contemporary discussions of movement-based social processes, particularly international migration and related identity formations, such as open borders transnationalism and cosmopolitanism. Understood as such, utopia remains an ongoing and powerful, albeit problematic instrument of social and political imagination.
Full Text Available We have shown that when subjects reach with continuous, misaligned visual feedback of their hand, their reaches are adapted and proprioceptive sense of hand position is recalibrated to partially match the visual feedback (Salomonczyk et al., 2011. It is unclear if similar changes arise after reaching with visual feedback that is provided only at the end of the reach (i.e., terminal feedback, when there are shorter temporal intervals for subjects to experience concurrent visual and proprioceptive feedback. Subjects reached to targets with an aligned hand-cursor that provided visual feedback at the end of each reach movement across a 99-trial training block, and with a rotated cursor over 3 successive blocks of 99 trials each. After each block, no cursor reaches, to measure aftereffects, and felt hand positions were measured. Felt hand position was determined by having subjects indicate the position of their unseen hand relative to a reference marker. We found that subjects adapted their reaches following training with rotated terminal visual feedback, yet slightly less (i.e., reach aftereffects were smaller, than subjects from a previous study who experienced continuous visual feedback. Nonetheless, current subjects recalibrated their sense of felt hand position in the direction of the altered visual feedback, but this proprioceptive change increased incrementally over the three rotated training blocks. Final proprioceptive recalibration levels were comparable to our previous studies in which subjects performed the same task with continuous visual feedback. Thus, compared to reach training with continuous, but altered visual feedback, subjects who received terminal altered visual feedback of the hand produced significant but smaller reach aftereffects and similar changes in hand proprioception when given extra training. Taken together, results suggest that terminal feedback of the hand is sufficient to drive motor adaptation, and also
e Silva, E. Costa; Costa, M. F.; Bicho, E.; Erlhagen, W.
Human-like movement is fundamental for natural human-robot interaction and collaboration. We have developed in a model for generating arm and hand movements an anthropomorphic robot. This model was inspired by the Posture-Based Motion-Planning Model of human reaching and grasping movements. In this paper we present some changes to the model we have proposed in  and test and compare different nonlinear constrained optimization techniques for solving the large-scale nonlinear constrained optimization problem that rises from the discretization of our time-continuous model. Furthermore, we test different time discretization steps.
Alaverdashvili, M; Whishaw, I Q
Compensatory movements mediate success in skilled reaching for food after stroke to the forelimb region of motor cortex (MtCx) in the rat. The present study asks whether the neural plasticity that enables compensation after motor stroke is preserved in aging. In order to avoid potential confounding effects of age-related negative-learning, rats were trained in a single pellet reaching task during young-adulthood. Subgroups were retested before and after contralateral forelimb MtCx stroke via pial stripping given at 3, 18, or 23 months of age. Over a two-month post-stroke rehabilitation period, end point measures were made of learned nonuse, recovery, retention, and performance ratings were made of reaching movement elements. Prior to stroke, young and aged rats maintained equivalent end point performance but older rats displayed compensatory changes in limb use as measured with ratings of the elements of forelimb movement. Following stroke, the aged groups of rats were more impaired on end point, movement, and anatomical measures. Nevertheless, the aged rats displayed substantial recovery via the use of compensatory movements. Thus, this study demonstrates that the neural plasticity that mediates compensatory movements after stroke in young adults is preserved prior to and following stroke in aging.
Trombly, C A
Kinematic analysis and surface electromyography were used to study reaching by five subjects with left hemiparesis as they attempted to touch each of three targets. The targets were placed to require movement within and out of extensor synergy. Each subject was tested five times over a nine week period. Over this time, amplitude of peak velocity and sense of limb position significantly improved in the paretic arms. The increase of amplitude of peak velocity was more strongly related to a decrease in the discontinuity of movement (r = -0.48) than to maximal level of contraction of the prime movers (anterior deltoid: r = 0.25; biceps: r = 0.39). This finding may be a sign of learning or increased maturity of reach. These results, if replicated in a larger sample, would support therapy designed to improve learning of new sensorimotor relationships in the hemiparetic limb.
Pompea, Stephen M.; Sparks, R. T.; Walker, C. E.
NOAO education programs are designed to reach diverse audiences. Examples described in this poster include the Hands-On Optics Project nationwide, an extension of the Hands-On Optics program at Boys and Girls Clubs in Arizona and in Hawaii, a professional development program for Navajo and Hopi teachers, a number of programs for the Tohono O'odham Nation, and a project collecting and reviewing Spanish language astronomy materials. Additionally NOAO is also involved in several local outreach projects for diverse and underserved audiences.
Kinematic analysis and surface electromyography were used to study reaching by five subjects with left hemiparesis as they attempted to touch each of three targets. The targets were placed to require movement within and out of extensor synergy. Each subject was tested five times over a nine week period. Over this time, amplitude of peak velocity and sense of limb position significantly improved in the paretic arms. The increase of amplitude of peak velocity was more strongly related to a decr...
Nazzal, G. (Eastman Teleco, Houston, TX (United States))
Extended-reach drilling (ERD) is being used to exploit fields and reserves that are located far from existing platforms. Effective wellbore placement from fewer platforms can reduce development costs, maximize production and increase reserve recovery. Six wells drilled offshore in the US, North Sea and Australia illustrate how to get the most economic benefit from available infrastructure. These wells are divided into three categories by depth (shallow, medium and deep). Vertical depth of these wells range from 963 to 12,791 ft TVD and displacements range from 4,871 to 23,917 ft. Important factors for successful extended-reach drilling included: careful, comprehensive pre-planning; adequate cuttings removal in all sections; hole stability in long, exposed intervals; torque and drag modeling of drilling BHAs, casing and liners; buoyancy-assisted casing techniques where appropriate; critical modifications to drilling rig and top drive, for medium and deep ERD; modified power swivels for shallow operations; drill pipe rubbers or other casing protection during extended periods of drill string rotation; heavy-wall casting across anticipated high-wear areas; survey accuracy and frequency; sound drilling practices and creativity to accomplish goals and objectives. This paper reviews the case history of these sites and records planning and design procedures.
Cooper, Crystale Purvis; Gelb, Cynthia A; Chu, Jennifer; Polonec, Lindsey
Donated media placements for public service announcements (PSAs) can be difficult to secure, and may not always reach intended audiences. Strategies used by the Centers for Disease Control and Prevention's (CDC) Screen for Life: National Colorectal Cancer Action Campaign (SFL) to obtain donated media placements include producing a diverse mix of high-quality PSAs, co-branding with state and tribal health agencies, securing celebrity involvement, monitoring media trends to identify new distribution opportunities, and strategically timing the release of PSAs. To investigate open-ended recall of PSAs promoting colorectal cancer screening, CDC conducted 12 focus groups in three U.S. cities with men and women either nearing age 50 years, when screening is recommended to begin, or aged 50-75 years who were not in compliance with screening guidelines. In most focus groups, multiple participants recalled exposure to PSAs promoting colorectal cancer screening, and most of these individuals reported having seen SFL PSAs on television, in transit stations, or on the sides of public buses. Some participants reported exposure to SFL PSAs without prompting from the moderator, as they explained how they learned about the disease. Several participants reported learning key campaign messages from PSAs, including that colorectal cancer screening should begin at age 50 years and screening can find polyps so they can be removed before becoming cancerous. Donated media placements can reach and educate mass audiences, including millions of U.S. adults who have not been screened appropriately for colorectal cancer.
Information about the SFBWQP Napa River Restoration Project: Rutherford Reach Completion/Oakville to Oak Knoll, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.
Carmichael, Karla D.
This paper's premise is that music, movement, and poetry are unique and creative methods to be used by the counselor in working with both children and adults. Through these media, the counselor generates material for the counseling session that may not be available through more traditional "talk therapies." The choice of music as a counseling…
Like many other African countries, Kenya has a large and growing youth population. Some of the youths are mobilized into militant and political networks; one of these is the Mungiki movement. The article explores Mungiki’s combination of politics, religion and Kikuyu traditions. Using the examples...
Mckeon, Andrew; Vincent, Angela
Autoimmune movement disorders encapsulate a large and diverse group of neurologic disorders occurring either in isolation or accompanying more diffuse autoimmune encephalitic illnesses. The full range of movement phenomena has been described and, as they often occur in adults, many of the presentations can mimic neurodegenerative disorders, such as Huntington disease. Disorders may be ataxic, hypokinetic (parkinsonism), or hyperkinetic (myoclonus, chorea, tics, and other dyskinetic disorders). The autoantibody targets are diverse and include neuronal surface proteins such as leucine-rich, glioma-inactivated 1 (LGI1) and glycine receptors, as well as antibodies (such as intracellular antigens) that are markers of a central nervous system process mediated by CD8+ cytotoxic T cells. However, there are two conditions, stiff-person syndrome (also known as stiff-man syndrome) and progressive encephalomyelitis with rigidity and myoclonus (PERM), that are always autoimmune movement disorders. In some instances (such as Purkinje cell cytoplasmic antibody-1 (PCA-1) autoimmunity), antibodies detected in serum and cerebrospinal fluid can be indicative of a paraneoplastic cause, and may direct the cancer search. In other instances (such as 65kDa isoform of glutamic acid decarboxylase (GAD65) autoimmunity), a paraneoplastic cause is very unlikely, and early treatment with immunotherapy may promote improvement or recovery. Here we describe the different types of movement disorder and the clinical features and antibodies associated with them, and discuss treatment.
Ekman, Paul; Friesen, Wallace V.
The Facial Action Code (FAC) was derived from an analysis of the anatomical basis of facial movement. The development of the method is explained, contrasting it to other methods of measuring facial behavior. An example of how facial behavior is measured is provided, and ideas about research applications are discussed. (Author)
Full Text Available Psychogenic movement Disorders (PMD may result from somatoform disorders, factitious disorders, malingering, depression anxiety disorders and less frequently, histrionic personality disorders. First recognized by Henry Head in early twentieth century, PMD s commonly encountered and clues to their differentiation from organic disease. A generally accepted management protocol has been outlined.
Clemmer, Richard O.
Traces development of Hopi Traditionalism since 1906 as a social movement within the context of Hopi culture and sociopolitical history. Discusses the role of ideology in mediating political and economic conditions of history and collective cultural consciousness. Offers conclusions about the political role of indigenous culture and culturally…
Laban, Rudolf; Ullmann, Lisa
In this third edition, some amendments and additions have been made to the original text, first published in 1950. As in past editions, the relationship between the inner motivation of movement and the outer functioning of the body is explored. Acting and dancing are shown as activities deeply concerned with man's urge to establish values and…
Leading an architectural project means accompanying the movement which it induces within the teams. Between questioning, uncertainty and fear, the organisational changes inherent to the new facility must be subject to constructive and ongoing exchanges. Ethics, safety and training are revised and the unit projects are sometimes modified.
Hahonou, Eric Komlavi; Pelckmans, Lotte
-slavery movements had raised awareness, this political emergence was even easier. Indeed the fight against ‘slave mentalities’ was everywhere a major challenge and a crucial step to mobilize groups of slave status under a united force. As this article argues changes in political structures and changes in political...
Cahill-Rowley, Katelyn; Rose, Jessica
Reaching is a well-practiced functional task crucial to daily living activities, and temporal-spatial measures of reaching reflect function for both adult and pediatric populations with upper-extremity motor impairments. Inertial sensors offer a mobile and inexpensive tool for clinical assessment of movement. This research outlines a method for measuring temporal-spatial reach parameters using inertial sensors, and validates these measures with traditional marker-based motion capture. 140 reaches from 10 adults, and 30 reaches from nine children aged 18-20 months, were recorded and analyzed using both inertial-sensor and motion-capture methods. Inertial sensors contained three-axis accelerometers, gyroscopes, and magnetometers. Gravitational offset of accelerometer data was measured when the sensor was at rest, and removed using sensor orientation measured at rest and throughout the reach. Velocity was calculated by numeric integration of acceleration, using a null-velocity assumption at reach start. Sensor drift was neglected given the 1-2s required for a reach. Temporal-spatial reach parameters were calculated independently for each data acquisition method. Reach path length and distance, peak velocity magnitude and timing, and acceleration at contact demonstrated consistent agreement between sensor- and motion-capture-based methods, for both adult and toddler reaches, as evaluated by intraclass correlation coefficients from 0.61 to 1.00. Taken together with actual difference between method measures, results indicate that these functional reach parameters may be reliably measured with inertial sensors.
Full Text Available BACKGROUND: Previous work by our group has shown that the scaling of reach trajectories to target size is independent of obligatory awareness of that target property and that "action without awareness" can persist for up to 2000 ms of visual delay. In the present investigation we sought to determine if the ability to scale reaching trajectories to target size following a delay is related to the pre-computing of movement parameters during initial stimulus presentation or the maintenance of a sensory (i.e., visual representation for on-demand response parameterization. METHODOLOGY/PRINCIPAL FINDINGS: Participants completed immediate or delayed (i.e., 2000 ms perceptual reports and reaching responses to different sized targets under non-masked and masked target conditions. For the reaching task, the limb associated with a trial (i.e., left or right was not specified until the time of response cuing: a manipulation that prevented participants from pre-computing the effector-related parameters of their response. In terms of the immediate and delayed perceptual tasks, target size was accurately reported during non-masked trials; however, for masked trials only a chance level of accuracy was observed. For the immediate and delayed reaching tasks, movement time as well as other temporal kinematic measures (e.g., times to peak acceleration, velocity and deceleration increased in relation to decreasing target size across non-masked and masked trials. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that speed-accuracy relations were observed regardless of whether participants were aware (i.e., non-masked trials or unaware (i.e., masked trials of target size. Moreover, the equivalent scaling of immediate and delayed reaches during masked trials indicates that a persistent sensory-based representation supports the unconscious and metrical scaling of memory-guided reaching.
Bouchard, Ann M [Albuquerque, NM; Osbourn, Gordon C [Albuquerque, NM
A reach and get technique includes invoking a reach command from a reach location within a computing environment. A user can then navigate to an object within the computing environment and invoke a get command on the object. In response to invoking the get command, the computing environment is automatically navigated back to the reach location and the object copied into the reach location.
Svenkeson, A.; Swami, A.
Group decision-making processes often turn into a drawn out and costly battle between two opposing subgroups. Using analytical arguments based on a master equation description of the opinion dynamics occurring in a three-state model of cooperatively interacting units, we show how the capability of a social group to reach consensus can be enhanced when there is an intermediate state for indecisive individuals to pass through. The time spent in the intermediate state must be relatively short compared to that of the two polar states in order to create the beneficial effect. Furthermore, the cooperation between individuals must not be too low, as the benefit to consensus is possible only when the cooperation level exceeds a specific threshold. We also discuss how zealots, agents that remain in one state forever, can affect the consensus among the rest of the population by counteracting the benefit of the intermediate state or making it virtually impossible for an opposition to form.
Hansson, Sven Ove; Rudén, Christina
Due to the large number of chemicals for which toxicological and ecotoxicological information is lacking, priority setting for data acquisition is a major concern in chemicals regulation. In the current European system, two administrative priority-setting criteria are used, namely novelty (i.e., time of market introduction) and production volume. In the proposed Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) system, the novelty criterion is no longer used, and production volume will be the main priority-setting criterion for testing requirements, supplemented in some cases with hazard indications obtained from QSAR modelling. This system for priority setting has severe weaknesses. In this paper we propose that a multicriteria system should be developed that includes at least three additional criteria: chemical properties, results from initial testing in a tiered system, and voluntary testing for which efficient incentives can be created. Toxicological and decision-theoretical research is needed to design testing systems with validated priority-setting mechanisms.
Bartholdy, J.; Billi, P.
A large number of rivers in Tuscany have channel planforms, which are neither straight nor what is usually understood as meandering. In the typical case, they consist of an almost straight, slightly incised main channel fringed with large lateral bars and lunate-shaped embayments eroded into the former flood plain. In the past, these rivers have not been recognised as an individual category and have often been considered to be either braided or meandering. It is suggested here that this type of river planform be termed pseudomeandering. A typical pseudomeandering river (the Cecina River) is described and analysed to investigate the main factors responsible for producing this channel pattern. A study reach (100×300 m) was surveyed in detail and related to data on discharge, channel changes after floods and grain-size distribution of bed sediments. During 18 months of topographic monitoring, the inner lateral bar in the study reach expanded and migrated towards the concave outer bank which, concurrently, retreated by as much as 25 m. A sediment balance was constructed to analyse bar growth and bank retreat in relation to sediment supply and channel morphology. The conditions necessary to maintain the pseudomeandering morphology of these rivers by preventing them from developing a meandering planform, are discussed and interpreted as a combination of a few main factors such as the flashy character of floods, sediment supply (influenced by both natural processes and human impact), the morphological effects of discharges with contrasting return intervals and the short duration of flood events. Finally, the channel response to floods with variable sediment transport capacity (represented by bed shear stress) is analysed using a simple model. It is demonstrated that bend migration is associated with moderate floods while major floods are responsible for the development of chute channels, which act to suppress bend growth and maintain the low sinuosity configuration of
Herzog, Dennis; Krüger, Volker; Grest, Daniel
A common problem in movement recognition is the recognition of movements of a particular type. E.g. pointing movements are of a particular type but differ in terms of the pointing direction. Arm movements with the goal of reaching out and grasping an object are of a particular type but differ...... with the location of the involved object. In this paper, we present an exemplar-based parametric hidden Markov model (PHMM) that is able to recognize and synthesize movements of a particular type. The PHMM is based on exemplar movements that have to be ``demonstrated'' to the system. Recognition and synthesis...... are carried out through locally linear interpolation of the exemplar movements. Experiments are performed with pointing and grasping movements. Synthesis is done based on the object position as parameterization. In case of the recognition, the coordinates of the grasped or pointed at object are recovered. Our...
McDougle, Samuel D; Boggess, Matthew J; Crossley, Matthew J; Parvin, Darius; Ivry, Richard B; Taylor, Jordan A
When a person fails to obtain an expected reward from an object in the environment, they face a credit assignment problem: Did the absence of reward reflect an extrinsic property of the environment or an intrinsic error in motor execution? To explore this problem, we modified a popular decision-making task used in studies of reinforcement learning, the two-armed bandit task. We compared a version in which choices were indicated by key presses, the standard response in such tasks, to a version in which the choices were indicated by reaching movements, which affords execution failures. In the key press condition, participants exhibited a strong risk aversion bias; strikingly, this bias reversed in the reaching condition. This result can be explained by a reinforcement model wherein movement errors influence decision-making, either by gating reward prediction errors or by modifying an implicit representation of motor competence. Two further experiments support the gating hypothesis. First, we used a condition in which we provided visual cues indicative of movement errors but informed the participants that trial outcomes were independent of their actual movements. The main result was replicated, indicating that the gating process is independent of participants' explicit sense of control. Second, individuals with cerebellar degeneration failed to modulate their behavior between the key press and reach conditions, providing converging evidence of an implicit influence of movement error signals on reinforcement learning. These results provide a mechanistically tractable solution to the credit assignment problem.
Johansson, Henrik; Zeidler, Mathias
In response to low or high intensities of light, the chloroplasts in the mesophyll cells of the leaf are able to increase or decrease their exposure to light by accumulating at the upper and lower sides or along the side walls of the cell respectively. This movement, regulated by the phototropin blue light photoreceptors phot1 and phot2, results in a decreased or increased transmission of light through the leaf. This way the plant is able to optimize harvesting of the incoming light or avoid damage caused by excess light. Here we describe a method that indirectly measures the movement of chloroplasts by taking advantage of the resulting change in leaf transmittance. By using a microplate reader, quantitative measurements of chloroplast accumulation or avoidance can be monitored over time, for multiple samples with relatively little hands-on time.
Bos-Huizer, J J A; Bolderman, F W
'Ergonomic movement in dentistry' is a recently developed ergonomic programme for dental healthcare professionals which is intended to prevent work-related complaints and assist in recovering from them. The programme is recommended by disability insurers in cases of specific physical complaints, limitations or disability, as a consequence of which a dental healthcare professional is unable to carry out his or her work. In a four-day training programme, in one's own workplace, skills are taught in the areas of work organization, work attitude and movement. These skills are directly applied in the treatment ofpatients and, if necessary, further improved. In this way, one advances step by step to an ergonomic way of working. Evaluations have shown that the programme is advantageous for the attitude toward work, the workplace and the work organization as well as the reduction of disability.
Full Text Available Review of Spyros Papapetros, On the Animation of the Inorganic: Art, Architecture, and the Extension of Life: Spyros Papapetros examines ideas about simulated movement and inorganic life during and after the turn of the twentieth century. Exploring works of a selection of important art historians as well as artists and architects of the period, the author maintains that the ability to identify with material objects was repressed by modernist culture, and yet found expression stylistically through depictions of inorganic forms. That expression is shown to have continuity with older medieval and renaissance depictions. The book is organized by a narrative that evokes the modes of inquiry documented and critiqued by the content of the book, employing movement as a narrative device, a metaphor, while serving as a subject of inquiry.
Full Text Available Effective telerehabilitation technologies enable patients with certain physiological disabilities to engage in rehabilitative exercises for performing Activities of Daily Living (ADLs. Therefore, training and assessment scenarios for the performance of ADLs are vital for the promotion for telerehabilitation. In this paper we investigate quantitatively and automatically assessing patient’s kinematic ability to perform functional upper extremity reaching tasks. The shape of the movement trajectory and the instantaneous acceleration of kinematically crucial body parts, such as wrists, are used to compute the approximate entropy of the motions to represent stability (smoothness in addition to the duration of the activity. Computer simulations were conducted to illustrate the consistency, sensitivity and robustness of the proposed method. A preliminary experiment with kinematic data captured from healthy subjects mimicking a reaching task with dyskinesia showed a high degree of correlation (Cohen’s kappa 0.85 with p<0.05 between a human observer and the proposed automatic classification tool in terms of assigning the datasets to various levels to represent the subjects’ kinematic abilities to perform reaching tasks. This study supported the use of Microsoft Kinect to quantitatively evaluate the ability of individuals with involuntary movements to perform an upper extremity reaching task.
M. Afzal Upal
Full Text Available This paper argues that in order to win the long-term fight against Islamic Jihadist movements, we must confront their ideological foundations and provide the majority of Muslims with an alternative narrative that satisfies their social identity needs for a positive esteem. By analysing social identity dynamics of Western-Muslim interactions, this paper presents some novel ideas that can lead to the creation of such a narrative.
movement patterns; for example, horses , deer, and javelina exhibit grazing behaviors that are similar to, but not quite the same as, cattle. Individual...conveyance would be modeled. This might be as simple as a person riding a horse , mule, camel, or burro, or as complex as a multiwheeled truck, train...or tracked vehicle. The assumption presented is that each system of conveyance reflects the will of its operator/ rider , whether that system is a
Newman, P. C.
A historical account is given of the spectacular success that was Westcoast Energy Inc., a Canadian natural gas giant that charted a wilderness pipeline from natural gas fields in Canada's sub-arctic solitude. The beginning of the company is traced to an event in 1934 when near the bank of the Pouce Coupe River, close to the Alberta-British Columbia border, Frank McMahon, a solitary wildcatter and the eventual founder of the company, first sighted the fiery inferno of a runaway wildcat well, drilled by geologists of the Imperial Oil Company during their original search for the Canadian petroleum basin's motherlode. It was on this occasion in 1934 that McMahon first conceived a geological profile that connected the gas-bearing sandstone of Pouce Coupe with the reservoir rock of the biggest natural gas field of Alberta, and a pipeline from this sandstone storehouse across the rugged heart of British Columbia to Vancouver, and south into the United States. It took the better part of a quarter century to realize the dream of that pipeline which, in due course, turned out to be only the first step towards reaching the top rank of Canadian corporations in operational and financial terms, and becoming one of only a handful in terms of a story that became a Canadian corporate legend. By chronicling the lives and contributions of the company's founder and senior officials over the years, the book traces the company's meteoric rise from a gleam in its founder's eye to a cautious regional utility, and to the aggressive Canadian adventurer that went on to burst the boundaries of its Pacific Coast world, until the continental reach of its operations and interests run from Canada's Pacific shoreline to its Atlantic basins and Mexico's Campeche Bay to Alaska's Prudhoe Bay. The company's independent existence came to an end in 2002 when Westcoast Energy, by then a $15 billion operation, was acquired by Duke Energy Limited of North
Antonella Del Rosso
On 16 September 2015 at 22:54:33 (UTC), an 8.3-magnitude earthquake struck off the coast of Chile. 11,650 km away, at CERN, a new-generation instrument – the Precision Laser Inclinometer (PLI) – recorded the extreme event. The PLI is being tested by a JINR/CERN/ATLAS team to measure the movements of underground structures and detectors. The Precision Laser Inclinometer during assembly. The instrument has proven very accurate when taking measurements of the movements of underground structures at CERN. The Precision Laser Inclinometer is an extremely sensitive device capable of monitoring ground angular oscillations in a frequency range of 0.001-1 Hz with a precision of 10-10 rad/Hz1/2. The instrument is currently installed in one of the old ISR transfer tunnels (TT1) built in 1970. However, its final destination could be the ATLAS cavern, where it would measure and monitor the fine movements of the underground structures, which can affect the precise posi...
Müller-Vahl, K R; Kolbe, H; Schneider, U; Emrich, H M
Central cannabinoid receptors are densely located in the output nuclei of the basal ganglia (globus pallidus, substantia nigra pars reticulata), suggesting their involvement in the regulation of motor activity. Furthermore, there is evidence that endogenous cannabinoid transmission plays a role in the manipulation of other transmitter systems within the basal ganglia by increasing GABAergic transmission, inhibiting glutamate release and affecting dopaminergic uptake. Most hyperkinetic and hypokinetic movement disorders are caused by a dysfunction of basal ganglia-thalamo-cortical loops. It has been suggested that an endogenous cannabinoid tone participates in the control of movements and, therefore, the central cannabinoid system might play a role in the pathophysiology of these diseases. During the last years in humans a limited number of clinical trials demonstrated that cannabinoids might be useful in the treatment of movement disorders. Despite the lack of controlled studies there is evidence that cannabinoids are of therapeutic value in the treatment of tics in Tourette syndrome, the reduction of levodopa-induced dyskinesia in Parkinson s disease and some forms of tremor and dystonia. It can be speculated that cannabinoid antagonists might be useful in the treatment of chorea in Huntington s disease and hypokinetic parkinsonian syndromes.
LEP's last superconducting module leaves its home port... Just seven months into the operation, LEP dismantling is forging ahead. Two of the eight arcs which form the tunnel have already been emptied and the last of the accelerator's radiofrequency (RF) cavities has just been raised to the surface. The 160 people working on LEP dismantling have reason to feel pleased with their progress. All of the accelerator's 72 superconducting RF modules have already been brought to the surface, with the last one being extracted on 2nd May. This represents an important step in the dismantling process, as head of the project, John Poole, explains. 'This was the most delicate part of the project, because the modules are very big and they could only come out at one place', he says. The shaft at point 1.8 through which the RF cavity modules pass is 18 metres in diameter, while each module is 11.5 metres long. Some modules had to travel more than 10 kilometres to reach the shaft. ... is lifted up the PM 1.8 shaft, after a m...
CERN Courier (september 2011 issue)
After eight years of searching for the emission of a dark matter candidate particle, the axion, from the Sun, the CERN Axion Solar Telescope (CAST) has fulfilled its original physics programme. Members of the CAST collaboration in July, together with dipole-based helioscope. CAST, the world’s most sensitive axion helioscope, points a recycled prototype LHC dipole magnet at the Sun at dawn and dusk, looking for the conversion of axions to X-rays. It incorporates four state-of-the-art X-ray detectors: three Micromegas detectors and a pn-CCD imaging camera attached to a focusing X-ray telescope that was recovered from the German space programme (see CERN Courier April 2010). Over the years, CAST has operated with the magnet bores - the location of the axion conversion - in different conditions: first in vacuum, covering axion masses up to 20 meV/c2, and then with a buffer gas (4He and later 3He) at various densities, finally reaching the goal of 1.17 eV/c2 on 22 ...
The ATLAS Forward Calorimeter working group has reached an important milestone in the production of their detectors. The mechanical assembly of the first electromagnetic module (FCal1C) has been completed at the University of Arizona on February 25, 2002, only ten days after the originally scheduled date. The photo shows the University of Arizona FCal group in the clean room, together with the assembled FCal1C module. The module consists of a stack of 18 round copper plates, each about one inch thick. Each plate is about 90 cm in diameter, and has 12260 precision-drilled holes in it, to accommodate the tube/rod electrode assembly. The machining of the plates, which was done at the Science Technology Center (STC) at Carleton University, Ottawa, Canada, required high precision to allow for easy insertion of the electrode copper tube. The plates have been carefully cleaned at the University of Arizona, to remove any machining residue and metal flakes. This process alone took about eleven weeks. Exactly 122...
Pienciak-Siewert, Alison; Horan, Dylan P; Ahmed, Alaa A
Classical theories of motor learning hypothesize that adaptation is driven by sensorimotor error; this is supported by studies of arm and eye movements that have shown that trial-to-trial adaptation increases with error. Studies of postural control have shown that anticipatory postural adjustments increase with the magnitude of a perturbation. However, differences in adaptation have been observed between the two modalities, possibly due to either the inherent instability or sensory uncertainty in standing posture. Therefore, we hypothesized that trial-to-trial adaptation in posture should be driven by error, similar to what is observed in arm reaching, but the nature of the relationship between error and adaptation may differ. Here we investigated trial-to-trial adaptation of arm reaching and postural control concurrently; subjects made reaching movements in a novel dynamic environment of varying strengths, while standing and holding the handle of a force-generating robotic arm. We found that error and adaptation increased with perturbation strength in both arm and posture. Furthermore, in both modalities, adaptation showed a significant correlation with error magnitude. Our results indicate that adaptation scales proportionally with error in the arm and near proportionally in posture. In posture only, adaptation was not sensitive to small error sizes, which were similar in size to errors experienced in unperturbed baseline movements due to inherent variability. This finding may be explained as an effect of uncertainty about the source of small errors. Our findings suggest that in rehabilitation, postural error size should be considered relative to the magnitude of inherent movement variability.
Taniai, Yoshiaki; Nishii, Jun
When we move our body to perform a movement task, our central nervous system selects a movement trajectory from an infinite number of possible trajectories under constraints that have been acquired through evolution and learning. Minimization of the energy cost has been suggested as a potential candidate for a constraint determining locomotor parameters, such as stride frequency and stride length; however, other constraints have been proposed for a human upper-arm reaching task. In this study, we examined whether the minimum metabolic energy cost model can also explain the characteristics of the upper-arm reaching trajectories. Our results show that the optimal trajectory that minimizes the expected value of energy cost under the effect of signal-dependent noise on motor commands expresses not only the characteristics of reaching movements of typical speed but also those of slower movements. These results suggest that minimization of the energy cost would be a basic constraint not only in locomotion but also in upper-arm reaching.
Van der Fits, IBM; Klip, AWJ; Van Eykern, LA; Hadders-Algra, M
The present study focused on the developmental changes of postural adjustments accompanying reaching movements in healthy infants. We made a longitudinal study of ten infants between 6 and 18 months of age. During each session multiple surface electromyograms of arm, neck, trunk and leg muscles at t
Itaguchi, Yoshihiro; Fukuzawa, Kazuyoshi
The present study investigated the impact of motor commands to abort ongoing movement on position estimation. Participants carried out visually guided reaching movements on a horizontal plane with their eyes open. By setting a mirror above their arm, however, they could not see the arm, only the start and target points. They estimated the position of their fingertip based solely on proprioception after their reaching movement was stopped before reaching the target. The participants stopped reaching as soon as they heard an auditory cue or were mechanically prevented from moving any further by an obstacle in their path. These reaching movements were carried out at two different speeds (fast or slow). It was assumed that additional motor commands to abort ongoing movement were required and that their magnitude was high, low, and zero, in the auditory-fast condition, the auditory-slow condition, and both the obstacle conditions, respectively. There were two main results. (1) When the participants voluntarily stopped a fast movement in response to the auditory cue (the auditory-fast condition), they showed more underestimates than in the other three conditions. This underestimate effect was positively related to movement velocity. (2) An inverted-U-shaped bias pattern as a function of movement distance was observed consistently, except in the auditory-fast condition. These findings indicate that voluntarily stopping fast ongoing movement created a negative bias in the position estimate, supporting the idea that additional motor commands or efforts to abort planned movement are involved with the position estimation system. In addition, spatially probabilistic inference and signal-dependent noise may explain the underestimate effect of aborting ongoing movement.
Buchin, M.; Kruckenberg, H.; Kölzsch, A.; Timpf, S.; Laube, P.
Dividing movement trajectories according to different movement states of animals has become a challenge in movement ecology, as well as in algorithm development. In this study, we revisit and extend a framework for trajectory segmentation based on spatio-temporal criteria for this purpose. We adapt
Frank, U.; Berners, H. [RWE-DEA AG, Hamburg (Germany). Drilling Team Mittelplate und Dieksand; Hadow, A.; Klop, G.; Sickinger, W. [Wintershall AG Erdoelwerke, Barnstdorf (Germany); Sudron, K.
The Mittelplate oil field is located 7 km offshore the town of Friedrichskoog. Reserves are estimated at 30 million tonnes of oil. At a production rate of 2,500 t/d, it will last about 33 years. The transport capacity of the offshore platform is limited, so that attempts were made to enhance production by constructing the extended reach borehole Dieksand 2. Details are presented. (orig.) [Deutsch] Das Erdoelfeld Mittelplate liegt am suedlichen Rand des Nationalparks Schleswig Holsteinisches Wattenmeer, ca. 7000 m westlich der Ortschaft Friedrichskoog. Die gewinnbaren Reserven betragen ca. 30 Millionen t Oel. Bei einer Foerderkapazitaet von 2.500 t/Tag betraegt die Foerderdauer ca. 33 Jahre. Aufgrund der begrenzten Transportkapazitaeten von der Insel, laesst sich durch zusaetzliche Bohrungen von der kuenstlichen Insel Mittelplate keine entscheidende Erhoehung der Foerderkapazitaet erzielen. Ab Sommer 1996 wurde erstmals die Moeglichkeit der Lagerstaettenerschliessung von Land untersucht. Ein im Mai 1997 in Hamburg etabliertes Drilling Team wurde mit der Aufgabe betraut, die Extended Reach Bohrung Dieksand 2 zu planen und abzuteufen. Die Planungsphasen fuer die Extended Reach Bohrung Dieksand 2 wurden aufgezeigt. Die fuer den Erfolg einer Extended Reach Bohrung wichtigen Planungsparameter wurden erlaeutert. Es wurden Wege gezeigt, wie bei diesem Projekt technische und geologische Risiken in der Planung mit beruecksichtigt und nach Beginn der Bohrung weiter bearbeitet werden koennen. (orig.)
Langrock, Roland; Hopcraft, J. Grant C.; Blackwell, Paul G.;
Group dynamic movement is a fundamental aspect of many species' movements. The need to adequately model individuals' interactions with other group members has been recognised, particularly in order to differentiate the role of social forces in individual movement from environmental factors. However...... makes its movement decisions relative to the group centroid. The basic idea is framed within the flexible class of hidden Markov models, extending previous work on modelling animal movement by means of multi-state random walks. While in simulation experiments parameter estimators exhibit some bias...
Updated for 2011, Energy and Movement, is one book in the Britannica Illustrated Science Library Series that covers today's most popular science topics, from digital TV to microchips to touchscreens and beyond. Perennial subjects in earth science, life science, and physical science are all explored in detail. Amazing graphics-more than 1,000 per title-combined with concise summaries help students understand complex subjects. Correlated to the science curriculum in grades 5-9, each title also contains a glossary with full definitions for vocabulary.
Jensen, Søren Kjær; Moser, T.
In: Children and adolescents in movement - perspectives and ideas. The Danish Ministry of Culture, pages 150 - 162. 2003 Short description: the article debunks a lot of the myths surrounding body and learning, and replace them with a vision about another kind of learning. The aim is to reintroduc....... The current focus on the head and lack of attention to the body unifies society to focus on cognitive learning. This has implications for the values created by this system. Learning Lab Denmark aims to examine new ways of reintroducing the body into learning....
Singer, Harvey S
Stereotypic movements are repetitive, rhythmic, fixed, patterned in form, amplitude, and localization, but purposeless (e.g., hand shaking, waving, body rocking, head nodding). They are commonly seen in children; both in normal children (primary stereotypy) and in individuals with additional behavioral or neurological signs and symptoms (secondary stereotypy). They should be differentiated from compulsions (OCD), tics (tic disorders), trichotillomania, skin picking disorder, or the direct physiological effect of a substance. There is increasing evidence to support a neurobiological mechanism. Response to behavioral and pharmacological therapies is variable.
The result of the synergy between four doctoral projects and an advanced MA-level course on Bronze Age Europe, this integrated assemblage of articles represents a variety of different subjects united by a single theme: movement. Ranging from theoretical discussion of the various responses...... to and reactions from the circulation of people, objects and ideas to the transmission of the spiral and the ‚trade’ in crafting expertise, this volume takes a fresh look at old questions. Each article within this monograph represents a different approach to mobility framed within a highly mobile and dynamic...
Christensen, Line Hjorth
commercial and graphic design of various kinds of which British and Foreign Posters offers a particularly rich example. The exhibition attracted commercial, artistic and curatorial forces substantiating the idea of a movement, and approached commercial art from a perspective that raised new awareness towards...... graphic material in urban and museum space alike. To clarify the curatorial approach the analysis draws on a theoretical scheme of ecological semiotics, the concept of counterability and contextualising displays, which I name poster milieux: the 1931 case demonstrates how contemporary commercial art...
The spiking activity in the parietal reach region (PRR) represents the spatial goal of an impending reach when the reach is directed toward or away from a visual object. The local field potentials (LFPs) in this region also represent the reach goal when the reach is directed to a visual object. Thus PRR is a candidate area for reading out a patient's intended reach goals for neural prosthetic applications. For natural behaviors, reach goals are not always based on the location of a visual obj...
Poor communities in remote and inaccessible areas tend to not only be cut off from family planning education and services, but they are also deprived of basic primary health care services. Efforts to bring family planning to such communities and populations should therefore be linked with other services. The author presents three examples of programs to bring effective family planning services to remote communities in Central and South America. Outside of the municipal center in the Tuxtlas region of Mexico, education and health levels are low and people live according to ancient customs. Ten years ago with the help of MEXFAM, the IPPF affiliate in Mexico, two social promoters established themselves in the town of Catemaco to develop a community program of family planning and health care offering education and prevention to improve the quality of people's lives. Through their health brigades taking health services to towns without an established health center, the program has influenced an estimated 100,000 people in 50 villages and towns. The program also has a clinic. In Guatemala, the Family Welfare Association (APROFAM) gave bicycles to 240 volunteer health care workers to facilitate their outreach work in rural areas. APROFAM since 1988 has operated an integrated program to treat intestinal parasites and promote family planning in San Lucas de Toliman, an Indian town close to Lake Atitlan. Providing health care to more than 10,000 people, the volunteer staff has covered the entire department of Solola, reaching each family in the area. Field educators travel on motorcycles through the rural areas of Guatemala coordinating with the health volunteers the distribution of contraceptives at the community level. The Integrated Project's Clinic was founded in 1992 and currently carries out pregnancy and Pap tests, as well as general lab tests. Finally, Puna is an island in the middle of the Gulf of Guayaquil, Ecuador. Women on the island typically have 10
Mehanna, Raja; Jankovic, Joseph
Movement disorders can occur as primary (idiopathic) or genetic disease, as a manifestation of an underlying neurodegenerative disorder, or secondary to a wide range of neurological or systemic diseases. Cerebrovascular diseases represent up to 22% of secondary movement disorders, and involuntary movements develop after 1-4% of strokes. Post-stroke movement disorders can manifest in parkinsonism or a wide range of hyperkinetic movement disorders including chorea, ballism, athetosis, dystonia, tremor, myoclonus, stereotypies, and akathisia. Some of these disorders occur immediately after acute stroke, whereas others can develop later, and yet others represent delayed-onset progressive movement disorders. These movement disorders have been encountered in patients with ischaemic and haemorrhagic strokes, subarachnoid haemorrhage, cerebrovascular malformations, and dural arteriovenous fistula affecting the basal ganglia, their connections, or both.
Hidasi, Zoltan; Salacz, Pal; Csibri, Eva
Movement disorders are common in psychiatry. The movement disorder can either be the symptom of a psychiatric disorder, can share a common aetiological factor with it, or can be the consequence of psychopharmacological therapy. Most common features include tic, stereotypy, compulsion, akathisia, dyskinesias, tremor, hypokinesia and disturbances of posture and gait. We discuss characteristics and clinical importance of these features. Movement disorders are frequently present in mood disorders, anxiety disorders, schizophrenia, catatonia, Tourette-disorder and psychogenic movement disorder, leading to differential-diagnostic and therapeutical difficulties in everyday practice. Movement disorders due to psychopharmacotherapy can be classified as early-onset, late-onset and tardive. Frequent psychiatric comorbidity is found in primary movement disorders, such as Parkinson's disease, Wilson's disease, Huntington's disease, diffuse Lewy-body disorder. Complex neuropsychiatric approach is effective concerning overlapping clinical features and spectrums of disorders in terms of movement disorders and psychiatric diseases.
Geed, Shashwati; McCurdy, Martha L.; van Kan, Peter L. E.
Coordinated reach-to-grasp movements require precise spatiotemporal synchrony between proximal forelimb muscles (shoulder, elbow) that transport the hand toward a target during reach, and distal muscles (wrist, digit) that simultaneously preshape and orient the hand for grasp. The precise mechanisms through which the redundant neuromuscular circuitry coordinates reach with grasp, however, remain unclear. Recently, Geed and Van Kan (2016) demonstrated, using exploratory factor analysis (EFA), that limited numbers of global, template-like transport/preshape- and grasp-related muscle components underlie the complexity and variability of intramuscular electromyograms (EMGs) of up to 21 distal and proximal muscles recorded while monkeys performed reach-to-grasp tasks. Importantly, transport/preshape- and grasp-related muscle components showed invariant spatiotemporal coupling, which provides a potential mechanism for coordinating forelimb muscles during reach-to-grasp movements. In the present study, we tested whether ensemble discharges of forelimb neurons in the cerebellar nucleus interpositus (NI) and its target, the magnocellular red nucleus (RNm), a source of rubrospinal fibers, function as neuronal correlates of the transport/preshape- and grasp-related muscle components we identified. EFA applied to single-unit discharges of populations of NI and RNm neurons recorded while the same monkeys that were used previously performed the same reach-to-grasp tasks, revealed neuronal components in the ensemble discharges of both NI and RNm neuronal populations with characteristics broadly similar to muscle components. Subsets of NI and RNm neuronal components were strongly and significantly crosscorrelated with subsets of muscle components, suggesting that similar functional units of reach-to-grasp behavior are expressed by NI and RNm neuronal populations and forelimb muscles. Importantly, like transport/preshape- and grasp-related muscle components, their NI and RNm
Fang, Yin; Daly, Janis J; Hansley, Jeff; Yao, Wan X; Yang, Qi; Sun, Jiayang; Hvorat, Ken; Pundik, Svetlana; Yue, Guang H
Enhanced activation in the non-lesion hemisphere in stroke patients was widely observed during movement of the affected upper limb, but its functional role related to motor planning and execution is still unknown.This study was to characterize the activation in the non-lesion hemisphere during movement planning and execution by localizing sources of high-density electroencephalography (EEG) signal and estimating the source strength (current density [A/m]).Ten individuals with chronic stroke and shoulder/elbow coordination deficits and 5 healthy controls participated in the study.EEG (64 channels) was recorded from scalp electrodes while the subjects performed a reach task involving shoulder flexion and elbow extension of the affected (patients) or dominant (controls) upper extremity. Sources of the EEG were obtained and analyzed at 17 time points across movement preparation and execution phases. A 3-layer boundary element model was overlaid and used to identify the brain activation sources. A distributed current density model, low-resolution electromagnetic tomography (LORETA) L1 norm method, was applied to the data pre-processed by independent component analysis.Subjects with stroke had stronger source strength in the sensorimotor cortices during the movement compared with the controls. Their contralesional/lesional activation ratio (CTLR) for the primary motor cortices was significantly higher than that of the controls during the movement-planning phase, but not during the execution phase. The CTLR was higher in planning than in the execution phase in the stroke group.Excessive contralesional motor cortical activation appears to be more related to movement preparation rather than execution in chronic stroke.
The aim of this article is to review movement disorders in children. They are common but have etiology and phenomenology different than in adults. Tics are the most common phenomena although in most instances they are mild and have a favorable long-term prognosis. Dystonia is the second most common phenomena but when present it is usually genetic or idiopathic and causes meaningful disability. Sydenham's chorea is the most common cause of chorea in children worldwide. Systemic lupus erythematosus is a much rarer cause of chorea but it is always to be ruled out given the lack of a specific diagnostic marker for Sydenham's chorea. Tremor, usually caused by drugs or essential tremor, is regarded as rather uncommon in children. Arguably, most pediatric patients with tremor do not seek medical attention because of the lack of disability. Stereotypies are relatively uncommon but their recognition is clinically relevant since they are usually associated with severe conditions such as autism and Rett syndrome. Parkinsonism is quite rare in children and either results from encephalitis or is a side effect of medications. Wilson's disease must be ruled out in all children with movement disorders.
Lynch, A; Lee, H M; Bhat, A; Galloway, J C
Adult hand preference emerges from complex developmental changes in arm and hand use during childhood. Recent reports have highlighted the importance of understanding arm and hand use during the first year of life including the period before reach onset. This longitudinal study tested the hypothesis that significant right-left differences exist in pre-reaching arm movements. We examined right and left hand kinematics from 13 healthy infants during trials with and without a toy present from 8 weeks of age through the week of reach onset. Significant right-left differences were found, however there was no clear pattern within a condition or across conditions. Without a toy present, the right hand moved faster, yet ended further from midline, and displayed more movements during the Late phase compared to other phases. With a toy present, the right hand moved longer lengths, yet ended movements further away from the toy. When left and right hand kinematics were combined, previous findings of right hand kinematics alone were supported. Although infants begin adapting their pre-reaching kinematics many weeks before reach onset, we did not find evidence of a systematic right--left difference before reach onset in movements with or without a toy present. Our results, coupled with other reports, suggest hand asymmetries begin to emerge over the year following reach onset amid developmental changes both within the infant, and the physical and social environment.
van Balen, Lieke C; Dijkstra, Linze Jaap; Hadders-Algra, Mijna
Knowledge on the development of postural adjustments during infancy, in particular on the development of postural muscle coordination, is limited. This study aimed at the evaluation of the development of postural control during reaching in a supported sitting condition. Eleven typically developing infants participated in the study and were assessed at the ages of 4, 6, 10 and 18 months. We elicited reaching movements by presenting small toys at an arm's length distance, whilst activity of multiple arm, neck and trunk muscles was recorded using surface EMG. A model-based computer algorithm was used to detect the onset of phasic muscle activity. The results indicated that postural muscle activity during reaching whilst sitting supported is highly variable. Direction-specific postural activity was inconsistently present from early age onwards and increased between 10 and 18 months without reaching a 100 % consistency. The dominant pattern of activation at all ages was the 'complete pattern', in which all direction-specific muscles were recruited. At 4 months, a slight preference for top-down recruitment existed, which was gradually replaced by a preference for bottom-up recruitment. We conclude that postural control during the ecological task of reaching during supported sitting between 4 and 18 months of age is primarily characterized by variation. Already from 4 months onwards, infants are-within the variation-sometimes able to select muscle recruitment strategies that are optimal to the task at hand.
Full Text Available This study aimed to investigate whether the cognition of spatial distance in reaching movements was decreased in patients with Parkinson’s disease (PD and whether this cognition was associated with various symptoms of PD. Estimated and actual maximal reaching distances were measured in three directions in PD patients and healthy elderly volunteers. Differences between estimated and actual measurements were compared within each group. In the PD patients, the associations between “error in cognition” of reaching distance and “clinical findings” were also examined. The results showed that no differences were observed in any values regardless of dominance of hand and severity of symptoms. The differences between the estimated and actual measurements were negatively deviated in the PD patients, indicating that they tended to underestimate reaching distance. “Error in cognition” of reaching distance correlated with the items of posture in the motor section of the Unified Parkinson’s Disease Rating Scale. This suggests that, in PD patients, postural deviation and postural instability might affect the cognition of the distance from a target object.
Kuhtz-Buschbeck, J P; Stolze, H; Jöhnk, K; Boczek-Funcke, A; Illert, M
To evaluate the normal development of functional hand motor skill, the kinematics of prehension movements were analyzed in 54 healthy children (age 4-12 years). The subjects repeatedly reached out for cylindrical target objects and grasped them with a precision grip of their dominant hand. The trajectory of the reaching hand and the finger aperture were monitored by optoelectronic motion analysis. To obtain comparable conditions for the different age groups, the experimental setup was scaled according to the individual body proportions of each subject. Within the investigated age range, neither the movement duration nor the normalized (according to body proportions) peak spatial velocity of the reaching hand changed significantly. However, the hand trajectory straightened and the coordination between hand transport and grip formation improved, resulting in smooth and stereotyped kinematic profiles at the age of 12 years. The younger children opened their grip relatively wider than the older ones, thus grasping with a higher safety margin. The dependence on visual control of the movement declined during motor development. Only the oldest children were able to scale the grip aperture adequately, according to various sizes of the target objects, when visual control of the movement was lacking. The results suggest that the development of prehensile skills during childhood lasts until the end of the first decade of life. This functional maturation is discussed in relation to the development of neuronal pathways.
Full Text Available The basal ganglia are known to play a crucial role in movement execution, but their importance for motor skill learning remains unclear. Obstacles to our understanding include the lack of a universally accepted definition of motor skill learning (definition confound, and difficulties in distinguishing learning deficits from execution impairments (performance confound. We studied how healthy subjects and subjects with a basal ganglia disorder learn fast accurate reaching movements, and we addressed the definition and performance confounds by: 1 focusing on an operationally defined core element of motor skill learning (speed-accuracy learning, and 2 using normal variation in initial performance to separate movement execution impairment from motor learning abnormalities. We measured motor skill learning learning as performance improvement in a reaching task with a speed-accuracy trade-off. We compared the performance of subjects with Huntington’s disease (HD, a neurodegenerative basal ganglia disorder, to that of premanifest carriers of the HD mutation and of control subjects. The initial movements of HD subjects were less skilled (slower and/or less accurate than those of control subjects. To factor out these differences in initial execution, we modeled the relationship between learning and baseline performance in control subjects. Subjects with HD exhibited a clear learning impairment that was not explained by differences in initial performance. These results support a role for the basal ganglia in both movement execution and motor skill learning.
Over the last 50 years, neurophysiologists have described many neural circuits that transform sensory input into motor commands, while biomechanicians and behavioral biologists have described many patterns of animal movement that occur in response to sensory input. Attempts to link these two have been frustrated by our technical inability to record from the necessary neurons in a freely behaving animal. As a result, we don't know how these neural circuits function in the closed loop context of free behavior, where the sensory and motor context changes on a millisecond time-scale. To address this problem, we have developed a software package, AnimatLab (www.AnimatLab.com), that enables users to reconstruct an animal's body and its relevant neural circuits, to link them at the sensory and motor ends, and through simulation, to test their ability to reproduce appropriate patterns of the animal's movements in a simulated Newtonian world. A Windows-based program, AnimatLab consists of a neural editor, a body editor, a world editor, stimulus and recording facilities, neural and physics engines, and an interactive 3-D graphical display. We have used AnimatLab to study three patterns of behavior: the grasshopper jump, crayfish escape, and crayfish leg movements used in postural control, walking, reaching and grasping. In each instance, the simulation helped identify constraints on both nervous function and biomechanical performance that have provided the basis for new experiments. Colleagues elsewhere have begun to use AnimatLab to study control of paw movements in cats and postural control in humans. We have also used AnimatLab simulations to guide the development of an autonomous hexapod robot in which the neural control circuitry is downloaded to the robot from the test computer.
Mirror movements are simultaneous, involuntary, identical movements occurring during contralateral voluntary movements. These movements are considered as soft neurologic signs seen uncommonly in clinical practice. The mirror movements are described in various neurological disorders which include parkinsonism, cranio veretebral junction anamolies, and hemiplegic cerebral palsy. These movements are intriguing and can pose significant disability. However, no such observation regarding mirror mov...
This contribution concerns itself with the design and realisation of architectures that operate with material dynamics. It presents this concern as a counter to the consideration of movement in architecture as something conceptualised from the position of the observer. The contribution draws upon...... research from the Centre for Information Technology and Architecture (CITA) which has recently focused upon the investigation of materially active systems ranging from textile logics at architectural scale to bending active structures in both natural and synthetic fibre-based composites....... These investigations have necessitated the development of synergetic relations between new conceptualisations, new methods of designing, new representational tools, and new material systems. This essay examines these issues through two inter-related research projects developed at CITA as part of a broader inquiry...
Staude, G; Dengler, R; Wolf, W
Initiation of rapid discrete flexion movements is significantly altered when a secondary rhythmic movement is performed simultaneously with the same limb; the onset of a stimulus-evoked discrete movement tends to occur time-locked to the oscillation: i.e., the rhythmic movement entrains the discrete response. This nonlinear interaction may reflect a specific principle of coordination of motor tasks which are simultaneously executed with the same effector. This part II of a tripartite research report on such single-muscle multiple-task coordination investigates the contribution of the dynamic properties of the muscle and its reflex circuitry to phase entrainment. Assuming a simple threshold-linear relationship between the control signals generated by the central nervous system and the observable kinematic and electromyographic signals, a secondary rhythmic movement will cause an additional phase-dependent delay between the central "go" command and the first observable change in actual kinematics of the compound movement. Several indicators for such threshold-linear interaction are derived and tested on real data obtained in psychophysical experiments. Four healthy subjects performed rapid lateral abductions of the index finger in response to a visual "go" signal. During a portion of the experiments, subjects produced additional low-amplitude oscillatory movements before stimulus presentation with either the same finger (one-handed task), or with the index finger of the other hand (two-handed task). Results showed phase entrainment and modulation of reaction times when the cyclic and the discrete movements were simultaneously executed by the same finger. But there was no entrainment in the bimanual execution of the tasks. The model was capable of reproducing the observed effects. It is concluded that coordination of voluntary movements which are concurrently performed by the same effector involves specific discontinuous operations, which represents an essential part
Butler, Erin E; Ladd, Amy L; Lamont, Lauren E; Rose, Jessica
The objective of this study was to characterize normal temporal-spatial patterns during the Reach & Grasp Cycle and to identify upper limb motor deficits in children with cerebral palsy (CP). The Reach & Grasp Cycle encompasses six sequential tasks: reach, grasp cylinder, transport to self (T(1)), transport back to table (T(2)), release cylinder, and return to initial position. Three-dimensional motion data were recorded from 25 typically developing children (11 males, 14 females; ages 5-18 years) and 12 children with hemiplegic CP (2 males, 10 females; ages 5-17 years). Within-day and between-day coefficients of variation for the control group ranged from 0 to 0.19, indicating good repeatability of all parameters. The mean duration of the Cycle for children with CP was nearly twice as long as controls, 9.5±4.3s versus 5.1±1.2s (U=37.0, P=.002), partly due to prolonged grasp and release durations. Peak hand velocity occurred at approximately 40% of each phase and was greater during the transport (T(1), T(2)) than non-transport phases (reach, return) in controls (Pchildren. Children with CP demonstrated an increased index of curvature during reach (U=46.0, P=.0074) and an increased total number of movement units (U=16.5, Pmovements. Total duration of the Reach & Grasp Cycle (rho=.957, Pmovement units (rho=.907, Pchildren with CP and controls reflect utility of the Reach & Grasp Cycle for quantitative evaluation of upper limb motor deficits.
Schaefer, S Y; Hengge, C R
Point-to-point reaching has been widely used to study upper extremity motor control. We have been developing a naturalistic reaching task that adds tool manipulation and object transport to this established paradigm. The purpose of this study was to determine the concurrent validity of a naturalistic reaching task in a sample of healthy adults. This task was compared to the criterion measure of standard point-to-point reaching. Twenty-eight adults performed unconstrained out-and-back movements in three different directions relative to constant start location along midline using their nondominant arm. In the naturalistic task, participants manipulated a tool to transport objects sequentially between physical targets anchored to the planar workspace. In the standard task, participants moved a digital cursor sequentially between virtual targets, veridical to the planar workspace. In both tasks, the primary measure of performance was trial time, which indicated the time to complete 15 reaches (five cycles of three reaches/target). Two other comparator tasks were also designed to test concurrent validity when components of the naturalistic task were added to the standard task. Spearman's rank correlation coefficients indicated minimal relationship between the naturalistic and standard tasks due to differences in progressive task difficulty. Accounting for this yielded a moderate linear relationship, indicating concurrent validity. The comparator tasks were also related to both the standard and naturalistic task. Thus, the principles of motor control and learning that have been established by the wealth of point-to-point reaching studies can still be applied to the naturalistic task to a certain extent.
Johnson, P B; Ferraina, S; Bianchi, L; Caminiti, R
The functional and structural properties of the dorsolateral frontal lobe and posterior parietal proximal arm representations were studied in macaque monkeys. Physiological mapping of primary motor (MI), dorsal premotor (PMd), and posterior parietal (area 5) cortices was performed in behaving monkeys trained in an instructed-delay reaching task. The parietofrontal corticocortical connectivities of these same areas were subsequently examined anatomically by means of retrograde tracing techniques. Signal-, set-, movement-, and position-related directional neuronal activities were distributed nonuniformly within the task-related areas in both frontal and parietal cortices. Within the frontal lobe, moving caudally from PMd to the MI, the activity that signals for the visuo-spatial events leading to target localization decreased, while the activity more directly linked to movement generation increased. Physiological recordings in the superior parietal lobule revealed a gradient-like distribution of functional properties similar to that observed in the frontal lobe. Signal- and set-related activities were encountered more frequently in the intermediate and ventral part of the medial bank of the intraparietal sulcus (IPS), in area MIP. Movement-and position-related activities were distributed more uniformly within the superior parietal lobule (SPL), in both dorsal area 5 and in MIP. Frontal and parietal regions sharing similar functional properties were preferentially connected through their association pathways. As a result of this study, area MIP, and possibly areas MDP and 7m as well, emerge as the parietal nodes by which visual information may be relayed to the frontal lobe arm region. These parietal and frontal areas, along with their association connections, represent a potential cortical network for visual reaching. The architecture of this network is ideal for coding reaching as the result of a combination between visual and somatic information.
Psychogenic movement disorders (PMDs) are common, but their physiology is largely unknown. In most situations, the movement is involuntary, but in a minority, when the disorder is malingering or factitious, the patient is lying and the movement is voluntary. Physiologically, we cannot tell the difference between voluntary and involuntary. The Bereitschaftspotential (BP) is indicative of certain brain mechanisms for generating movement, and is seen with ordinarily voluntary movements, but by itself does not indicate that a movement is voluntary. There are good clinical neurophysiological methods available to determine whether myoclonus or tremor is a PMD. For example, psychogenic myoclonus generally has a BP, and psychogenic stimulus-sensitive myoclonus has a variable latency with times similar to normal reaction times. Psychogenic tremor will have variable frequency over time, be synchronous in the two arms, and might well be entrained with voluntary rhythmic movements. These facts suggest that PMDs share voluntary mechanisms for movement production. There are no definitive tests to differentiate psychogenic dystonia from organic dystonia, although one has been recently reported. Similar physiological abnormalities are seen in both groups. The question arises as to how a movement can be produced with voluntary mechanisms, but not be considered voluntary.
Lackner, James R; DiZio, Paul
Subjects exposed to constant velocity rotation in a large fully-enclosed room that rotates initially make large reaching errors in pointing to targets. The paths and endpoints of their reaches are deviated in the direction of the transient lateral Coriolis forces generated by the forward velocity of their reaches. With additional reaches, subjects soon reach in straighter paths and become more accurate at landing on target even in the absence of visual feedback about their movements. Two factors contribute to this adaptation: first, muscle spindle and golgi tendon organ feedback interpreted in relation to efferent commands provide information about movement trajectory, and second, somatosensory stimulation of the fingertip at the completion of a reach provides information about the location of the fingertip relative to the torso.
U.S. Geological Survey, Department of the Interior — U.S. Environmental Protection Agency's River Reach File 1 (RF1)to ensure the hydrologic integrity of the digital reach traces and to quantify the mean water time of...
Minetti, Andrea; Hurtado, Northan; Grais, Rebecca F; Ferrari, Matthew
Current mass vaccination campaigns in measles outbreak response are nonselective with respect to the immune status of individuals. However, the heterogeneity in immunity, due to previous vaccination coverage or infection, may lead to potential bias of such campaigns toward those with previous high access to vaccination and may result in a lower-than-expected effective impact. During the 2010 measles outbreak in Malawi, only 3 of the 8 districts where vaccination occurred achieved a measureable effective campaign impact (i.e., a reduction in measles cases in the targeted age groups greater than that observed in nonvaccinated districts). Simulation models suggest that selective campaigns targeting hard-to-reach individuals are of greater benefit, particularly in highly vaccinated populations, even for low target coverage and with late implementation. However, the choice between targeted and nonselective campaigns should be context specific, achieving a reasonable balance of feasibility, cost, and expected impact. In addition, it is critical to develop operational strategies to identify and target hard-to-reach individuals.
Fuchs, Melani Alexander
Montessori's first premise is that movement and cognition are closely entwined, and movement can enhance thinking and learning (Lillard, 2005). Children must move, and practice moving, to develop strength, balance, and the stability needed to fully participate in the rigors of daily life. It is imperative for young children's motor…
Costa e Silva, E.; Araújo, J. P.; Machado, D.; Costa, M. F.; Erlhagen, W.; Bicho, E.
In previous work we have presented a model for generating human-like arm and hand movements on an anthropomorphic robot involved in human-robot collaboration tasks. This model was inspired by the Posture-Based Motion-Planning Model of human movements. Numerical results and simulations for reach-to-grasp movements with two different grip types have been presented previously. In this paper we extend our model in order to address the generation of more complex movement sequences which are challenged by scenarios cluttered with obstacles. The numerical results were obtained using the IPOPT solver, which was integrated in our MATLAB simulator of an anthropomorphic robot.
Santello, Marco; Lang, Catherine E
The intact nervous system has an exquisite ability to modulate the activity of multiple muscles acting at one or more joints to produce an enormous range of actions. Seemingly simple tasks, such as reaching for an object or walking, in fact rely on very complex spatial and temporal patterns of muscle activations. Neurological disorders such as stroke and focal dystonia affect the ability to coordinate multi-joint movements. This article reviews the state of the art of research of muscle synergies in the intact and damaged nervous system, their implications for recovery and rehabilitation, and proposes avenues for research aimed at restoring the nervous system's ability to control movement.
Stich, Daniel S.; Kinnison, Michael T.; Kocik, John F.; Zydlewski, Joseph
Timing of ocean entry is critical for marine survival of both hatchery and wild Atlantic salmon (Salmo salar) smolts. Management practices and barriers to migration such as dams may constrain timing of smolt migrations resulting in suboptimal performance at saltwater entry. We modeled influences of stocking location, smolt development, and environmental conditions on (i) initiation of migration by hatchery-reared smolts and (ii) movement rate of hatchery- and wild-reared Atlantic salmon smolts in the Penobscot River, Maine, USA, from 2005 through 2014 using acoustic telemetry data. We also compared movement rates in free-flowing reaches with rates in reaches with hydropower dams and head ponds. We compared movement rates before and after (1) removal of two mainstem dams and (2) construction of new powerhouses. Initiation of movement by hatchery fish was influenced by smolt development, stocking location, and environmental conditions. Smolts with the greatest gill Na+, K+-ATPase (NKA) activity initiated migration 24 h sooner than fish with the lowest gill NKA activity. Fish with the greatest cumulative thermal experience initiated migration 5 days earlier than those with lowest cumulative thermal experience. Smolts released furthest from the ocean initiated migration earlier than those released downstream, but movement rate increased by fivefold closer to the ocean, indicating behavioral trade-offs between initiation and movement rate. Dams had a strong effect on movement rate. Movement rate increased from 2.8 to 5.4 km·h−1 in reaches where dams were removed, but decreased from 2.1 to 0.1 km·h−1 in reaches where new powerhouses were constructed. Movement rate varied throughout the migratory period and was inversely related to temperature. Fish moved slower at extreme high or low discharge. Responses in fish movement rates to dam removal indicate the potential scope of recovery for these activities.
Full Text Available A variety of nervous system components such as medulla, pons, midbrain, cerebellum, basal ganglia, parietal, frontal and occipital lobes have role in Eye Movement Desensitization and Reprocessing (EMDR processes. The eye movement is done simultaneously for attracting client's attention to an external stimulus while concentrating on a certain internal subject. Eye movement guided by therapist is the most common attention stimulus. The role of eye movement has been documented previously in relation with cognitive processing mechanisms. A series of systemic experiments have shown that the eyes’ spontaneous movement is associated with emotional and cognitive changes and results in decreased excitement, flexibility in attention, memory processing, and enhanced semantic recalling. Eye movement also decreases the memory's image clarity and the accompanying excitement. By using EMDR, we can reach some parts of memory which were inaccessible before and also emotionally intolerable. Various researches emphasize on the effectiveness of EMDR in treating and curing phobias, pains, and dependent personality disorders. Consequently, due to the involvement of multiple neural system components, this palliative method of treatment can also help to rehabilitate the neuro-cognitive system.
Hwang, Eun Jung; Andersen, Richard A
The spiking activity in the parietal reach region (PRR) represents the spatial goal of an impending reach when the reach is directed toward or away from a visual object. The local field potentials (LFPs) in this region also represent the reach goal when the reach is directed to a visual object. Thus PRR is a candidate area for reading out a patient's intended reach goals for neural prosthetic applications. For natural behaviors, reach goals are not always based on the location of a visual object, e.g., playing the piano following sheet music or moving following verbal directions. So far it has not been directly tested whether and how PRR represents reach goals in such cognitive, nonlocational conditions, and knowing the encoding properties in various task conditions would help in designing a reach goal decoder for prosthetic applications. To address this issue, we examined the macaque PRR under two reach conditions: reach goal determined by the stimulus location (direct) or shape (symbolic). For the same goal, the spiking activity near reach onset was indistinguishable between the two tasks, and thus a reach goal decoder trained with spiking activity in one task performed perfectly in the other. In contrast, the LFP activity at 20-40 Hz showed small but significantly enhanced reach goal tuning in the symbolic task, but its spatial preference remained the same. Consequently, a decoder trained with LFP activity performed worse in the other task than in the same task. These results suggest that LFP decoders in PRR should take into account the task context (e.g., locational vs. nonlocational) to be accurate, while spike decoders can robustly provide reach goal information regardless of the task context in various prosthetic applications.
The theosophical movement has had a significant influence on the esoteric milieu in Denmark during the 20th Century. In this paper the inspiration on other Groups in Denmark is explored.......The theosophical movement has had a significant influence on the esoteric milieu in Denmark during the 20th Century. In this paper the inspiration on other Groups in Denmark is explored....
Gaalen, J. van; Giunti, P.; Warrenburg, B.P.C. van de
Autosomal dominant spinocerebellar ataxias (SCAs) can present with a large variety of noncerebellar symptoms, including movement disorders. In fact, movement disorders are frequent in many of the various SCA subtypes, and they can be the presenting, dominant, or even isolated disease feature. When c
Toftum, Jørn; Melikov, Arsen Krikor; Tynel, A.;
Human preference for air movement was studied at slightly cool, neutral, and slightly warm overall thermal sensations and at temperatures ranging from 18 deg.C to 28 deg.C. Air movement preference depended on both thermal sensation and temperature, but large inter-individual differences existed...
A.M. van Alphen (Adriaan)
textabstractThis thesis will address the generation of compensatory eye movements in naturally mutated or genetically modified mice. The reason for generating compensatory eye movements is solely related to the requirements for good vision. In a subject moving through its environment the projection
Drawing a distinction between systemic and functional explanations of movement in general, I shall argue that the Chomskyan view of movement in language is originally functional. With the advent of the Minimimalist Program, however, it has become systemic, but no argument for this change has been...
Møllenbach, Emilie; Hansen, John Paulin; Lillholm, Martin
Gaze as a sole input modality must support complex navigation and selection tasks. Gaze interaction combines specific eye movements and graphic display objects (GDOs). This paper suggests a unifying taxonomy of gaze interaction principles. The taxonomy deals with three types of eye movements: fix...
Air movement - good or bad? The question can only be answered by those who are exposed when they are exposed. Human perception of air movement depends on environmental factors including air velocity, air velocity fluctuations, air temperature, and personal factors such as overall thermal sensation...... and activity level. Even for the same individual, sensitivity to air movement may change from day to day as a result of e.g. different levels of fatigue. Based on existing literature, the current paper summarizes factors influencing the human perception of air movement and attempts to specify in general terms...... influences the subjective perception of air movement. With occupants feeling warmer than neutral, at temperatures above 23oC or at raised activity levels, humans generally do not feel draught at air velocities typical for indoor environments (up to around 0.4 m/s). In the higher temperature range, very high...
Wagman, Jeffrey B; Day, Brian M
Successfully performing a given behavior requires flexibility in both perception and behavior. In particular, doing so requires perceiving whether that behavior is possible across the variety of contexts in which it might be performed. Three experiments investigated how (changes in) context (ie point of observation and intended reaching task) influenced perception of maximum reaching height. The results of experiment 1 showed that perceived maximum reaching height more closely reflected actual reaching ability when perceivers occupied a point of observation that was compatible with that required for the reaching task. The results of experiments 2 and 3 showed that practice perceiving maximum reaching height from a given point of observation improved perception of maximum reaching height from a different point of observation, regardless of whether such practice occurred at a compatible or incompatible point of observation. In general, such findings show bounded flexibility in perception of affordances and are thus consistent with a description of perceptual systems as smart perceptual devices.
Cañal-Bruland, Rouwen; Williams, A Mark
It is not clear whether the critical features used to discriminate movements are identical to those involved in predicting the same movement's effects and consequently, whether the mechanisms underlying recognition and anticipation differ. We examined whether people rely on different kinematic information when required to recognize differences in the movement pattern in comparison to when they have to anticipate the outcome of these same movements. Naïve participants were presented with paired presentations of point-light animated tennis shots that ended at racket-ball contact. We instructed them either to judge whether the movements observed were the same or different or to predict shot direction (left vs. right). In addition, we locally manipulated the kinematics of point-light figures in an effort to identify the critical features used when making recognition and anticipation judgments. It appears that observers rely on different sources of information when required to recognize movement differences compared to when they need to anticipate the outcome of the same observed movements. Findings are discussed with reference to recent ideas focusing on the role of perceptual and motor resonance in perceptual judgments.
Paolucci, Teresa; Zangrando, Federico; Piccinini, Giulia; Sciarra, Federico; Pallotta, Rocco; Mannocci, Alice; la Torre, Giuseppe; Bini, Fabiano; Marinozzi, Franco; Gumina, Stefano; Padua, Luca; Saraceni, Vincenzo Maria
Background. The position sense of the shoulder joint is important during reaching. Objective. To examine the existence of additional competence of the shoulder with regard to the ability to measure extracorporeal space, through a novel approach, using the shoulder proprioceptive rehabilitation tool (SPRT), during reaching. Design. Observational case-control study. Methods. We examined 50 subjects: 25 healthy and 25 with impingement syndrome with a mean age [years] of 64.52 +/- 6.98 and 68.36 +/- 6.54, respectively. Two parameters were evaluated using the SPRT: the integration of visual information and the proprioceptive afferents of the shoulder (Test 1) and the discriminative proprioceptive capacity of the shoulder, with the subject blindfolded (Test 2). These tasks assessed the spatial error (in centimeters) by the shoulder joint in reaching movements on the sagittal plane. Results. The shoulder had proprioceptive features that allowed it to memorize a reaching position and reproduce it (error of 1.22 cm to 1.55 cm in healthy subjects). This ability was lower in the impingement group, with a statistically significant difference compared to the healthy group (p shoulder has specific expertise in the measurement of the extracorporeal space during reaching movements that gradually decreases in impingement syndrome.
Chen, Hao-Ling; Yeh, Chun-Fu; Howe, Tsu-Hsin
The purpose of the present study was to investigate the dynamic postural control of children with Down syndrome (DS). Specifically, we compared postural control and goal-directed reaching performance between children with DS and typically developing children during standing reach. Standing reach performance was analyzed in three main phases using the kinematic and kinetic data collected from a force plate and a motion capture system. Fourteen children with DS, age and gender matched with fourteen typically developing children, were recruited for this study. The results showed that the demand of the standing reach task affected both dynamic postural control and reaching performance in children with DS, especially in the condition of beyond arm's length reaching. More postural adjustment strategies were recruited when reaching distance was beyond arm's length. Children with DS tended to use inefficient and conservative strategies for postural stability and reaching. That is, children with DS perform standing reach with increased reaction and execution time and decreased amplitudes of center of pressure displacements. Standing reach resembled functional balance that is required in daily activities. It is suggested to be considered as a part of strength and balance training program with graded task difficulty.
Roatta, Silvestro; Rolando, M; Notaro, V; Testa, M; Bassi, F; Passatore, M
Mandibular motor function is well known to be impaired in the presence of temporomandibular disorders. However, while a vast literature is available concerning accuracy of motor control in limbs, quantitative and objective assessment of mandibular motor control has been seldom performed, also because of the lack of adequate investigative tools. Aim of this work is to present a technique for reliable evaluation of the motor performance of the mandible based on a kinesiography-monitored reach-and-hold task. Nineteen healthy subjects were engaged in a task in which they had to drive a cursor on a screen by corresponding movements of the mandible in the frontal plane and reach 30 random targets sequentially displayed on the screen. The whole task was repeated three times per session in two different days. The individual performance was assessed by different indices evaluating precision and steadiness of target matching. The performance progressively improved in the three trials of the first session, further improved and stabilised in the second session, with an average positioning error of 0·59 ± 038 mm and was slightly correlated with the horizontal dimension of the mandible border movement (r = 0·55). Intraclass correlation coefficient ranged between 0·76 and 0·94 for the different indices indicating good repeatability. The kinesiographic technique allowed for objective and reliable assessment of the voluntary control of the mandible position. Its potential applications include support to the characterisation of temporomandibular disorders and to motor training and progress monitoring in rehabilitation treatments.
Risager, Bjarke Skærlund
Inspired by the Occupy movement, the Egyptian revolutionaries and other of the 2011 social movements, this paper investigates the relationship between social movement and place. Drawing on first-hand accounts from these movements, I argue that the relationship between movement and place is dialec...
National Oceanic and Atmospheric Administration, Department of Commerce — This project is to determine horizontal and vertical movement patterns of two jellyfish species in Hood Canal, in relation to environmental variables. It is being...
Salmond, Layne H; Davidson, Andrew D; Charles, Steven K
Smoothness is a hallmark of healthy movement. Past research indicates that smoothness may be a side product of a control strategy that minimizes error. However, this is not the only reason for smooth movements. Our musculoskeletal system itself contributes to movement smoothness: the mechanical impedance (inertia, damping, and stiffness) of our limbs and joints resists sudden change, resulting in a natural smoothing effect. How the biomechanics and neural control interact to result in an observed level of smoothness is not clear. The purpose of this study is to 1) characterize the smoothness of wrist rotations, 2) compare it with the smoothness of planar shoulder-elbow (reaching) movements, and 3) determine the cause of observed differences in smoothness. Ten healthy subjects performed wrist and reaching movements involving different targets, directions, and speeds. We found wrist movements to be significantly less smooth than reaching movements and to vary in smoothness with movement direction. To identify the causes underlying these observations, we tested a number of hypotheses involving differences in bandwidth, signal-dependent noise, speed, impedance anisotropy, and movement duration. Our simulations revealed that proximal-distal differences in smoothness reflect proximal-distal differences in biomechanics: the greater impedance of the shoulder-elbow filters neural noise more than the wrist. In contrast, differences in signal-dependent noise and speed were not sufficiently large to recreate the observed differences in smoothness. We also found that the variation in wrist movement smoothness with direction appear to be caused by, or at least correlated with, differences in movement duration, not impedance anisotropy.NEW & NOTEWORTHY This article presents the first thorough characterization of the smoothness of wrist rotations (flexion-extension and radial-ulnar deviation) and comparison with the smoothness of reaching (shoulder-elbow) movements. We found wrist
Full Text Available In this review, we introduced our three studies that focused on facial movements. In the first study, we examined the temporal characteristics of neural responses elicited by viewing mouth movements, and assessed differences between the responses to mouth opening and closing movements and an averting eyes condition. Our results showed that the occipitotemporal area, the human MT/V5 homologue, was active in the perception of both mouth and eye motions. Viewing mouth and eye movements did not elicit significantly different activity in the occipitotemporal area, which indicated that perception of the movement of facial parts may be processed in the same manner, and this is different from motion in general. In the second study, we investigated whether early activity in the occipitotemporal region evoked by eye movements was influenced by a face contour and/or features such as the mouth. Our results revealed specific information processing for eye movements in the occipitotemporal region, and this activity was significantly influenced by whether movements appeared with the facial contour and/or features, in other words, whether the eyes moved, even if the movement itself was the same. In the third study, we examined the effects of inverting the facial contour (hair and chin and features (eyes, nose, and mouth on processing for static and dynamic face perception. Our results showed the following: (1 In static face perception, activity in the right fusiform area was affected more by the inversion of features while that in the left fusiform area was affected more by a disruption in the spatial relationship between the contour and features, and (2 In dynamic face perception, activity in the right occipitotemporal area was affected by the inversion of the facial contour.
In nature, any movement of the object is a curve, in the process of motion by at least two forces, the two opposite direction of force moment, or a force component and another force in the opposite direction, and the effect on the same object motion curve, the two a force is the attraction and repulsion. Analysis one: when gravity is greater than or equal to the repulsive, objects can be attached to another object, as are attached to rotate together (at this time , the attraction force and repulsion force may in the opposite direction) may also be an object around another object. Or finally attached to another object (for example, velocity smaller projectile motion). Analysis two: when the repulsive force greater than gravity, objects from the attached objects do eccentric exercise. The final result is: the object which is attached around a circular motion, repulsion and attraction to reach dynamic equilibrium. Or completely escape from the attached objects. Analysis three: when people stand on the earth, the movement is a circular motion whose repulsion greater than the gravitational ,at this time, the component of gravity and repulsion force in the opposite direction, the size of approximately equal.
Renato P. Munhoz
Full Text Available Movement disorders (MD encompass acute and chronic diseases characterized by involuntary movements and/or loss of control or efficiency in voluntary movements. In this review, we covered situations in which the main manifestations are MDs that pose significant risks for acute morbidity and mortality. The authors examine literature data on the most relevant MD emergencies, including those related to Parkinson's disease, acute drug reactions (acute dystonia, neuroleptic malignant syndrome, serotonergic syndrome and malignant hyperthermia, acute exacerbation of chronic MD (status dystonicus, hemiballism and stiff-person syndrome, highlighting clinical presentation, demographics, diagnosis and management.
Poewe, Werner; Djamshidian-Tehrani, Atbin
Movement disorders, classically involving dysfunction of the basal ganglia commonly occur in neurodegenerative and structural brain disorders. At times, however, movement disorders can be the initial manifestation of a systemic disease. In this article we discuss the most common movement disorders which may present in infectious, autoimmune, paraneoplastic, metabolic and endocrine diseases. Management often has to be multidisciplinary involving primary care physicians, neurologists, allied health professionals including nurses, occupational therapists and less frequently neurosurgeons. Recognizing and treating the underlying systemic disease is important in order to improve the neurological symptoms.
Norman, J.R.; Hagler, M.M.; Freeman, Mary C.; Freeman, B.J.
While it is widely acknowledged that culverted road-stream crossings may impede fish passage, effects of culverts on movement of nongame and small-bodied fishes have not been extensively studied and studies generally have not accounted for spatial variation in capture probabilities. We estimated probabilities for upstream and downstream movement of small (30-120 mm standard length) benthic and water column fishes across stream reaches with and without culverts at four road-stream crossings over a 4-6-week period. Movement and reach-specific capture probabilities were estimated using multistate capture-recapture models. Although none of the culverts were complete barriers to passage, only a bottomless-box culvert appeared to permit unrestricted upstream and downstream movements by benthic fishes based on model estimates of movement probabilities. At two box culverts that were perched above the water surface at base flow, observed movements were limited to water column fishes and to intervals when runoff from storm events raised water levels above the perched level. Only a single fish was observed to move through a partially embedded pipe culvert. Estimates for probabilities of movement over distances equal to at least the length of one culvert were low (e.g., generally ???0.03, estimated for 1-2-week intervals) and had wide 95% confidence intervals as a consequence of few observed movements to nonadjacent reaches. Estimates of capture probabilities varied among reaches by a factor of 2 to over 10, illustrating the importance of accounting for spatially variable capture rates when estimating movement probabilities with capture-recapture data. Longer-term studies are needed to evaluate temporal variability in stream fish passage at culverts (e.g., in relation to streamflow variability) and to thereby better quantify the degree of population fragmentation caused by road-stream crossings with culverts. ?? American Fisheries Society 2009.
Yangyang Guo; Wei Li; Jiping He
Neural decoding is a procedure to acquire intended movement information from neural activity and generate movement commands to control external devices such as intelligent prostheses. In this study, monkey Astra was trained to accomplish a 3-D reach-to-grasp task, and we recorded neural signals from its primary motor cortex (M1) during the task. The task-related cells were divided into four classes based on their correlation with two movement parameters: movement direction and orientation. We adopted the simple k-nearest neighbor (KNN) algorithm as the classifier, and chose cells from appropriate cell classes for movement parameter decoding. Cell classification was shown improving decoding accuracy with relatively less cells, even during movement planning stage (CRT). High decoding accuracy before movement actually performed is of great significance for intelligent prostheses control, and provides evidence that M1 is more than accepting ready-made movement commands but also participating in movement planning. We also found that population of task-related cells in M1 had a preference for specific direction and orientation, and this preference was more significant when it came to population of direction-related cells and orientation-related cells.
Full Text Available Technology aided measures offer a sensitive, accurate and time-efficient approach for the assessment of sensorimotor function after neurological insult compared to standard clinical assessments. This study investigated the sensitivity of robotic measures to capture differences in planar reaching movements as a function of neurological status (stroke, healthy, direction (front, ipsilateral, contralateral, movement segment (outbound, inbound, and time (baseline, post-training, 2-week follow-up using a planar, two-degrees of freedom, robotic-manipulator (H-Man. Twelve chronic stroke (age: 55±10.0 years, 5 female, 7 male, time since stroke: 11.2±6.0 months and nine aged-matched healthy participants (age: 53±4.3 years, 5 female, 4 male participated in this study. Both healthy and stroke participants performed planar reaching movements in contralateral, ipsilateral and front directions with the H-Man, and the robotic measures, spectral arc length (SAL, normalized time to peak velocities 〖(T〗_peakN, and root-mean square error (RMSE were evaluated. Healthy participants went through a one-off session of assessment to investigate the baseline. Stroke participants completed a 2-week intensive robotic training plus standard arm therapy (8 x 90 minute sessions. Motor function for stroke participants was evaluated prior to training (baseline, week-0, immediately following training (post-training, week-2, and 2-weeks after training (follow-up, week-4 using robotic assessment and the clinical measures Fugl-Meyer Assessment (FMA, Activity-Research-Arm Test (ARAT, and grip-strength. Robotic assessments were able to capture differences due to neurological status, movement direction, and movement segment. Movements performed by stroke participants were less-smooth, featured longer T_peakN, and larger RMSE values, compared to healthy controls. Significant movement direction differences were observed, with improved reaching performance for the front, compared
Santello, Marco; Lang, Catherine E.
The intact nervous system has an exquisite ability to modulate the activity of multiple muscles acting at one or more joints to produce an enormous range of actions. Seemingly simple tasks, such as reaching for an object or walking, in fact rely on very complex spatial and temporal patterns of muscle activations. Neurological disorders such as stroke and focal dystonia affect the ability to coordinate multi-joint movements. This article reviews the state of the art of research of muscle syner...
Mortensen, Peter Stendahl
that, in order to prevent bias, ratings per group must be used as reading probabilities. Nevertheless, in most cases, the estimates are still biased compared with panel data, thus overestimating net ´reach. Models with the same assumptions as with assignments of reading probabilities are presented......The author evaluates two different ways of estimating reach and frequency of plans for printed media. The first assigns reading probabilities to groups of respondents and calculates reach and frequency by simulation. the second estimates parameters to a model for reach/frequency. It is concluded...
Ran, L.; Garcia, T.; Ye, S.; Harman, C. J.; Hassan, M. A.; Simon, A.
Several reaches of Goodwin Creek, an experimental watershed within the Mississippi river basin, were analyzed for the period 1977-2007 in terms of long-term trends in sediment gain and loss in each reach, the relation of input and output to within-reach sediment fluxes, and the impacts of land use and bank erosion on reach sediment dynamics. Over the period 1977-2007, degradational and aggradational reaches were identified indicating slight vertical adjustment along the mainstream. Lateral adjustment was the main response of the channel to changes in flow and sediment regimes. Event-based sediment load was estimated using suspended concentration data, bedload transport rate, and changes in cross-sectional data. Bank erosion was estimated using cross-sectional data and models. The spatial and temporal patterns of within-reach sediment dynamics correspond closely with river morphology and also reflect basin conditions over the last three decades; thus they are conditioned by coeval trends in climate, hydrology, and land use. The sediment exchange within the mainstream was calculated by the development of reach sediment balances that reveal complex spatial and temporal patterns of sediment dynamics. Sediment load during the rising limb of the hydrograph was slightly higher than those estimated for the falling limb indicating the relative importance of sediment supply on reach sediment dynamic in the basin. Cumulative plots of sediment exchange reveal that major changes in within reach sediment storage are associated with large floods or major inputs from bank erosion.
Lilly, M. Stephen; Smith, Paula
Social movements are defined, the extent to which special education fits common definitions of social movements is assessed, and the life cycle of social movements is examined with particular focus on implications for special education. (Author)
Desai, Uday; Snavely, Keith
Bulgaria's environmental movement played a role in ending communist rule, but environmental issues were not completely resolved. Social movements may never achieve their objectives in totality but instead enter a new cycle of the movement. (SK)
Laban Movement Analysis is a system that helps dancers recognize and define the variety of elements that make up the movement event. This is not a method of teaching a movement style, but provides a means for creative expression. (DF)
Pfoser, D.; Jensen, Christian Søndergaard
With the proliferation of mobile computing, the ability to index efficiently the movements of mobile objects becomes important. Objects are typically seen as moving in two-dimensional (x,y) space, which means that their movements across time may be embedded in the three-dimensional (x,y,t) space...... is to reduce movements to occur in one spatial dimension. As a consequence, the movement occurs in two-dimensional (x,t) space. The advantages of considering such lower-dimensional trajectories are that the overall size of the data is reduced and that lower-dimensional data is to be indexed. Since off......-the-shelf database management systems typically do not offer higher-dimensional indexing, this reduction in dimensionality allows us to use existing DBMSes to store and index trajectories. Moreover, we argue that, given the right circumstances, indexing these dimensionality-reduced trajectories can be more efficient...
Full Text Available In this selective review, we examine key findings on eye movements when viewing advertisements. We begin with a brief, general introduction to the properties and neural underpinnings of saccadic eye movements. Next, we provide an overview of eye movement behavior during reading, scene perception, and visual search, since each of these activities is, at various times, involved in viewing ads. We then review the literature on eye movements when viewing print ads and warning labels (of the kind that appear on alcohol and tobacco ads, before turning to a consideration of advertisements in dynamic media (television and the Internet. Finally, we propose topics and methodological approaches that may prove to be useful in future research.
This article considers the development of the Tea Party movement, the character of its thinking and the nature of the interests and constituencies to which it is tied. The article suggests that despite the importance of ideas and interests, and the process of interaction between them, the movement...... has also been shaped and energised by institutional arrangements. In particular, it argues that there are significant numbers of independent or ‘detached’ conservatives and that the institutional architecture draws them towards political engagement but at the same time imposes constraints....... The political friction that this creates has contributed to the anger that has characterised the movement. While the Tea Party movement may, as such, have only an ephemeral existence, independent conservatives are likely to remain a significant and potent constituency and will, within the institutional...
Antón Fernández de Rota Irimia
Full Text Available The present article tries to rethink social movements from a poststructuralist position, going beyond Synthesis Theory. For the last twenty years the synthesis of the theories of Resource Mobilization, Political Opportunity and Cognitive Framing has been taken to be the last word in the sociology of social movements. Nevertheless, far from being any sort of advance, Synthesis Theory has merely perpetuated previous theories, without, in my opinion,managing to reconceptualize the constitution of power, or the force and embodiment of movement. The lack of theoretical attention to the definition of movement is a curious absence which needs to be redressed . My aim is approach it not from the notion of "subject" or any other type of "institution", but rather in terms of the contingencies of everyday life.
CHEVALOT, N; WANG, X; DORIOT, N
In order to investigate the computationally ill-posed problems related to the kinematic redundancy in both task and joint space of human movements, the present work aims to extend the work done by Wang (1999) and to study trunk-assisted upper limb reaching movements. In particular, the influence of pushing direction on the control of hand trajectory and upper limb movements was studied. The purpose of the paper is to present the main results of this investigation.
The purpose of the reported study is to discover an effective method of characterizing movement patterns of the crucial articulator as the function of an abstract syllable magnitude and the adjacent boundary, and at the same time to investigate effects of prosodic control on utterance organization. In particular, the speed of movement when a flesh point on the tongue blade or the lower lip crosses a selected position relative to the occlusion plane is examined. The time of such crossing provides an effective measure of syllable timing and syllable duration according to previous work. In the present work, using a very limited vocabulary with only a few consonants and one vowel as the key speech materials, effects of contrastive emphasis on demisyllabic movement patterns were studied. The theoretical framework for this analysis is the C/D model of speech production in relation to the concept of an invariant part of selected articulatory movements. The results show evidence in favor of the existence of ``iceberg'' patterns, but a linear dependence of slope on the total excursion of the demisyllabic movement, instead of the approximate constancy of the threshold crossing speed as suggested in the original proposal of the iceberg, has been found. Accordingly, a revision of the original concept of iceberg, seems necessary. This refinement is consistent with the C/D model assumption on ``prominence control'' that the syllable magnitude determines the movement amplitude, accompanying directly related syllable duration change. In this assumption, the movement of a consonantal component should also be proportional to syllable magnitude. The results suggests, however, systematic outliers deviating from the linear dependence of movement speed on excursion. This deviation may be caused by the effect of the immediately following boundary, often referred to as phrase-final elongation. Thesis advisor: Osamu Fujimura Copies of this thesis written in English can be obtained from
Bodily movement has long been employed as a foundation for cultivating mental skills such as attention, self-control or mindfulness, with recent studies documenting the positive impacts of mindful movement training, such as yoga and tai chi. A parallel “mind-body connection” has also been observed in many developmental disorders. We elaborate a spectrum of mindfulness by considering ADHD, in which deficient motor control correlates with impaired (disinhibited) behavioral control contributing ...
Hälbig, Thomas D; Borod, Joan C; Frisina, Pasquale G; Tse, Winona; Voustianiouk, Andrei; Olanow, C Warren; Gracies, Jean-Michel
Emotions can affect various aspects of human behavior. The impact of emotions on behavior is traditionally thought to occur at central, cognitive and motor preparation stages. Using EMG to measure the effects of emotion on movement, we found that emotional stimuli differing in valence and arousal elicited highly specific effects on peripheral movement time. This result has conceptual implications for the emotion-motion link and potentially practical implications for neurorehabilitation and professional environments where fast motor reactions are critical.
Peter James Ifft
Full Text Available The ability to inhibit unwanted movements and change motor plans is essential for behaviors of advanced organisms. The neural mechanisms by which the primate motor system rejects undesired actions have received much attention during the last decade, but it is not well understood how this neural function could be utilized to improve the efficiency of brain-machine interfaces (BMIs. Here we employed linear discriminant analysis (LDA and a Wiener filter to extract motor plan transitions from the activity of ensembles of sensorimotor cortex neurons. Two rhesus monkeys, chronically implanted with multielectrode arrays in primary motor (M1 and primary sensory (S1 cortices, were overtrained to produce reaching movements with a joystick towards visual targets upon their presentation. Then, the behavioral task was modified to include a distracting target that flashed for 50, 150 or 250 ms (25% of trials each followed by the true target that appeared at a different screen location. In the remaining 25% of trials, the initial target stayed on the screen and was the target to be approached. M1 and S1 neuronal activity represented both the true and distracting targets, even for the shortest duration of the distracting event. This dual representation persisted both when the monkey initiated movements towards the distracting target and then made corrections and when they moved directly towards the second, true target. The Wiener filter effectively decoded the location of the true target, whereas the LDA classifier extracted the location of both targets from ensembles of 50-250 neurons. Based on these results, we suggest developing real-time BMIs that inhibit unwanted movements represented by brain activity while enacting the desired motor outcome concomitantly.
Full Text Available When interacting with our environment we generally make use of egocentric and allocentric object information by coding object positions relative to the observer or relative to the environment, respectively. Bayesian theories suggest that the brain integrates both sources of information optimally for perception and action. However, experimental evidence for egocentric and allocentric integration is sparse and has only been studied using abstract stimuli lacking ecological relevance. Here, we investigated the use of egocentric and allocentric information during memory-guided reaching to images of naturalistic scenes. Participants encoded a breakfast scene containing six objects on a table (local objects and three objects in the environment (global objects. After a 2s delay, a visual test scene reappeared for 1s in which one local object was missing (=target and of the remaining, one, three or five local objects or one of the global objects were shifted to the left or to the right. The offset of the test scene prompted participants to reach to the target as precisely as possible. Only local objects served as potential reach targets and thus were task-relevant. When shifting objects we predicted accurate reaching if participants only used egocentric coding of object position and systematic shifts of reach endpoints if allocentric information were used for movement planning. We found that reaching movements were largely affected by allocentric shifts showing an increase in endpoint errors in the direction of object shifts with the number of local objects shifted. No effect occurred when one local or one global object was shifted. Our findings suggest that allocentric cues are indeed used by the brain for memory-guided reaching towards targets in naturalistic visual scenes. Moreover, the integration of egocentric and allocentric object information seems to depend on the extent of changes in the scene.
McMahon, Kathryn; van Dijk, Kor-Jent; Ruiz-Montoya, Leonardo; Kendrick, Gary A; Krauss, Siegfried L; Waycott, Michelle; Verduin, Jennifer; Lowe, Ryan; Statton, John; Brown, Eloise; Duarte, Carlos
A movement ecology framework is applied to enhance our understanding of the causes, mechanisms and consequences of movement in seagrasses: marine, clonal, flowering plants. Four life-history stages of seagrasses can move: pollen, sexual propagules, vegetative fragments and the spread of individuals through clonal growth. Movement occurs on the water surface, in the water column, on or in the sediment, via animal vectors and through spreading clones. A capacity for long-distance dispersal and demographic connectivity over multiple timeframes is the novel feature of the movement ecology of seagrasses with significant evolutionary and ecological consequences. The space-time movement footprint of different life-history stages varies. For example, the distance moved by reproductive propagules and vegetative expansion via clonal growth is similar, but the timescales range exponentially, from hours to months or centuries to millennia, respectively. Consequently, environmental factors and key traits that interact to influence movement also operate on vastly different spatial and temporal scales. Six key future research areas have been identified.
Brittany L Thomas
Full Text Available The Dual Visuomotor Channel Theory proposes that visually guided reaching is a composite of two movements, a Reach that advances the hand to contact the target and a Grasp that shapes the digits for target purchase. The theory is supported by biometric analyses of adult reaching, evolutionary contrasts, and differential developmental patterns for the Reach and the Grasp in visually guided reaching in human infants. The present ethological study asked whether there is evidence for a dissociated development for the Reach and the Grasp in nonvisual hand use in very early infancy. The study documents a rich array of spontaneous self-touching behavior in infants during the first six months of life and subjects the movements to analyses of body target, contact type, and Grasp. Video recordings were made of resting alert infants biweekly from birth to 6 months. In younger infants, self-touching targets included the head and trunk. As infants aged, targets became more caudal including the hips, legs, and feet. In younger infants hand contact was mainly made with the dorsum of the hand, but as infants aged contacts included palmar and eventually grasp and manipulatory contacts with the body and clothes. The relative incidence of caudal contacts and palmar contacts increased concurrently and were significantly correlated throughout the period of study. In contrast, developmental increases in self grasping emerged a few weeks after the increases observed in caudal and palmar contacts. The behavioral and temporal pattern of these spontaneous self-touching movements suggest that the Reach, in which the hand extends to make a palmar self-contact, and the Grasp, in which the digits close and make manipulatory movements, have partially independent developmental profiles. The results additionally suggest that self-touching behavior is an important developmental phase that allows for the coordination of the Reach and the Grasp prior to their use under visual
Sorensen, J A; Munksgaard, E C
In cavities with no support for inlays, polymerization contraction of the resin cement may move the ceramic inlay axially. The purpose of this study was to determine the velocity and extent of such movement. Cylindrical ceramic inlays were placed in dentin cavities filled with one of four commercially available resin composite cements. An initial standardized 200-microns-thick cement film was created. The movement of the ceramic inlay during polymerization of one of the resin cements was measured by a dial gauge. The velocity of the inlay movement decreased exponentially with time and with a velocity constant of 0.09 min-1. The majority of the movement occurred within the first 12 min after photopolymerization and probably continued for several days, reaching an estimated value of 5.8 microns. After 1-2 d of water storage, 1-2-microns contraction gaps at the cavity floors were observed microscopically for every cement used. It is concluded that in cavities without support for the inlay, about 2/3 of the resin cement contraction results in movement of the inlay and about 1/3 results in formation of gaps at the cavity floors.
Full Text Available Mirror movements are simultaneous, involuntary, identical movements occurring during contralateral voluntary movements. These movements are considered as soft neurologic signs seen uncommonly in clinical practice. The mirror movements are described in various neurological disorders which include parkinsonism, cranio veretebral junction anamolies, and hemiplegic cerebral palsy. These movements are intriguing and can pose significant disability. However, no such observation regarding mirror movements in progressive hemifacial atrophy have been reported previously. We are reporting a teenage girl suffering from progressive hemifacial atrophy and epilepsy with demonstrable mirror movements in hand.
Verma, Rajesh; Dixit, Puneet Kumar; Lalla, Rakesh; Singh, Babita
Mirror movements are simultaneous, involuntary, identical movements occurring during contralateral voluntary movements. These movements are considered as soft neurologic signs seen uncommonly in clinical practice. The mirror movements are described in various neurological disorders which include parkinsonism, cranio veretebral junction anamolies, and hemiplegic cerebral palsy. These movements are intriguing and can pose significant disability. However, no such observation regarding mirror movements in progressive hemifacial atrophy have been reported previously. We are reporting a teenage girl suffering from progressive hemifacial atrophy and epilepsy with demonstrable mirror movements in hand. PMID:26019431
Wedebye, Eva Bay; Nikolov, Nikolai Georgiev; Dybdahl, Marianne;
(Q)SAR models were applied to screen around 68,000 REACH pre-registered substances for CMR properties (carcinogenic, mutagenic or toxic to reproduction). Predictions from 14 relevant models were combined to reach overall calls for C, M and R. Combining predictions may reduce “noise” and increase...
G K Singh; K E Holé
Conventionally, the parameters of a sliding mode controller (SMC) are selected so as to reduce the time spent in the reaching mode. Although, an upper bound on the time to reach (reaching time) the sliding surface is easily derived, performance guarantee in the state/error space needs more consideration. This paper addresses the design of constant plus proportional rate reaching law-based SMC for second-order nonlinear systems. It is shown that this controller imposes a bounding second-order error-dynamics, and thus guarantees robust performance during the reaching phase. The choice of the controller parameters based on the time to reach a desirable level of output tracking error (OTE), rather than on the reaching time is proposed. Using the Lyapunov theory, it is shown that parameter selections, based on the reaching time criterion, may need substantially larger time to achieve the OTE. Simulation results are presented for a nonlinear spring-massdamper system. It is seen that parameter selections based on the proposed OTE criterion, result in substantially quicker tracking, while using similar levels of control effort.
Scullion, Kathleen; Boychuk, Jeffery A; Yamakawa, Glenn R; Rodych, Justin T G; Nakanishi, Stan T; Seto, Angela; Smith, Victoria M; McCarthy, Ryan W; Whelan, Patrick J; Antle, Michael C; Pittman, Quentin J; Teskey, G Campbell
Serotonin has a myriad of central functions involving mood, appetite, sleep, and memory and while its release within the spinal cord is particularly important for generating movement, the corresponding role on cortical movement representations (motor maps) is unknown. Using adult rats we determined that pharmacological depletion of serotonin (5-HT) via intracerebroventricular administration of 5,7 dihydroxytryptamine resulted in altered movements of the forelimb in a skilled reaching task as well as higher movement thresholds and smaller maps derived using high-resolution intracortical microstimulation (ICMS). We ruled out the possibility that reduced spinal cord excitability could account for the serotonin depletion-induced changes as we observed an enhanced Hoffman reflex (H-reflex), indicating a hyperexcitable spinal cord. Motor maps derived in 5-HT1A receptor knock-out mice also showed higher movement thresholds and smaller maps compared with wild-type controls. Direct cortical application of the 5-HT1A/7 agonist 8-OH-DPAT lowered movement thresholds in vivo and increased map size in 5-HT-depleted rats. In rats, electrical stimulation of the dorsal raphe lowered movement thresholds and this effect could be blocked by direct cortical application of the 5-HT1A antagonist WAY-100135, indicating that serotonin is primarily acting through the 5-HT1A receptor. Next we developed a novel in vitro ICMS preparation that allowed us to track layer V pyramidal cell excitability. Bath application of WAY-100135 raised the ICMS current intensity to induce action potential firing whereas the agonist 8-OH-DPAT had the opposite effect. Together our results demonstrate that serotonin, acting through 5-HT1A receptors, plays an excitatory role in forelimb motor map expression.
Aimola, Ettore; Santello, Marco; La Grua, Giovanni; Casabona, Antonino
Anticipatory postural adjustments (APAs) are thought to compensate for upcoming and predictable perturbations before they occur, e.g., a backward shift of the body center of pressure (COP) before raising the arm. When the goal of arm movements is to reach, grasp, and manipulate an object, predicting the effect of raising the arm on body COP before reach onset could incorporate the properties of the object to be lifted, as both will affect postural control during reaching and object manipulation. Alternatively, the central nervous system (CNS) might use separate APAs to compensate for the effect of arm raising from raising the arm and object. To distinguish between these two scenarios, we asked subjects to reach, grasp, and lift an object whose mass (100g, 750g, or 1400g) was either constant across trials or variable from trial to trial ('predictable' and 'unpredictable' condition, respectively). We hypothesized that object mass would affect the magnitude of APAs in the predictable condition before the onset of object lift but not before the initial arm onset. We also expected COP variability following object lift to be reduced as a result of APAs. For the unpredictable condition, we expected 'default' APAs that would minimize postural perturbation following object lift. We found that both magnitude and timing of APAs were modulated as a function of predictable object mass prior to contact, rather than at the onset of the reaching movement. Specifically, COP position moved forward with increasing object load (p<0.05) and peak COP velocity related to object contact occurred significantly early for heavier loads (p<0.05). For the random condition, the COP position and timing at all loads resembled that associated with larger predictable loads. These findings suggest that modulating COP to a future event might be more accurate when timed to temporally close events, thus potentially reducing the computational load as well as risks of prediction errors. Additionally, our
Jose M Carmena
Full Text Available Reaching and grasping in primates depend on the coordination of neural activity in large frontoparietal ensembles. Here we demonstrate that primates can learn to reach and grasp virtual objects by controlling a robot arm through a closed-loop brain-machine interface (BMIc that uses multiple mathematical models to extract several motor parameters (i.e., hand position, velocity, gripping force, and the EMGs of multiple arm muscles from the electrical activity of frontoparietal neuronal ensembles. As single neurons typically contribute to the encoding of several motor parameters, we observed that high BMIc accuracy required recording from large neuronal ensembles. Continuous BMIc operation by monkeys led to significant improvements in both model predictions and behavioral performance. Using visual feedback, monkeys succeeded in producing robot reach-and-grasp movements even when their arms did not move. Learning to operate the BMIc was paralleled by functional reorganization in multiple cortical areas, suggesting that the dynamic properties of the BMIc were incorporated into motor and sensory cortical representations.
James Y Liao
Full Text Available We have demonstrated that 3D target-oriented human arm reaches can be represented as linear combinations of discrete submovements, where the submovements are a set of minimum-jerk basis functions for the reaches. We have also demonstrated the ability of deterministic feed-forward Artificial Neural Networks (ANNs to predict the parameters of the submovements. ANNs were trained using kinematic data obtained experimentally from five human participants making target-directed movements that were decomposed offline into minimum-jerk submovements using an optimization algorithm. Under cross-validation, the ANNs were able to accurately predict the parameters (initiation-time, amplitude, and duration of the individual submovements. We also demonstrated that the ANNs can together form a closed-loop model of human reaching capable of predicting 3D trajectories with VAF >95.9% and RMSE ≤4.32 cm relative to the actual recorded trajectories. This closed-loop model is a step towards a practical arm trajectory generator based on submovements, and should be useful for the development of future arm prosthetic devices that are controlled by brain computer interfaces or other user interfaces.
Dukelow Sean P
Full Text Available Abstract Background Several studies have found correlations between proprioception and visuomotor function during stroke recovery, however two more recent studies have found no correlation. Unfortunately, most of the studies to date have been conducted with clinical assessments of sensation that are observer-based and have poor reliability. We have recently developed new tests to assess position sense and motor function using robotic technology. The present study was conducted to reassess the relationship between position sense and upper limb movement following stroke. Methods We assessed position sense and motor performance of 100 inpatient stroke rehabilitation subjects and 231 non-disabled controls. All subjects completed quantitative assessments of position sense (arm-position matching task and motor performance (visually-guided reaching task using the KINARM robotic device. Subjects also completed clinical assessments including handedness, vision, Purdue Pegboard, Chedoke-McMaster Stroke Assessment-Impairment Inventory and Functional Independence Measure (FIM. Neuroimaging documented lesion localization. Fisher’s exact probability tests were used to determine the relationship between performances on the arm-position matching and visually-guided reaching task. Pearson’s correlations were conducted to determine the relationship between robotically measured parameters and clinical assessments. Results Performance by individual subjects on the matching and reaching tasks was statistically independent (Fisher’s test, P Conclusions Our data support the concept that position sense deficits are functionally relevant and point to the importance of assessing proprioceptive and motor impairments independently when planning treatment strategies.
Shroder, John F.; Weihs, Brandon J.; Schettler, Megan Jensen
Mass movements of nearly all types occur in Afghanistan but in the high relief, rugged Pamir and Hindu Kush mountains of northeastern Afghanistan, mass-movement threats to lives and property necessitated study to elucidate problems to development. Twenty-two different mass movements in bedrock in the Badakhshan Province of northeastern Afghanistan were studied for this paper, including large rock falls and rock slides, along with massive slope-failure complexes with many types and rates of movement. Where higher altitudes prevail in the region, ice-cemented and ice-cored rock glaciers are also common and overlie some of the other mass movements. Inasmuch as seismic energy sources in the Eastern Hindu Kush are maximal in southern Badakhshan, and relief, slope angles and precipitation all increase from west to east as well, the causes of the pervasive mass movement are plentiful enough, although direct cause and slope-failure effect are not known. Some weak sedimentary lithologies downfaulted into, or draped across crystalline rocks, also failed. Some intermixed tills also occur but are not easily differentiated, even with analysis on the ground. Using high resolution satellite imagery and digital elevation models, we assessed geomorphologic parameters to characterize spatial-organization structures related to zones of erosion, deposition and further hazard potential. Analyses indicate that many of the massive slope failures can be characterized and differentiated into various process domains and chronologic-development zones with their different impacts upon the landscape. Mass movements in Afghanistan can exhibit unique topographic signatures that can be used to better assess hazards in other mountain areas, especially where landslide-dam breakout floods threaten. Development of roads, bridges, buildings, and irrigation networks should be done with care in these regions of Afghanistan.
Full Text Available Bodily movement has long been employed as a foundation for cultivating mental skills such as attention, self-control or mindfulness, with recent studies documenting the positive impacts of mindful movement training, such as yoga and tai chi. A parallel mind-body connection has also been observed in many developmental disorders. We elaborate a spectrum of mindfulness by considering ADHD, in which deficient motor control correlates with impaired (disinhibited behavioral control contributing to defining features of excessive distractibility and impulsivity. These data provide evidence for an important axis of variation for wellbeing, in which skillful cognitive control covaries with a capacity for skillful movement. We review empirical and theoretical literature on attention, cognitive control, mind wandering, mindfulness and skill learning, endorsing a model of skilled attention in which motor plans, attention, and executive goals are seen as mutually co-defining aspects of skilled behavior that are linked by reciprocal inhibitory and excitatory connections. Thus, any movement training should engage higher-order inhibition and selection and develop a repertoire of rehearsed procedures that coordinate goals, attention and motor plans. However, we propose that mindful movement practice may improve the functional quality of rehearsed procedures, cultivating a transferrable skill of attention. We adopt Langer’s spectrum of mindful learning that spans from mindlessness to engagement with the details of the present task and contrast this with the mental attitudes cultivated in standard mindfulness meditation. We particularly follow Feldenkrais’ suggestion that mindful learning of skills for organizing the body in movement might transfer to other forms of mental activity. The results of mindful movement training should be observed in multiple complementary measures, and may have tremendous potential benefit for individuals with ADHD and other
Clark, Dav; Schumann, Frank; Mostofsky, Stewart H
Bodily movement has long been employed as a foundation for cultivating mental skills such as attention, self-control or mindfulness, with recent studies documenting the positive impacts of mindful movement training, such as yoga and tai chi. A parallel "mind-body connection" has also been observed in many developmental disorders. We elaborate a spectrum of mindfulness by considering ADHD, in which deficient motor control correlates with impaired (disinhibited) behavioral control contributing to defining features of excessive distractibility and impulsivity. These data provide evidence for an important axis of variation for wellbeing, in which skillful cognitive control covaries with a capacity for skillful movement. We review empirical and theoretical literature on attention, cognitive control, mind wandering, mindfulness and skill learning, endorsing a model of skilled attention in which motor plans, attention, and executive goals are seen as mutually co-defining aspects of skilled behavior that are linked by reciprocal inhibitory and excitatory connections. Thus, any movement training should engage "higher-order" inhibition and selection and develop a repertoire of rehearsed procedures that coordinate goals, attention and motor plans. However, we propose that mindful movement practice may improve the functional quality of rehearsed procedures, cultivating a transferrable skill of attention. We adopt Langer's spectrum of mindful learning that spans from "mindlessness" to engagement with the details of the present task and contrast this with the mental attitudes cultivated in standard mindfulness meditation. We particularly follow Feldenkrais' suggestion that mindful learning of skills for organizing the body in movement might transfer to other forms of mental activity. The results of mindful movement training should be observed in multiple complementary measures, and may have tremendous potential benefit for individuals with ADHD and other populations.
Oltmanns, J; Bunke, D; Jenseit, W; Heidorn, C
The REACH Regulation represents a major piece of chemical legislation in the EU and requires manufacturers and importers of chemicals to assess the safety of their substances. The classification of substances for their hazards is one of the crucial elements in this process. We analysed the effect of REACH on classification for human health endpoints by comparing information from REACH registration dossiers with legally binding, harmonised classifications. The analysis included 142 chemicals produced at very high tonnages in the EU, the majority of which have already been assessed in the past. Of 20 substances lacking a harmonised classification, 12 chemicals were classified in REACH registration dossiers. More importantly, 37 substances with harmonised classifications for human health endpoints had stricter classifications in registration dossiers and 29 of these were classified for at least one additional endpoint not covered by the harmonised classification. Substance-specific analyses suggest that one third of these additional endpoints emerged from experimental studies performed to fulfil information requirements under REACH, while two thirds resulted from a new assessment of pre-REACH studies. We conclude that REACH leads to an improved hazard characterisation even for substances with a potentially good data basis.
The following article explains the EU chemical regulation "REACH', explicates the requirements that Chinese producers are facing, and shows how they can fulfill the requirements and secure their access to the EU market. The consequences of failing to fulfill REACH requirements are given in REACH Article 5: No data, no market: ... substances ... in articles ... shall not be ... placed on the market unless they have been registered In other words: Without registration of chemicals Chinese producers of electric household appliances may loose their EU market.
Full Text Available The purpose of this paper is to summarize results on various aspects of sets with positive reach, which are up to now not available in such a compact form. After recalling briefly the results before 1959, sets with positive reach and their associated curvature measures are introduced. We develop an integral and current representation of these curvature measures and show how the current representation helps to prove integralgeometric formulas, such as the principal kinematic formula. Also random sets with positive reach and random mosaics (or the more general random cell-complexes with general cell shape are considered.
Ciavarro, Marco; Ambrosini, Ettore; Tosoni, Annalisa; Committeri, Giorgia; Fattori, Patrizia; Galletti, Claudio
Unexpected changes in the location of a target for an upcoming action require both attentional reorienting and motor planning update. In both macaque and human brain, the medial posterior parietal cortex is involved in both phenomena but its causal role is still unclear. Here we used on-line rTMS over the putative human V6A (pV6A), a reach-related region in the dorsal part of the anterior bank of the parieto-occipital sulcus, during an attention and a reaching task requiring covert shifts of attention and planning of reaching movements toward cued targets in space. We found that rTMS increased RTs to invalidly cued but not to validly cued targets during both the attention and reaching task. Furthermore, we found that rTMS induced a deviation of reaching endpoints toward visual fixation and that this deviation was larger for invalidly cued targets. The results suggest that reorienting signals are used by human pV6A area to rapidly update the current motor plan or the ongoing action when a behaviorally relevant object unexpectedly occurs in an unattended location. The current findings suggest a direct involvement of the action-related dorso-medial visual stream in attentional reorienting and a more specific role of pV6A area in the dynamic, on-line control of reaching actions.
Reference materials that deal with various aspects of theater movement are grouped in this partially annotated bibliography under the following headings: anatomy, kinesiology, and physiology; combat and martial arts; integrated approaches to movement; mime; miscellaneous acting and movement approaches; movement notations systems; movement…
Benjamin W Tatler
Full Text Available The impact of Yarbus's research on eye movements was enormous following the translation of his book Eye Movements and Vision into English in 1967. In stark contrast, the published material in English concerning his life is scant. We provide a brief biography of Yarbus and assess his impact on contemporary approaches to research on eye movements. While early interest in his work focused on his study of stabilised retinal images, more recently this has been replaced with interest in his work on the cognitive influences on scanning patterns. We extended his experiment on the effect of instructions on viewing a picture using a portrait of Yarbus rather than a painting. The results obtained broadly supported those found by Yarbus.
Full Text Available In recent years, there has been a focus on reducing energy consumption in commercial buildings as a means of increasing their sustainability. As part of this trend, various health clubs and fitness centers have been designed to lower consumption of resources such as electricity and water. However, energy consumption is just one part of sustainability, with human health and economic health also paramount. When all components of sustainability are analyzed, other forms of physical activity may possess higher levels of sustainability than traditional gym exercise. Natural movement activity consists of outdoor activity that replicates movements performed by ancient humans during the Paleolithic era. A full analysis of sustainability shows that natural movement activity consumes fewer resources and provides unique psychological and physical benefits compared with traditional indoor exercise.
Thomsen, Bente Dahl
This paper presents the good practice based experiences found when movement is used to strengthen form creation and to create flow in the process of artistic education. Faced with the design engineering students’ problems with creating forms with aesthetic statements, the experiences with movement...... inspired the thesis that the design engineers’ training in aesthetic form creation can be improved by integrating the movement potential into their education. The paper documents the on-going work on developing a model for embodied creation of form called ‘Somatechne model’. The study also identifies...... a lens to assess the students’ development of mind-body skills, known as ‘The Three Soma’. The Somatechne model also helps to identify the activity that gives the students the opportunity to develop their sensibility and thus aesthetic attention....
Pacific States Marine Fisheries Commission — This feature class includes the POLYGON waterbody features from the 2001 version of the PNW River Reach files Arc/INFO coverage. Separate, companion feature classes...
Wong, Elaine; Amaya Fernández, Ferney Orlando; Tafur Monroy, Idelfonso
The merging of access and metro networks has been proposed as a solution to lower the unit cost of customer bandwidth. This paper reviews some of the recent advances and challenges in extended-reach optical access networks....
Pacific States Marine Fisheries Commission — This feature class includes the ARC features from the 2001 version of the PNW River Reach files Arc/INFO coverage. Separate, companion feature classes are also...
US Fish and Wildlife Service, Department of the Interior — The Snively Basin area of the Arid Lands Ecology Reserve (ALE) within the Hanford Reach National Monument was historically used to farm cereal rye, among other...
US Fish and Wildlife Service, Department of the Interior — The Weather Station Fire (July, 2005) burned across 4,918 acres in the Saddle Mountain Unit of the Hanford Reach National Monument, which included parts of the...
Erb, Christopher D; Moher, Jeff; Sobel, David M; Song, Joo-Hyun
The current study uses reach tracking to investigate how cognitive control is implemented during online performance of the Stroop task (Experiment 1) and the Eriksen flanker task (Experiment 2). We demonstrate that two of the measures afforded by reach tracking, initiation time and reach curvature, capture distinct patterns of effects that have been linked to dissociable processes underlying cognitive control in electrophysiology and functional neuroimaging research. Our results suggest that initiation time reflects a response threshold adjustment process involving the inhibition of motor output, while reach curvature reflects the degree of co-activation between response alternatives registered by a monitoring process over the course of a trial. In addition to shedding new light on fundamental questions concerning how these processes contribute to the cognitive control of behavior, these results present a framework for future research to investigate how these processes function across different tasks, develop across the lifespan, and differ among individuals.
US Fish and Wildlife Service, Department of the Interior — The Saddle Lakes Fire of 2015 burned 14,200 acres of habitat on Saddle Mountain National Wildlife Refuge, part of the Hanford Reach National Monument. Within the...
California Department of Resources — The shapefile is based on habitat unit level data summarized at the stream reach level. The database represents salmonid stream habitat surveys from 645 streams of...
US Fish and Wildlife Service, Department of the Interior — The Snively Basin area of the Arid Lands Ecology Reserve within the Hanford Reach National Monument was historically used to farm cereal rye (Secale cereale), among...
... gov/news/fullstory_162538.html Birth Defects From Zika More Far-Reaching Than Thought Studies found greater ... 14, 2016 WEDNESDAY, Dec. 14, 2016 (HealthDay News) -- Zika's ability to damage the infant brain may be ...
Ritter, Ellen M.; Welch, Diane T.
Describes a project conducted by the Texas Agricultural Extension Service to market the Family Day Home Care Providers Program to an unknown clientele. Discusses the problems involved in identifying and reaching the target audience. (JOW)
Juravle, Georgiana; Heed, Tobias; Spence, Charles; Röder, Brigitte
Tactile information is differentially processed over the various phases of goal-directed movements. Here, event-related potentials (ERPs) were used to investigate the neural correlates of tactile and visual information processing during movement. Participants performed goal-directed reaches for an object placed centrally on the table in front of them. Tactile and visual stimulation (100 ms) was presented in separate trials during the different phases of the movement (i.e. preparation, execution, and post-movement). These stimuli were independently delivered to either the moving or resting hand. In a control condition, the participants only performed the movement, while omission (i.e. movement-only) ERPs were recorded. Participants were instructed to ignore the presence or absence of any sensory events and to concentrate solely on the execution of the movement. Enhanced ERPs were observed 80-200 ms after tactile stimulation, as well as 100-250 ms after visual stimulation: These modulations were greatest during the execution of the goal-directed movement, and they were effector based (i.e. significantly more negative for stimuli presented to the moving hand). Furthermore, ERPs revealed enhanced sensory processing during goal-directed movements for visual stimuli as well. Such enhanced processing of both tactile and visual information during the execution phase suggests that incoming sensory information is continuously monitored for a potential adjustment of the current motor plan. Furthermore, the results reported here also highlight a tight coupling between spatial attention and the execution of motor actions.
This paper examines the far - reaching influence of anti - dam movement on the protection of environment in the second half of the 20th century in American West. It first introduces the historical background of dams built along the Colorado Biver - the most important river in the West, especially the construction of Hoover Dam and Glen Canyon Dam. Then, the criticism of dams on the Colorado is examined with the emphasis on the anti - dam movement resulting from the awareness of the negative ecological impacts on the Colorado. In the conclusion, the author demonstrates the unparallel historical significance of the anti -dam movement in the en-vironmentalism in developing the American West.
Price, Kelly J.; Shiffrar, Maggie; Kerns, Kimberly A.
To determine whether motor difficulties documented in Asperger's Syndrome (AS) are related to compromised visual abilities, this study examined perception and movement in response to dynamic visual environments. Fourteen males with AS and 16 controls aged 7-23 completed measures of motor skills, postural response to optic flow, and visual…
Various research studies concerned with the feedback from proprioceptors which accompany movement and the way in which this information is relevant to the control of activity are brought together in this volume. It is intended for the use of those who have some basic knowledge of human anatomy and physiology as well as an acquaintance with…
Full Text Available Neuropsychological and neuroimaging data suggest a differential contribution of posterior parietal regions during the different components of a transitive gesture. Reaching requires the integration of object location and body position coordinates and reaching tasks elicit bilateral activation in different foci along the intraparietal sulcus. Grasping requires a visuomotor match between the object’s shape and the hand’s posture. Lesion studies and neuroimaging confirm the importance of the anterior part of the intraparietal sulcus for human grasping. Reaching and grasping reveal bilateral activation that is generally more prominent on the side contralateral to the hand used or the hemifield stimulated. Purposeful behavior with objects and tools can be assessed in a variety of ways, including actual use, pantomimed use, and pure imagery of manipulation. All tasks have been shown to elicit robust activation over the left parietal cortex in neuroimaging, but lesion studies have not always confirmed these findings. Compared to pantomimed or imagined gestures, actual object and tool use typically produces activation over the left primary somatosensory region. Neuroimaging studies on pantomiming or imagery of tool use in healthy volunteers revealed neural responses in possibly separate foci in the left supramarginal gyrus. In sum, the parietal contribution of reaching and grasping of objects seems to depend on a bilateral network of intraparietal foci that appear organized along gradients of sensory and effector preferences. Dorsal and medial parietal cortex appears to contribute to the online monitoring/adjusting of the ongoing prehensile action, whereas the functional use of objects and tools seems to involve the inferior lateral parietal cortex. This functional input reveals a clear left lateralized activation pattern that may be tuned to the integration of acquired knowledge in the planning and guidance of the transitive movement.
Neuropsychological and neuroimaging data suggest a differential contribution of posterior parietal regions during the different components of a transitive gesture. Reaching requires the integration of object location and body position coordinates and reaching tasks elicit bilateral activation in different foci along the intraparietal sulcus. Grasping requires a visuomotor match between the object's shape and the hand's posture. Lesion studies and neuroimaging confirm the importance of the anterior part of the intraparietal sulcus for human grasping. Reaching and grasping reveal bilateral activation that is generally more prominent on the side contralateral to the hand used or the hemifield stimulated. Purposeful behavior with objects and tools can be assessed in a variety of ways, including actual use, pantomimed use, and pure imagery of manipulation. All tasks have been shown to elicit robust activation over the left parietal cortex in neuroimaging, but lesion studies have not always confirmed these findings. Compared to pantomimed or imagined gestures, actual object and tool use typically produces activation over the left primary somatosensory region. Neuroimaging studies on pantomiming or imagery of tool use in healthy volunteers revealed neural responses in possibly separate foci in the left supramarginal gyrus. In sum, the parietal contribution of reaching and grasping of objects seems to depend on a bilateral network of intraparietal foci that appear organized along gradients of sensory and effector preferences. Dorsal and medial parietal cortex appears to contribute to the online monitoring/adjusting of the ongoing prehensile action, whereas the functional use of objects and tools seems to involve the inferior lateral parietal cortex. This functional input reveals a clear left lateralized activation pattern that may be tuned to the integration of acquired knowledge in the planning and guidance of the transitive movement.
Batcho, C S; Gagné, M; Bouyer, L J; Roy, J S; Mercier, C
When subjects learn a novel motor task, several sources of feedback (proprioceptive, visual or auditory) contribute to the performance. Over the past few years, several studies have investigated the role of visual feedback in motor learning, yet evidence remains conflicting. The aim of this study was therefore to investigate the role of online visual feedback (VFb) on the acquisition and retention stages of motor learning associated with training in a reaching task. Thirty healthy subjects made ballistic reaching movements with their dominant arm toward two targets, on 2 consecutive days using a robotized exoskeleton (KINARM). They were randomly assigned to a group with (VFb) or without (NoVFb) VFb of index position during movement. On day 1, the task was performed before (baseline) and during the application of a velocity-dependent resistive force field (adaptation). To assess retention, participants repeated the task with the force field on day 2. Motor learning was characterized by: (1) the final endpoint error (movement accuracy) and (2) the initial angle (iANG) of deviation (motor planning). Even though both groups showed motor adaptation, the NoVFb-group exhibited slower learning and higher final endpoint error than the VFb-group. In some condition, subjects trained without visual feedback used more curved initial trajectories to anticipate for the perturbation. This observation suggests that learning to reach targets in a velocity-dependent resistive force field is possible even when feedback is limited. However, the absence of VFb leads to different strategies that were only apparent when reaching toward the most challenging target.
Kuang, Shenbing; Morel, Pierre; Gail, Alexander
Neurons in the posterior parietal cortex respond selectively for spatial parameters of planned goal-directed movements. Yet, it is still unclear which aspects of the movement the neurons encode: the spatial parameters of the upcoming physical movement (physical goal), or the upcoming visual limb movement (visual goal). To test this, we recorded neuronal activity from the parietal reach region while monkeys planned reaches under either normal or prism-reversed viewing conditions. We found predominant encoding of physical goals while fewer neurons were selective for visual goals during planning. In contrast, local field potentials recorded in the same brain region exhibited predominant visual goal encoding, similar to previous imaging data from humans. The visual goal encoding in individual neurons was neither related to immediate visual input nor to visual memory, but to the future visual movement. Our finding suggests that action planning in parietal cortex is not exclusively a precursor of impending physical movements, as reflected by the predominant physical goal encoding, but also contains spatial kinematic parameters of upcoming visual movement, as reflected by co-existing visual goal encoding in neuronal spiking. The co-existence of visual and physical goals adds a complementary perspective to the current understanding of parietal spatial computations in primates.
Zubair, Humza N; Beloozerova, Irina N; Sun, Hai; Marlinski, Vladimir
Knowledge of how the head moves during locomotion is essential for understanding how locomotion is controlled by sensory systems of the head. We have analyzed head movements of the cat walking along a straight flat pathway in the darkness and light. We found that cats' head left-right translations, and roll and yaw rotations oscillated once per stride, while fore-aft and vertical translations, and pitch rotations oscillated twice. The head reached its highest vertical positions during second half of each forelimb swing, following maxima of the shoulder/trunk by 20-90°. Nose-up rotation followed head upward translation by another 40-90° delay. The peak-to-peak amplitude of vertical translation was ∼1.5cm and amplitude of pitch rotation was ∼3°. Amplitudes of lateral translation and roll rotation were ∼1cm and 1.5-3°, respectively. Overall, cats' heads were neutral in roll and 10-30° nose-down, maintaining horizontal semicircular canals and utriculi within 10° of the earth horizontal. The head longitudinal velocity was 0.5-1m/s, maximal upward and downward linear velocities were ∼0.05 and ∼0.1m/s, respectively, and maximal lateral velocity was ∼0.05m/s. Maximal velocities of head pitch rotation were 20-50°/s. During walking in light, cats stood 0.3-0.5cm taller and held their head 0.5-2cm higher than in darkness. Forward acceleration was 25-100% higher and peak-to-peak amplitude of head pitch oscillations was ∼20°/s larger. We concluded that, during walking, the head of the cat is held actively. Reflexes appear to play only a partial role in determining head movement, and vision might further diminish their role.
Foth, H; Hayes, Aw
Industrial chemicals have been in use for many decades and new products are regularly invented and introduced to the market. Also for decades, many different chemical laws have been introduced to regulate safe handling of chemicals in different use patterns. The patchwork of current regulation in the European Union is to be replaced by the new regulation on industrial chemical control, REACH. REACH stands for registration, evaluation, and authorization of chemicals. REACH entered force on June 1, 2007. REACH aims to overcome limitations in testing requirements of former regulation on industrial chemicals to enhance competitiveness and innovation with regard to manufacture safer substances and to promote the development of alternative testing methods. A main task of REACH is to address data gaps regarding the properties and uses of industrial chemicals. Producers, importers, and downstream users will have to compile and communicate standard information for all chemicals. Information sets to be prepared include safety data sheets (SDS), chemical safety reports (CSR), and chemical safety assessments (CSA). These are designed to guarantee adequate handling in the production chain, in transport and in use and to prevent the substances from being released to and distributed within the environment. Another important aim is to identify the most harmful chemicals and to set incentives to substitute them with safer alternatives. On one hand, REACH will have substantial impact on the basic understanding of the evaluation of chemicals. However, the toxicological sciences can also substantially influence the workability of REACH that supports the transformation of data to the information required to understand and manage acceptable and non acceptable risks in the use of industrial chemicals. The REACH regulation has been laid down in the main document and 17 Annexes of more than 849 pages. Even bigger technical guidance documents will follow and will inform about the rules for
Grimme, Britta; Lipinski, John; Schöner, Gregor
By studying human movement in the laboratory, a number of regularities and invariants such as planarity and the principle of isochrony have been discovered. The theoretical idea has gained traction that movement may be generated from a limited set of movement primitives that would encode these invariants. In this study, we ask if invariants and movement primitives capture naturalistic human movement. Participants moved objects to target locations while avoiding obstacles using unconstrained arm movements in three dimensions. Two experiments manipulated the spatial layout of targets, obstacles, and the locations in the transport movement where an obstacle was encountered. We found that all movement trajectories were planar, with the inclination of the movement plane reflecting the obstacle constraint. The timing of the movement was consistent with both global isochrony (same movement time for variable path lengths) and local isochrony (same movement time for two components of the obstacle avoidance movement). The identified movement primitives of transport (movement from start to target position) and lift (movement perpendicular to transport within the movement plane) varied independently with obstacle conditions. Their scaling accounted for the observed double peak structure of movement speed. Overall, the observed naturalistic movement was astoundingly regular. Its decomposition into primitives suggests simple mechanisms for movement generation.
Two strands of futurism share values of equality, development, and peace, and can catalyze each other into potentially transformational forces. The path is re-education: World order thinking provides an appropriate content for adult learning, and women's movements provide the energy of commitment and a worldwide network for communicating policies.…
Castellini, Greta; Gianola, Silvia; Banzi, Rita;
on randomized controlled trials (RCTs) included in a Cochrane systematic review on the effectiveness of constraint-induced movement therapy (CIMT) for stroke patients. METHODS: We extracted data on the functional independence measure (FIM) and the action research arm test (ARAT) from RCTs that compared CIMT...
Nielsen, Jakob Isak
Just like art historians have focused on e.g. composition or lighting, this dissertation takes a single stylistic parameter as its object of study: camera movement. Within film studies this localized avenue of middle-level research has become increasingly viable under the aegis of a perspective k...
Luechinger, Annemarie B.; Hadders-Algra, Mijna; Van Kan, Colette M.; de Vries, JIP
Perinatal qualitative assessment of general movements (GMs) is a tool to evaluate the integrity of the young nervous system. The aim of this investigation was to study the emergence of GMs. Fetal onset of GMs was studied sonographically in 18 fetuses during the first trimester of uncomplicated in vi
Full Text Available From the beginning of the Occupy Movement, poetry has occupied a major supporting role. Both the New York and Boston encampments immediately set up a library tent, and poetry readings were a regular part of the camp’s activities.
VON BARAVALLE, HERMANN
AN HISTORICAL REVIEW OF THE WALDORF SCHOOL PLAN TRACES THE MOVEMENT FROM ITS FOUNDING IN STUTTGART, GERMANY IN 1919, BY THE WALDORF ASTORIA COMPANY AND UNDER THE DIRECTION OF RUDOLF STEINER, TO ITS INTRODUCTION INTO SWITZERLAND, OTHER EUROPEAN COUNTRIES, THE AMERICAS, AUSTRALIA, NEW ZEALAND, AND SOUTH AFRICA, A TOTAL OF 175 SCHOOLS AS OF 1963. THE…
Full Text Available Abstract Background The notion 'hard to reach' is a contested and ambiguous term that is commonly used within the spheres of social care and health, especially in discourse around health and social inequalities. There is a need to address health inequalities and to engage in services the marginalized and socially excluded sectors of society. Methods This paper describes a pilot study involving interviews with representatives from eight Voluntary and Community Sector (VCS organisations. The purpose of the study was to explore the notion of 'hard to reach' and perceptions of the barriers and facilitators to accessing services for 'hard to reach' groups from a voluntary and community sector perspective. Results The 'hard to reach' may include drug users, people living with HIV, people from sexual minority communities, asylum seekers, refugees, people from black and ethnic minority communities, and homeless people although defining the notion of the 'hard to reach' is not straight forward. It may be that certain groups resist engaging in treatment services and are deemed hard to reach by a particular service or from a societal stance. There are a number of potential barriers for people who may try and access services, including people having bad experiences in the past; location and opening times of services and how services are funded and managed. A number of areas of commonality are found in terms of how access to services for 'hard to reach' individuals and groups could be improved including: respectful treatment of service users, establishing trust with service users, offering service flexibility, partnership working with other organisations and harnessing service user involvement. Conclusions If health services are to engage with groups that are deemed 'hard to reach' and marginalised from mainstream health services, the experiences and practices for engagement from within the VCS may serve as useful lessons for service improvement for
Richter, Jonas N; Hochner, Binyamin; Kuba, Michael J
The motor control of the eight highly flexible arms of the common octopus (Octopus vulgaris) has been the focus of several recent studies. Our study is the first to manage to introduce a physical constraint to an octopus arm and investigate the adaptability of stereotypical bend propagation in reaching movements and the pseudo-limb articulation during fetching. Subjects (N=6) were placed inside a transparent Perspex box with a hole at the center that allowed the insertion of a single arm. Animals had to reach out through the hole toward a target, to retrieve a food reward and fetch it. All subjects successfully adjusted their movements to the constraint without an adaptation phase. During reaching tasks, the animals showed two movement strategies: stereotypical bend propagation reachings, which were established at the hole of the Perspex box and variant waving-like movements that showed no bend propagations. During fetching movements, no complete pseudo-joint fetching was observed outside the box and subjects pulled their arms through the hole in a pull-in like movement. Our findings show that there is some flexibility in the octopus motor system to adapt to a novel situation. However, at present, it seems that these changes are more an effect of random choices between different alternative motor programs, without showing clear learning effects in the choice between the alternatives. Interestingly, animals were able to adapt the fetching movements to the physical constraint, or as an alternative explanation, they could switch the motor primitive fetching to a different motor primitive 'arm pulling'.
Full Text Available The birth of Jamaah Tabligh was in fact a direct reaction to the emergence of aggressive Hindu proselytization movement, such as the Shuddhi (Purifying and Sangathan (Consolidation movement, which made wide-reaching attempt in the early 20th century to "return" to Hinduism those who had "left" the religion and converted to Islam during the period of Muslim political power in India. The main target of these right-wing Hindu movements were those they called "borderline Muslims" who still maintained many beliefs and cultural habit that had come from Hinuism. Maulana Muhammad Ilyas, founder of Jamaah Tabligh, believed that only a grass-roots Islamic movement could challenge the effort of Shuddhi and Sangathan, thought "purifying" these "borderline" Muslims and educating them about basic faith and worship in order to save them from the process of Hindunisation.Copyright (c 2014 by SDI. All right reserved.DOI: 10.15408/sdi.v11i3.596
Petit, Odile; Bon, Richard
Besides focusing on the adaptive significance of collective movements, it is crucial to study the mechanisms and dynamics of decision-making processes at the individual level underlying the higher-scale collective movements. It is now commonly admitted that collective decisions emerge from interactions between individuals, but how individual decisions are taken, i.e. how far they are modulated by the behaviour of other group members, is an under-investigated question. Classically, collective movements are viewed as the outcome of one individual's initiation (the leader) for departure, by which all or some of the other group members abide. Individuals assuming leadership have often been considered to hold a specific social status. This hierarchical or centralized control model has been challenged by recent theoretical and experimental findings, suggesting that leadership can be more distributed. Moreover, self-organized processes can account for collective movements in many different species, even in those that are characterized by high cognitive complexity. In this review, we point out that decision-making for moving collectively can be reached by a combination of different rules, i.e. individualized (based on inter-individual differences in physiology, energetic state, social status, etc.) and self-organized (based on simple response) ones for any species, context and group size.
Lee, H M; Bhat, A; Scholz, J P; Galloway, J C
Our recent work on the initial emergence of reaching identified a mosaic of developmental changes and consistencies within the hand and joint kinematics of arm movements across the pre-reaching period. The purpose of this study was to test hypotheses regarding the coordination of hand and joint kinematics over this same pre-reaching period. Principal component analysis (PCA) was conducted on hand, shoulder, and elbow kinematic data from 15 full-term infants observed biweekly from 8 weeks of age through the week of reach onset. Separate PCAs were calculated for spatial variables and for velocity variables in trials with a toy and without a toy. From the PCA results, we constructed 'variance profiles' to reflect the coordinative structure of the hand, shoulder, and elbow. By coordinative structure is meant here the relative contribution of each joint to the factors revealed by the PCA. Shifts in these profiles, which reflected coordination changes, were compared across the hand and joints within each pre-reaching phase (Early, Mid, Late) as well as across phases and trial conditions (no-toy and toy). Results identified both surprising consistencies and important developmental changes in coordination. First, over development, spatial coordination changed in different ways for the shoulder and elbow. Between the Early and Late phases, spatial coordination at the shoulder showed more adult-like coordination during both spontaneous movements and movements with a toy present. In contrast, elbow spatial coordination became more adult-like only during movements with a toy and less adult-like during spontaneous movements. Second, over development, velocity coordination became more adult-like at both joints in movements with and without a toy present. We propose that the features of coordination that changed over development suggest explanations for the differential roles and developmental trajectories of the control of arm movements between the shoulder and elbow. We propose
James Yu-Chang Liao
Full Text Available Brain-Computer Interfaces (BCIs that convert brain-recorded neural signals into intended movement commands could eventually be combined with Functional Electrical Stimulation to allow individuals with Spinal Cord Injury to regain effective and intuitive control of their paralyzed limbs. To accelerate the development of such an approach, we developed a model of closed-loop BCI control of arm movements that (1 generates realistic arm movements (based on experimentally measured, visually-guided movements with real-time error correction, (2 simulates cortical neurons with firing properties consistent with literature reports, and (3 decodes intended movements from the noisy neural ensemble. With this model we explored (1 the relative utility of neurons tuned for different movement parameters (position, velocity, and goal and (2 the utility of recording from larger numbers of neurons – critical issues for technology development and for determining appropriate brain areas for recording. We simulated arm movements that could be practically restored to individuals with severe paralysis, i.e., movements from an armrest to a volume in front of the person. Performance was evaluated by calculating the smallest movement endpoint target radius within which the decoded cursor position could dwell for one second. Our results show that goal, position, and velocity neurons all contribute to improve performance. However, velocity neurons enabled smaller targets to be reached in shorter amounts of time than goal or position neurons. Increasing the number of neurons also improved performance, although performance saturated at 30-50 neurons for most neuron types. Overall, our work presents a closed-loop BCI simulator that models error corrections and the firing properties of various movement-related neurons that can be easily modified to incorporate different neural properties. We anticipate that this kind of tool will be important for development of future BCIs.
McFarland, Dennis J.; Sarnacki, William A.; Wolpaw, Jonathan R.
Brain-computer interfaces (BCIs) can use brain signals from the scalp (EEG), the cortical surface (ECoG), or within the cortex to restore movement control to people who are paralyzed. Like muscle-based skills, BCIs' use requires activity-dependent adaptations in the brain that maintain stable relationships between the person's intent and the signals that convey it. This study shows that humans can learn over a series of training sessions to use EEG for three-dimensional control. The responsible EEG features are focused topographically on the scalp and spectrally in specific frequency bands. People acquire simultaneous control of three independent signals (one for each dimension) and reach targets in a virtual three-dimensional space. Such BCI control in humans has not been reported previously. The results suggest that with further development noninvasive EEG-based BCIs might control the complex movements of robotic arms or neuroprostheses.
Nathan, Dominic; Jeutter, Dean C
Reaching-to-grasp is essential for the performance of activities of daily living. Pathologies such as stroke, spinal cord injury, cerebral palsy, etc. limit individuals from being able to perform meaningful upper extremity movements, leading to a reduced quality of life. Robotic aided therapy is gaining prevalence as a rehabilitation tool because it can provide consistent and quantitative therapy. Such systems are dependent upon models to generate trajectories that dictate their movements. Time scaled polynomial techniques have been extensively used for robotic model development and trajectory generation. However, this approach is limited because it cannot support functional therapy tasks. This is largely due to the influence of cognitive complexity not completely considered with regards to the activity performed. We examine the influence of task cognitive complexity as manifested through the geometric properties of each object on the movement trajectories and kinematic dependent variables tasks through a motion analysis study using healthy subjects (N=8). We then compare the predicted results from several robotic trajectory models with the actual motion analysis data. Our results show that there are differences present, between the trajectory data and kinematic properties for each task, that are specific to the geometric properties of each object. In addition, the predicted results from the robotic trajectory models do not fully correlate with the actual movement information. This study is important as it will help provide some insight with regards to factors that need to be considered during the development of future robotic trajectory models and controllers for upper extremity functional rehabilitation tasks.
Bédard, Patrick; Proteau, Luc
We studied aiming performance of adults for video- and manual aiming tasks when they had visual information about the location of the starting base or when they had not. In video-aiming, foveating the starting base and then the target prior to movement initiation (Foveation) resulted in less aiming bias and variability than when the starting base was not visible (PNV), or visible without the participants foveating it prior to movement initiation (PSV). In manual aiming, Foveation and PSV procedures resulted in identical results but reduced aiming bias and variability in comparison to the PNV procedures. The results indicate that participants had difficulty in transforming the locations of the starting base and of the target when seen on a vertical screen into an appropriate movement trajectory. Successive foveation of the starting base and of the target facilitated this transformation, resulting in direction variability being reduced by more than half in comparison to the PNV and PSV conditions. This suggests that in video-aiming the efference copy of the saccade can be used by the CNS to approximate the hand trajectory in the workspace and/or in joint coordinates (Jouffrais and Boussaoud, 1999). Hand trajectory could be readily available in manual aiming if the target location can be recoded directly in hand-coordinates as recently suggested by Buneo et al. (2002).
Richard A. Horsley
Full Text Available This article investigates the origins and development of the earliest Jesus movements within the context of persistent conflict between the Judean and Galilean peasantry and their Jerusalem and Roman rulers. It explores the prominence of popular prophetic and messianic movements and shows how the earliest movements that formed in response to Jesus’ mission exhibit similar features and patterns. Jesus is not treated as separate from social roles and political-economic relationships. Viewing Jesus against the background of village communities in which people lived, the Gospels are understood as genuine communication with other people in historical social contexts. The article argues that the net effect of these interrelated factors of theologically determined New Testament interpretation is a combination of assumptions and procedures that would be unacceptable in the regular investigation of history. Another version of the essay was published in Horsley, Richard A (ed, A people’s history of Christianity, Volume 1: Christian origins, 23-46. Minneapolis, MN: Fortress.
Su, Kuei-Jung; Hwang, Wen-Juh; Wu, Ching-yi; Fang, Jing-Jing; Leong, Iat-Fai; Ma, Hui-Ing
Research has shown that moving targets help Parkinson's disease (PD) patients improve their arm movement while sitting. We examined whether increasing the speed of a moving ball would also improve standing postural control in PD patients during a virtual reality (VR) ball-catching task. Twenty-one PD patients and 21 controls bilaterally reached to catch slow-moving and then fast-moving virtual balls while standing. A projection-based VR system connected to a motion-tracking system and a force platform was used. Dependent measures included the kinematics of arm movement (movement time, peak velocity), duration of anticipatory postural adjustments (APA), and center of pressure (COP) movement (movement time, maximum amplitude, and average velocity). When catching a fast ball, both PD and control groups made arm movements with shorter movement time and higher peak velocity, longer APA, as well as COP movements with shorter movement time and smaller amplitude than when catching a slow ball. The change in performance from slow- to fast-ball conditions was not different between the PD and control groups. The results suggest that raising the speed of virtual moving targets should increase the speed of arm and COP movements for PD patients. Therapists, however, should also be aware that a fast virtual moving target causes the patient to confine the COP excursion to a smaller amplitude. Future research should examine the effect of other task parameters (e.g., target distance, direction) on COP movement and examine the long-term effect of VR training.
Burke, David T; Meleger, Alec; Schneider, Jeffrey C; Snyder, Jim; Dorvlo, Atsu S S; Al-Adawi, Samir
This study tests the relation between eye-movements and thought processing. Subjects were given specific modality tasks (visual, gustatory, kinesthetic) and assessed on whether they responded with distinct eye-movements. Some subjects' eye-movements reflected ongoing thought processing. Instead of a universal pattern, as suggested by the neurolinguistic programming hypothesis, this study yielded subject-specific idiosyncratic eye-movements across all modalities. Included is a discussion of the neurolinguistic programming hypothesis regarding eye-movements and its implications for the eye-movement desensitization and reprocessing theory.