Long-term motor learning in focal hand dystonia.

Objective: Because focal hand dystonia usually occurs in the over-learned stage, it would be valuable to know long-term motor learning characteristics and underlying pathophysiological features that might predispose to dystonia.

Methods: We conducted a case-control exploratory study of 15 visits over 12 weeks in the non-affected hand of a 4-finger sequence of 8 key presses in eight patients with FHD compared with eight age- and sex-matched, healthy volunteers (HVs). We studied the behavioral data and the physiological changes of the brain, including motor cortical excitability and cortical oscillations.

Hand Use and Grasp Sensor System in Monitoring Infant Fine Motor Development.

Objective: To assess the feasibility of a hand use and grasp sensor system in collecting and quantifying fine motor development longitudinally in an infant's home environment.

Design: Cohort study. Researchers made home visits monthly to participating families to collect grasp data from infants using a hand use and grasp sensor.

Hearing Safety From Single- and Double-Pulse Transcranial Magnetic Stimulation in Children and Young Adults.

Purpose: Concerns regarding hearing safety have limited the number of studies using transcranial magnetic stimulation (TMS) in children and young adults. The objective of this study was to examine the safety of TMS with regards to hearing in a group of 16 children and young adults (17.3 ± 4.

Neurophysiological features of tactile versus visual guidance of ongoing movement.

Although studies have investigated tactile and visual processing for perception, sensory processing for ongoing action remains poorly understood. The purpose of this study was to explore modality-specific patterns of cortical activation and functional connectivity in a practiced trajectory tracking task. Participants traced irregular shapes with their index finger using either touch or vision for guidance.

Inter-joint coordination analysis of reach-to-grasp kinematics in children and adolescents with obstetrical brachial plexus palsy.

Background: Obstetrical brachial plexus palsy is a common birth injury to nerves passing through the brachial plexus that may result in structural and functional abnormalities. Individual joint trajectories from kinematic analyses have been used to evaluate the source and extent of abnormalities. Here, two summary measures of limb kinematics were utilized: 1) the Arm Profile Score summarizing upper limb joint kinematic abnormalities from a typical pattern across a task, and 2) the recently developed Multi-joint Coordination Measure using principal component analysis to characterize typical coordination of multiple joints throughout a task and compute deviations in time and space.

Probing the interaction of the ipsilateral posterior parietal cortex with the premotor cortex using a novel transcranial magnetic stimulation technique.

Objective: Functional imaging studies have shown that control of planned movement involves a distributed network that involves the premotor (PMv) and posterior parietal cortices (PPC). Similarly, anatomical studies show that these regions are densely interconnected via white matter tracts. We therefore hypothesized that the PPC influence over the motor cortex is partly via a connection with the PMv.

Coordination of Reach-to-Grasp Kinematics in Individuals With Childhood-Onset Dystonia Due to Hemiplegic Cerebral Palsy.

Functional reaching is impaired in dystonia. Here, we analyze upper extremity kinematics to quantify timing and coordination abnormalities during unimanual reach-to-grasp movements in individuals with childhood-onset unilateral wrist dystonia. Kinematics were measured during movements of both upper limbs in a patient group ( n = 11, age = 17.

Distinct interneuronal networks influence excitability of the surround during movement initiation.

Surround inhibition (SI) is a feature of motor control in which activation of task-related muscles is associated with inhibition of neighboring, nonprotagonist muscles, allowing selective motor control. The physiological basis for SI still remains unknown. In all previous studies, SI in the motor system was measured during movement initiation by using transcranial magnetic stimulation (TMS) to deliver a posteroanterior current at a single suprathreshold intensity.

Cortical activation and inter-hemispheric sensorimotor coherence in individuals with arm dystonia due to childhood stroke.

Objective: Dystonia is a disabling motor disorder often without effective therapies. To better understand the genesis of dystonia after childhood stroke, we analyzed electroencephalographic (EEG) recordings in this population.

Methods: Resting spectral power of EEG signals over bilateral sensorimotor cortices (Powrest), resting inter-hemispheric sensorimotor coherence (Cohrest), and task-related changes in power (TRPow) and coherence (TRCoh) during wrist extension were analyzed in individuals with dystonia (age 20±3years) and healthy volunteers (age 17±5years).

Efficient and reliable characterization of the corticospinal system using transcranial magnetic stimulation.

Purpose: The purpose of this study is to develop a method to reliably characterize multiple features of the corticospinal system in a more efficient manner than typically done in transcranial magnetic stimulation studies.

Methods: Forty transcranial magnetic stimulation pulses of varying intensity were given over the first dorsal interosseous motor hot spot in 10 healthy adults. The first dorsal interosseous motor-evoked potential size was recorded during rest and activation to create recruitment curves.

Characteristics of bilateral hand function in individuals with unilateral dystonia due to perinatal stroke: sensory and motor aspects.

The authors assessed bilateral motor and sensory function in individuals with upper limb dystonia due to unilateral perinatal stroke and explored interrelationships of motor function and sensory ability. Reach kinematics and tactile sensation were measured in 7 participants with dystonia and 9 healthy volunteers. The dystonia group had poorer motor (hold time, reach time, shoulder/elbow correlation) and sensory (spatial discrimination, stereognosis) outcomes than the control group on the nondominant side.

Induction of motor associative plasticity in the posterior parietal cortex-primary motor network.

There is anatomical and functional connectivity between the primary motor cortex (M1) and posterior parietal cortex (PPC) that plays a role in sensorimotor integration. In this study, we applied corticocortical paired-associative stimuli to ipsilateral PPC and M1 (parietal ccPAS) in healthy right-handed subjects to test if this procedure could modulate M1 excitability and PPC-M1 connectivity. One hundred and eighty paired transcranial magnetic stimuli to the PPC and M1 at an interstimulus interval (ISI) of 8 ms were delivered at 0.

Cortical silent period duration and its implications for surround inhibition of a hand muscle.

Surround inhibition is a neural mechanism that assists in the focusing of excitatory drive to muscles responsible for a given movement (agonist muscles) by suppressing unwanted activity in muscles not relevant to the movement (surround muscles). The purpose of the study was to determine the contribution of γ-aminobutyric acid(B) receptor-mediated intracortical inhibition, as assessed by the cortical silent period (CSP), to the generation of surround inhibition in the motor system. Eight healthy adults (five women and three men, 29.

Contributors to excess antagonist activity during movement in children with secondary dystonia due to cerebral palsy.

Children with secondary dystonia due to cerebral palsy exhibit abnormal upper extremity postures and slow voluntary movement. However, the interaction between abnormal postures and abnormal movement in dystonia is still unclear. Some mechanisms by which postures are maintained in dystonia include stretch reflexes, overflow of muscle activation to other muscles, and direct coactivation of antagonist muscles.

Abnormalities of tactile sensory function in children with dystonic and diplegic cerebral palsy.

Recent studies have shown the presence of sensory dysfunction in adults with focal dystonias. The authors hypothesize that children with secondary dystonia due to cerebral palsy may share a similar sensory dysfunction. To test this hypothesis, they evaluated tactile spatial discrimination threshold using Johnson, Van Boven, Phillips domes in 10 children with cerebral palsy and upper extremity dystonia, 8 children with diplegic cerebral palsy without involvement of the arms, and 21 unaffected children.

Botulinum toxin type B improves the speed of reaching in children with cerebral palsy and arm dystonia: an open-label, dose-escalation pilot study.

Seven children between 2 and 15 years of age with cerebral palsy and upper extremity dystonia were enrolled in an open-label, dose-escalation pilot clinical trial of botulinum toxin type B (Myobloc), injected into the biceps and brachioradialis muscles of I or both arms. The primary outcome measure was the change in maximum speed of hand movement during attempted forward reaching. Escalating doses of 12.

The effects of trunk stimulation on bimanual seated workspace.

This study explores the effects of functional electrical stimulation (FES) of the lumbar trunk extensors on the seated posture and bimanual workspace of subjects with spinal cord injury (SCI). Four subjects with motor complete SCI with implanted intramuscular stimulating electrodes to activate the lumbar erector spinae were studied. The positions of markers on the pelvis, trunk, and hands were monitored by a motion capture system during bimanual reaching maneuvers.