Bimanual motor coordination in older adults is associated with increased functional brain connectivity--a graph-theoretical analysis.

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.

Cortical regions involved in the observation of bimanual actions.

Although we are beginning to understand how observed actions performed by conspecifics with a single hand are processed and how bimanual actions are controlled by the motor system, we know very little about the processing of observed bimanual actions. We used fMRI to compare the observation of bimanual manipulative actions with their unimanual components, relative to visual control conditions equalized for visual motion. Bimanual action observation did not activate any region specialized for processing visual signals related to this more elaborated action.

Microstructural organization of corpus callosum projections to prefrontal cortex predicts bimanual motor learning.

The corpus callosum (CC) is the largest white matter tract in the brain. It enables interhemispheric communication, particularly with respect to bimanual coordination. Here, we use diffusion tensor imaging (DTI) in healthy humans to determine the extent to which structural organization of subregions within the CC would predict how well subjects learn a novel bimanual task.

Graph analysis of functional brain networks for cognitive control of action in traumatic brain injury.

Patients with traumatic brain injury show clear impairments in behavioural flexibility and inhibition that often persist beyond the time of injury, affecting independent living and psychosocial functioning. Functional magnetic resonance imaging studies have shown that patients with traumatic brain injury typically show increased and more broadly dispersed frontal and parietal activity during performance of cognitive control tasks. We constructed binary and weighted functional networks and calculated their topological properties using a graph theoretical approach.

Diffusion tensor imaging metrics of the corpus callosum in relation to bimanual coordination: effect of task complexity and sensory feedback.

When manipulating objects with both hands, the corpus callosum (CC) is of paramount importance for interhemispheric information exchange. Hence, CC damage results in impaired bimanual performance. Here, healthy young adults performed a complex bimanual dial rotation task with or without augmented visual feedback and according to five interhand frequency ratios (1:1, 1:3, 2:3, 3:1, 3:2).

Testing multiple coordination constraints with a novel bimanual visuomotor task.

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.

Impaired eye movements in post-concussion syndrome indicate suboptimal brain function beyond the influence of depression, malingering or intellectual ability.

Post-concussion syndrome (PCS) can affect up to 20%-30% of patients with mild closed head injury (mCHI), comprising incomplete recovery and debilitating persistence of post-concussional symptoms. Eye movements relate closely to the functional integrity of the injured brain and eye movement function is impaired post-acutely in mCHI. Here, we examined whether PCS patients continue to show disparities in eye movement function at 3-5 months following mCHI compared with patients with good recovery.

A new approach to predicting postconcussion syndrome after mild traumatic brain injury based upon eye movement function.

Following on from our earlier findings of a close relationship between motor function and outcome after mild traumatic brain injury (mTBI), this study examined whether it might be possible to predict poor recovery in the form of postconcussion syndrome (PCS) based upon early eye and arm motor function. Within 1 week post-injury, we assessed 37 mTBI patients on measures of saccades, oculomotor smooth pursuit, upper-limb visuomotor function, neuropsychological status, and self-reported health condition. At 3 months, 8 patients met the criteria for PCS.

Recovery in the first year after mild head injury: divergence of symptom status and self-perceived quality of life.

Objective: To examine self-perceived health status during the first year following mild closed head injury.

Methods: At 1 week, and at 3, 6 and 12 months post-injury, 37 patients with mild closed head injury completed written versions of the Rivermead Post-Concussion Symptoms Questionnaire (RPSQ), the Rivermead Head-Injury Follow-up Questionnaire (RHIFQ) and the SF-36 Health Survey. Thirty-seven controls provided baselines for the SF-36 and the RPSQ.

Mild head injury--a close relationship between motor function at 1 week post-injury and overall recovery at 3 and 6 months.

Based on previous findings of impaired eye and arm motor control after mild closed head injury (CHI), this study examined whether early eye and arm motor function, and the level of post-injury cerebral dysfunction manifested in motor control, relates systematically to recovery at 3 and 6 months after mild CHI. At 1 week post-injury, we assessed oculomotor function, upper-limb visuomotor performance, and cognitive status in 37 mild CHI patients. Re-examination at 3 and 6 months determined outcome in terms of postconcussional symptoms and performance of everyday tasks, as assessed by the Rivermead Postconcussion Symptoms Questionnaire, the Rivermead Head Injury Follow-up Questionnaire and the SF-36 Health Survey.

Motor deficits and recovery during the first year following mild closed head injury.

Objective: This study examined motor impairments over 1 year following mild closed head injury (CHI). It is the first study to serially assess long-term oculomotor and upper-limb visuomotor function following mild head trauma.

Methods: Thirty-seven patients with mild CHI and 37 matched controls were compared at 1 week, 3 months and 6 months and 31 available pairs at 12 months post-injury on measures of saccades, oculomotor smooth pursuit, upper-limb visuomotor function and neuropsychological performance.

Distribution of microstructural damage in the brains of professional boxers: a diffusion MRI study.

Purpose: To investigate and localize cerebral abnormalities in professional boxers with no history of moderate or severe head trauma.

Materials And Methods: Diffusion tensor imaging (DTI) was used to determine the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in the brains of 81 professional male boxers and 12 male control subjects. Voxel-based analysis (VBA) of both the diffusion and anisotropy values was performed using statistical parametric mapping (SPM).

The impact of mild closed head injury on involuntary saccadic adaptation: evidence for the preservation of implicit motor learning.

Objective: Mild closed head injury (CHI) can impair performance on volitional saccades (fast eye movements), with poorer saccade accuracy being one of the principal deficits. Assessing a patient group with known deficits of volitional saccades, the authors investigated whether mild CHI similarly impairs the implicit adaptation of visually-guided (reflexive) saccades, an important process which maintains saccadic accuracy.

Methods: Within 2 weeks following mild CHI, 30 patients and 30 matched controls were compared on a computerized paradigm, which artificially induced saccadic adaptation.

Eye movement and visuomotor arm movement deficits following mild closed head injury.

Based on increasing evidence that even mild closed head injury (CHI) can cause considerable neural damage throughout the brain, we hypothesized that mild CHI will disrupt the complex cerebral networks concerned with oculomotor and upper-limb visuomotor control, resulting in impaired motor function. Within 10 days following mild CHI (Glasgow Coma Scale 13-15, alteration of consciousness <20 min), we compared 30 patients (15-37 years) and 30 matched controls on different types of saccades, oculomotor smooth pursuit (sine and random), upper-limb visuomotor performance and several neuropsychological tests known to be sensitive to head trauma. Simple reflexive saccades were not impaired, whereas, on the antisaccade task, the CHI group demonstrated prolonged saccadic latencies, a marginally higher number of directional errors and poorer spatial accuracy.