Bimanual coordination and corpus callosum microstructure in young adults with traumatic brain injury: a diffusion tensor imaging study.

Bimanual actions are ubiquitous in daily life. Many coordinated movements of the upper extremities rely on precise timing, which requires efficient interhemispheric communication via the corpus callosum (CC). As the CC in particular is known to be vulnerable to traumatic brain injury (TBI), furthering our understanding of its structure-function association is highly valuable for TBI diagnostics and prognosis.

Involvement of the primary motor cortex in controlling movements executed with the ipsilateral hand differs between left- and right-handers.

Unimanual motor tasks, specifically movements that are complex or require high forces, activate not only the contralateral primary motor cortex (M1) but evoke also ipsilateral M1 activity. This involvement of ipsilateral M1 is asymmetric, such that the left M1 is more involved in motor control with the left hand than the right M1 in movements with the right hand. This suggests that the left hemisphere is specialized for movement control of either hand, although previous experiments tested mostly right-handed participants.

The neural basis of central proprioceptive processing in older versus younger adults: an important sensory role for right putamen.

Our sense of body position and movement independent of vision (i.e., proprioception) relies on muscle spindle feedback and is vital for performing motor acts.

Correlations between white matter integrity and motor function in traumatic brain injury patients.

Background: Deterioration of motor function is one of several clinical manifestations following traumatic brain injury (TBI) in children and adolescents.

Objective: To investigate the relationship between white matter (WM) integrity using diffusion tensor imaging (DTI) and motor functioning in young TBI patients.

Methods: A group with moderate to severe TBI (n = 24) and a control group (n = 17) were scanned using DTI along with standard anatomical scans.

Excitability of the motor cortex ipsilateral to the moving body side depends on spatio-temporal task complexity and hemispheric specialization.

Unilateral movements are mainly controlled by the contralateral hemisphere, even though the primary motor cortex ipsilateral (M1(ipsi)) to the moving body side can undergo task-related changes of activity as well. Here we used transcranial magnetic stimulation (TMS) to investigate whether representations of the wrist flexor (FCR) and extensor (ECR) in M1(ipsi) would be modulated when unilateral rhythmical wrist movements were executed in isolation or in the context of a simple or difficult hand-foot coordination pattern, and whether this modulation would differ for the left versus right hemisphere. We found that M1(ipsi) facilitation of the resting ECR and FCR mirrored the activation of the moving wrist such that facilitation was higher when the homologous muscle was activated during the cyclical movement.

Formation and hydrogen release of hydrazine bisborane: transfer vs. attachment of a borane.

The reactivity of hydrazine in the presence of diborane has been investigated using ab initio quantum chemical computations (MP2 and CCSD(T) methods with the aug-cc-pVTZ basis set). Portions of the relevant potential energy surface were constructed to probe the formation mechanism of the hydrazine diborane (BH(3)BH(3)NH(2)NH(2)) and hydrazine bisborane (BH(3)NH(2)NH(2)BH(3)). The differences between both adducts are established.

Reversal of optic disc cupping with improvement of visual field and stereometric parameters after trabeculectomy in young adult patients (two case reports).

The authors report two cases of mid- to long-term reversal of optic disc cupping after trabeculectomy with mitomycine-C in young adult patients suffering from secondary glaucoma. The cup to disc ratio reversed from 0.80 and 0.

Motor learning with augmented feedback: modality-dependent behavioral and neural consequences.

Sensory information is critical to correct performance errors online during the execution of complex tasks and can be complemented by augmented feedback (FB). Here, 2 groups of participants acquired a new bimanual coordination pattern under different augmented FB conditions: 1) visual input reflecting coordination between the 2 hands and 2) auditory pacing integrating the timing of both hands into a single temporal structure. Behavioral findings revealed that the visual group became dependent on this augmented FB for performance, whereas the auditory group performed equally well with or without augmented FB by the end of practice.

Continuation versus discontinuation of insulin secretagogues when initiating insulin in type 2 diabetes.

We compared the combined use of basal insulin, metformin and insulin secretagogues with a combination of basal insulin and metformin in patients with type 2 diabetes starting basal insulin analogue therapy. This analysis was part of a 24-week trial, in which 964 insulin-naive patients with type 2 diabetes inadequately controlled on oral agents (including metformin) were randomized to insulin glargine or detemir. Secretagogues were stopped or maintained at the site-investigators' discretion.

Three-dimensional reaching tasks: effect of reaching height and width on upper limb kinematics and muscle activity.

In previous studies, upper limb coordination was usually analyzed during two-dimensional (2D) arm movements. Based on joint kinematics and muscle activity, it has been demonstrated that the shoulder joint controls the multi-joint movement. This study focused on three-dimensional (3D) reaching tasks and examined if the coordination strategies previously described in 2D can be transferred to 3D movements and if reaching to different locations in space has an effect on kinematic and upper limb muscle strategies.

Hemispheric asymmetries of motor versus nonmotor processes during (visuo)motor control.

Language and certain aspects of motor control are typically served by the left hemisphere, whereas visuospatial and attentional control are lateralized to the right. Here a (visuo)motor tracing task was used to identify hemispheric lateralization beyond the general, contralateral organization of the motor system. Functional magnetic resonance imaging (fMRI) was applied in 40 male right-handers (19-30 yrs) during line tracing with dominant and nondominant hand, with and without visual guidance.

Orthodontic and orthognathic management of a patient with Apert syndrome: a case report.

This case report describes the combined orthodontic and orthognathic management of a 14-year-old girl affected with Apert syndrome. She presented with a severe Class III skeletal relationship, midfacial hypoplasia and an large anterior open bite. Intraorally, she had severe crowding, a narrow maxilla and lateral posterior crossbites.

The effect of long-term TENS on persistent neuroplastic changes in the human cerebral cortex.

The long-term effect of daily somatosensory stimulation with transcutaneous electrical nerve stimulation (TENS) on reorganization of the motor cortex was investigated in a group of neurologically intact humans. The scalp representation of the corticospinal projection to the finger (APB, ADM) and forearm (FCR, ECR) muscles was mapped by means of transcranial magnetic stimulation (TMS) before and after a 3-week intervention period, using map area and volume, and topographical overlaps between the cortical motor representations of these muscles as primary dependent measures. Findings revealed a significant increase in cortical motor representation of all four muscles for the TENS group from pre to posttest (all, P ≤ 0.

Action perception in individuals with congenital blindness or deafness: how does the loss of a sensory modality from birth affect perception-induced motor facilitation?

Seeing or hearing manual actions activates the mirror neuron system, that is, specialized neurons within motor areas which fire when an action is performed but also when it is passively perceived. Using TMS, it was shown that motor cortex of typically developed subjects becomes facilitated not only from seeing others' actions, but also from merely hearing action-related sounds. In the present study, TMS was used for the first time to explore the "auditory" and "visual" responsiveness of motor cortex in individuals with congenital blindness or deafness.

Formation and decomposition of chemically activated and stabilized hydrazine.

Recombination of two amidogen radicals, NH(2) (X(2)B1), is relevant to hydrazine formation, ammonia oxidation and pyrolysis, nitrogen reduction (fixation), and a variety of other N/H/X combustion, environmental, and interstellar processes. We have performed a comprehensive analysis of the N(2)H(4) potential energy surface, using a variety of theoretical methods, with thermochemical kinetic analysis and master equation simulations used to treat branching to different product sets in the chemically activated NH(2) + NH(2) process. For the first time, iminoammonium ylide (NH(3)NH), the less stable isomer of hydrazine, is involved in the kinetic modeling of N(2)H(4).

Dual-task interference during initial learning of a new motor task results from competition for the same brain areas.

Cerebral patterns of activity elicited by dual-task performance throughout the learning of a complex bimanual coordination pattern were addressed. Subjects (N=12) were trained on the coordination pattern and scanned using fMRI at early (PRE) and late (POST) learning stages. During scanning, the coordination pattern was performed either as a single task or in concurrence with a simultaneous visual search task (i.

Observing how others lift light or heavy objects: which visual cues mediate the encoding of muscular force in the primary motor cortex?

Observers are able to judge quite accurately the weights lifted by others. Only recently, neuroscience has focused on the role of the motor system to accomplish this task. In this respect, a previous transcranial magnetic stimulation (TMS) study showed that the muscular force requirements of an observed action are encoded by the primary motor cortex (M1).

Fast reactions of hydroxycarbenes: tunneling effect versus bimolecular processes.

Different uni- and bimolecular reactions of hydroxymethylene, an important intermediate in the photochemistry of formaldehyde, as well as its halogenated derivatives (XCOH, X = H, F, Cl, Br), have been considered using high-level CCSD(T)/CBS quantum chemical methods. The Wentzel-Kramers-Brillouin (WKB) and Eckart approximations were applied to estimate the tunneling rate constant of isomerization of trans-HCOH to H(2)CO, and the WKB procedure was found to perform better in this case. In agreement with recent calculations and experimental observations [Schreiner et al.

Force requirements of observed object lifting are encoded by the observer's motor system: a TMS study.

Several transcranial magnetic stimulation (TMS) studies have reported facilitation of the primary motor cortex (M1) during the mere observation of actions. This facilitation was shown to be highly congruent, in terms of somatotopy, with the observed action, even at the level of single muscles. With the present study, we investigated whether this muscle-specific facilitation of the observer's motor system reflects the degree of muscular force that is exerted in an observed action.

Hemispheric asymmetries of the premotor cortex are task specific as revealed by disruptive TMS during bimanual versus unimanual movements.

The premotor cortex (PMC) is functionally lateralized, such that the left PMC is activated for unimanual movements of either hand, whereas the right PMC is particularly active during complex bimanual movements. Here we ask the question whether the high activation of right PMC in the bimanual context reflects either hemispheric specialization or handedness. Left- and right-handed subjects performed a bimanual antiphase tapping task at different frequencies while transcranial magnetic stimulation (TMS) was used to temporarily disrupt left versus right PMC during complex bimanual movements.

A 24-week, randomized, treat-to-target trial comparing initiation of insulin glargine once-daily with insulin detemir twice-daily in patients with type 2 diabetes inadequately controlled on oral glucose-lowering drugs.

Objective: To determine whether glargine is noninferior to detemir regarding the percentage of patients reaching A1C <7% without symptomatic hypoglycemia
Research Design And Methods: In this 24-week trial, 973 insulin-naive type 2 diabetic patients on stable oral glucose-lowering drugs with A1C 7.

Brain-behavior relationships in young traumatic brain injury patients: fractional anisotropy measures are highly correlated with dynamic visuomotor tracking performance.

Traumatic brain injury (TBI) patients have a high incidence of eye-hand coordination deficits. Diffuse axonal injury is common in TBI and is presumed to contribute to persistent motor problems. Using Diffusion Tensor Imaging (DTI), this study sought to identify changes in (sensori)motor white matter (WM) pathways/regions in a TBI group during the chronic recovery stage.

Motor learning in Parkinson's disease: limitations and potential for rehabilitation.

The striatum is very much involved in learning motor sequences particularly in the consolidation phase, predicting that motor learning is affected in Parkinson's disease (PD). We conducted a literature review on this question and showed that behavioural studies indicate a relatively preserved acquisition as well as retention of motor learning in PD. Persons with PD did demonstrate slower learning-rates than controls.

The neural control of bimanual movements in the elderly: Brain regions exhibiting age-related increases in activity, frequency-induced neural modulation, and task-specific compensatory recruitment.

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.

Reduced basal ganglia function when elderly switch between coordinated movement patterns.

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.