The role of the basal ganglia in bimanual coordination.
ABSTRACT The functional anatomical role of the basal ganglia in bimanual coordination is unknown. Utilizing functional MRI (fMRI) at 3 T, we analyzed brain activity during three different typing tasks. The first task consisted of typing with parallel finger movements (moving left to right with four fingers on both hands). The second task was mirror movements (moving little finger to index finger on both hands), and the third task compared a resting condition with right-handed unimanual typing (moving little finger to index finger). Task dependent BOLD activity in the supplementary motor area (SMA) and dorsolateral premotor areas was observed. In addition, activation patterns were present in the cerebellar vermis during bimanual coordination tasks, with greater activation in the parallel than in the mirror condition. Finally, we also identified activity in the putamen during the tasks described above. Interestingly, putaminal activity was greatest during the period of motor task initiation, and activity during this period was greatest in the parallel condition. Our results suggest a critical role of the basal ganglia in the neural control of bimanual coordination.
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ABSTRACT: Any motor action results from a dynamic interplay of various brain regions involved in different aspects of movement preparation and execution. Establishing a reliable model of how these areas interact is crucial for a better understanding of the mechanisms underlying motor function in both healthy subjects and patients. We used fMRI and dynamic causal modeling to reveal the specific excitatory and inhibitory influences within the human motor system for the generation of voluntary hand movements. We found an intrinsic balance of excitatory and inhibitory couplings among core motor regions within and across hemispheres. Neural coupling within this network was specifically modulated upon uni- and bimanual movements. During unimanual movements, connectivity towards the contralateral primary motor cortex was enhanced while neural coupling towards ipsilateral motor areas was reduced by both transcallosal inhibition and top-down modulation. Bimanual hand movements were associated with a symmetric facilitation of neural activity mediated by both increased intrahemispheric connectivity and enhanced transcallosal coupling of SMA and M1. The data suggest that especially the supplementary motor area represents a key structure promoting or suppressing activity in the cortical motor network driving uni- and bilateral hand movements. Our data demonstrate that fMRI in combination with DCM allows insights into intrinsic properties of the human motor system and task-dependent modulations thereof.NeuroImage 08/2008; 41(4):1382-94. DOI:10.1016/j.neuroimage.2008.03.048 · 6.13 Impact Factor
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ABSTRACT: IntroductionStenography, or shorthand, is a unique set of skills that involves intensive training which is nearly life-long and orchestrating various brain functional modules, including auditory, linguistic, cognitive, mnemonic, and motor. Stenography provides cognitive neuroscientists with a unique opportunity to investigate the neural mechanisms underlying the neural plasticity that enables such a high degree of expertise. However, shorthand is quickly being replaced with voice recognition technology. We took this nearly final opportunity to scan the brains of the last alive shorthand experts of the Japanese language.Methods Thirteen right-handed stenographers and fourteen right-handed controls participated in the functional magnetic resonance imaging (fMRI) study.ResultsThe fMRI data revealed plastic reorganization of the neural circuits around the putamen. The acquisition of expert skills was accompanied by structural and functional changes in the area. The posterior putamen is known as the execution center of acquired sensorimotor skills. Compared to nonexperts, the posterior putamen in stenographers had high covariation with the cerebellum and midbrain.The stenographers' brain developed different neural circuits from those of the nonexpert brain.Conclusions The current data illustrate the vigorous plasticity in the putamen and in its connectivity to other relevant areas in the expert brain. This is a case of vigorous neural plastic reorganization in response to massive overtraining, which is rare especially considering that it occurred in adulthood.03/2015; 5(5). DOI:10.1002/brb3.333
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ABSTRACT: Due to basal ganglia dysfunction, bimanual motor performance in Parkinson patients reportedly relies on compensatory brain activation in premotor-parietal-cerebellar circuitries. A subgroup of PD patients with freezing of gait (FOG), may exhibit greater bimanual impairments up to the point that motor blocks occur. This study investigated the neural mechanisms of upper limb motor blocks and explored their relation with FOG. Brain activation was measured using fMRI during bilateral finger movements in 16 PD with FOG, 16 without FOG (PD+FOG; PD-FOG) and 16 controls. During successful movement, PD+FOG showed decreased activation in right dorsolateral prefrontal cortex (PFC), left dorsal premotor area (PMd) and left M1 and bilaterally increased activation in dorsal putamen, pallidum and STN compared to PD-FOG and controls. Contrary, upper limb motor blocks were associated with increased activation in right M1, PMd, SMA, and left PFC compared to successful movement, whereas bilateral pallidum and putamen activity was decreased. Complex striatofrontal activation changes may be involved in the difficulties of PD+FOG to perform bimanual movements, or sequential movements in general. These novel results suggest that, whatever the exact underlying cause, PD+FOG seem to have reached a saturation point of normal neural compensation and respond belatedly to actual movement breakdown.Cerebral Cortex 01/2013; · 8.31 Impact Factor