No abstract

During bimanual load lifting, the brain must anticipate the effects of unloading upon the load-bearing arm. Little is currently known about the neural networks that coordinate these anticipatory postural adjustments. We measured neuromagnetic brain activity with whole-head magnetoencephalography while participants performed a bimanual load-lifting task. Anticipatory adjustments were associated with reduction in biceps brachii muscle activity of the load-bearing arm and pre-movement desynchronization of the cortical beta rhythm. Beamforming analyses localized anticipatory brain activity to the precentral gyrus, basal ganglia, supplementary motor area, and thalamus, contralateral to the load-bearing arm. To our knowledge this is the first human neuroimaging study to directly investigate anticipatory postural adjustments and to explicitly partition the anticipatory and volitional aspects of brain activity in bimanual load lifting. These data contribute to our understanding of the neural systems supporting anticipatory postural adjustments in healthy adults.

Even the simplest volitional movements must be precisely coordinated with anticipatory postural adjustments. Little is currently known about the neural networks that coordinate these adjustments in healthy adults. We measured brain activity prior to movement during a bimanual load-lifting task, designed to elicit anticipatory adjustments in a restricted and well-defined set of musculature in the arm. Electroencephalography and magnetoencephalography brain measurements were obtained from eleven participants while they performed a bimanual load-lifting task that required precise inter-limb coordination. Anticipatory biceps brachii inhibition in the loaded arm was associated with a robust desynchronization of the beta rhythm. Beamforming analyses localized beta band responses to the parietal lobules, pre- and post-central gyri, middle and medial frontal gyri, basal ganglia and thalamus. The current study shows that premovement brain activity in a bimanual load-lifting task can be imaged with magnetoencephalography. Future experiments will partition out brain activity associated with anticipatory postural adjustments and volitional movements. The experimental paradigm will also be useful in the study of motor function in patients with developmental or degenerative disorders.