Coordination of limb movements requires continuous interactions between cortical neurons in separate regions representing different components of the movements. The neural mechanisms mediating these interactions remain unknown. A testable hypothesis proposes that intracortical """"""""binding"""""""" may be mediated by some form of temporal synchrony between the firing of neurons, in the form of either coincidences between aperiodic cell spikes or periodic oscillatory activity. Our previous studies have documented the appearance of widespread oscillatory activity in sensorimotor cortex during finely controlled reaching movements. To investigate these mechanisms further, we documented the activity of arm-related neurons in left and right motor cortex in two pigtailed macaques while they performed a coordinated bimanual task. The monkeys controlled the two-dimensional position of a cursor on a video screen by operating two joysticks separately with the left and right hands. Each joystick controlled one axis of the cursor position (x or y position). Both monkeys performed well in tracking a randomly moving target. In addition to cell activity we recorded local field potentials in premotor and supplementary motor areas; these field potentials provide robust measures of synchronous activity in local populations. Sometimes the relation between the joystick deflection and cursor coordinates was altered unexpectedly so that we could analyze the neural concomitants of learning new motor strategies. The recordings are being analyzed to determine whether synchrony is increased preferentially during the coordinated task, and when this synchrony occurs with respect to changes in target position. The results will elucidate the long-range cortical interactions that mediate coordinated sensorimotor activity.
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