This project integrates neurophysiological research into the visual and somatosensory mechanisms that govern planning of skilled motor behaviors of the hand with development and distribution of neuroinformatics tools useful for data visualization, analysis and manipulation required for such studies.
Aim 1 establishes a Neuroinformatics Resource to distribute integrated tools enabling quantitative analyses of spike trains obtained with digital video (DV), and their correlation to the kinematics of hand actions. Interactive tools will be provided over the Internet for 1) spike recognition and separation, 2) event- linked rasters and PSTHs, 3) continuous firing rate graphs, and 4) metrics of spike synchrony. An international network of neuroscientists studying primate hand function will evaluate the tools, and provide research synergies from diverse studies of hand function. The tools are used in Aims 2 and 3 to assess the contribution of visual and haptic information about object size, shape and location in motor planning of acquisition and manipulation by the hand. Spike trains recorded in posterior parietal cortex (PPC) from single neurons, and from neuronal assemblies studied with multielectrode arrays, are synchronized to simultaneously acquired images of hand kinematics with DV. We postulate that skilled hand behaviors require the registration and coordination of an external map that locates an object's spatial coordinates and encodes its intrinsic geometry, and an internal map of the body's own image that represents the hand posture and dynamics. Protocols comparing shape and location-dependent cues distinguish intention-related activity planning grasping behaviors, from sensory responses to views of objects and hand-object interactions during performance of a trained grasp-and-lift task.
Aim 2 analyzes firing patterns obtained when objects can be viewed, and when an opaque barrier, requiring the use of memory, blocks vision and haptic cues for object acquisition and manipulation.
Aim 3 measures the integration of vision and touch during tool use when grasped objects are inserted into matching slots to illuminate a target. These experiments test hypotheses that synchronization and/or coherence of firing between PPC regions dominated by vision and touch enable a match-to-sample mode of sensorimotor control and error correction that enables efficient, adaptive behaviors. This research has important clinical implications for understanding dysmetrias, optic ataxias, grasp abnormalities and neglect syndromes resulting from neurological damage to PPC, and provides basic insights into mechanisms of visuomotor control of the hand that may prove useful for rehabilitation after stroke or injury.
