Organization of the parietal-frontal network that controls reaching and grasping.
We pick up objects and manipulate them with our fingers hundreds of times each day. Central nervous system injuries and neurological diseases can devastate these crucial motor skills. Compromises in quality of life and economic consequences have motivated considerable investments into developing solutions to restoring hand use, particularly for prehension. Advances in this goal hinge on determining how the brain controls manual movements and integrates sensory information into those actions. Evidence from converging lines of research in human and non-human primates shows that a parietal-frontal network is critical to the sensorimotor transformations necessary for the formulation and execution of a prehension plan. However, important questions about the organization of this parietal-frontal network remain outstanding. (1) What are the organizing principles of the network that confer on it the capacity of producing different grip postures (e.g. precision and whole-hand grip)? (2) What is the point-to-point connectivity of each of the network nodes?
My laboratory tackles those questions through two parallel lines of research. The main goal in one stream is to determine how neuronal populations in frontal and parietal cortex encode the arm and hand movements necessary for grasping. A related goal involves understanding how the same neuronal populations incorporate haptic feedback from the hand and visual feedback from the target object into an action plan. To achieve this goal, optical imaging and neurophysiological techniques are used to study the frontal and parietal cortex of monkeys as they perform a grasping task. The main goal of the second line of research is to determine the organization of the connections that link neuronal populations in frontal cortex with their counterpart in parietal cortex. This line of work is pursued primarily in anesthetized animals using optical imaging, neurophysiology, and anatomical methods.
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Liao, C.C., Gharbawie, O.A., Qi, H.X. and Kaas, J.H. Cortical connections to single digit representations in area 3b of somatosensory cortex in squirrel monkeys and prosimian galagos. J Comp Neurol, 521(16): 3768-90, 2013.
Gharbawie, O.A., Stepniewska, I., Qi, H.X. and Kaas, J.H. Multiple parietal-frontal networks mediate grasping in macaque monkeys. Journal of Neuroscience, 31(32): 11660-77, 2011.
Gharbawie, O.A., Stepniewska, I. and Kaas, J.H. Cortical connections of functional zones in posterior parietal cortex and frontal cortex motor regions in New World monkeys. Cerebral Cortex 21(9): 1981-2002, 2011.
Stepniewska, I., Friedman, R.M., Gharbawie, O.A., Cerkevich, C.M., Roe, A.W. and Kaas, J.H. Activation patterns in motor cortex revealed by optical imaging during intracortical microstimulation of posterior parietal cortical sites that evoke complex movements. PNAS, 108(37): E725-32, 2011.