We pick up objects and manipulate them with our fingers hundreds of times each day. Our brain must integrate information about the target object and feedback from the arm and hand into movements. 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?
Our present focus is on the organization of primary motor cortex (M1) – critical node in the parietal-frontal network – of macaque monkeys and squirrel monkeys. We are tackling these questions using a combination of intrinsic signal optical imaging, single-unit recording, optogenetics, and microstimulation. In one project, we are investigating the spatio-temporal organization of neural activity that encodes reaching and grasping in awake/behaving monkeys. In a parallel project, we are investigating the point-to-point connectivity of the entire forelimb representation in M1. The collective goal of our projects is to reveal the organizational principles that confer on M1 the capacity to control coordinated arm/hand movements in primates.
Qi HX, Reed JL, Gharbawie OA, Kaas JH (2014) Cortical neuron response properties are related to lesion extent and behavioral recovery after sensory loss from spinal cord injury in monkeys. Journal of Neuroscience, 34(12):4345-63.
Stepniewska I, Gharbawie OA, Burish MJ, Kaas JH (2014) Effects of muscimol inactivations of functional domains in posterior parietal, premotor and motor cortex on complex movements evoked by electrical stimulation.Journal of Neurophysiology, 111(5):1100-19.
Gharbawie OA, Stepniewska I, Kaas JH (2011) Cortical connections of functional zones in posterior parietal cortex and frontal cortex motor regions in New World monkeys. Cerebral Cortex, 21(9):1981-2002.