Georgopoulos, Apostolos P., M.D.

BRAIN SCIENCES

The long-term goal of the research in our laboratory is to elucidate the neural mechanisms underlying cognitive processes in motor behavior and to understand the intrinsic mechanisms of the cerebral cortex. Experimental psychological studies, neurophysiological recordings, functional magnetic resonance imaging (MRI) at high field (4 and 7 Tesla), magneto-encephalography (MEG), and neural network modeling (using supercomputers) are pursued to achieve these goals. Psychological studies are carried out in both human subjects and rhesus monkeys. The tasks are cognitive-motor in nature and are currently focused on paradigms of mental rotation, memory scanning, and visuomotor control of isometric force trajectories generated by the arm. The patterns of activation of brain areas during performance of these tasks are determined using functional MRI at high fields in human subjects. Electrophysiological recordings of the activity of single cells in various areas of the cerebral cortex are then performed in behaving monkeys in order to elucidate the brain mechanisms involved in these tasks. This experimental arrangement provides for a direct study of the relations between neuronal populations and behavior. Aspects of integrated activity of these populations are then investigated in human subjects using a state-of-the-art, whole-head MEG instrument with 248 sensors. Finally, the activity of neuronal populations in a variety of motor and cognitive tasks is modeled using a massively interconnected neural network to produce dynamically evolving behaviors.