Research Interests

One of the fundamental problems in systems neuroscience today is to understand how the activation of large populations of neurons gives rise to some of the most interesting functions of the brain, such as perception, action, learning, memory, cognition and ultimately conscious awareness. Over the past forty years, electrophysiological recordings in behaving animals have revealed considerable information about the firing patterns of single neurons in isolation, but it remains a mystery how large collections of interacting neurons mediate these functions. My overall research program is to understand how neuronal ensembles in the cortex act together to control, coordinate, and learn complex movements of the arm and hand. Using multi-electrode technology to simultaneously record from large groups of neurons, we are in a unique position to examine the activity of multiple single units in various motor cortical areas to attempt to answer two fundamental questions:

1) what motor features are encoded in single motor cortical neurons as well as in motor cortical ensembles, and

2) how these features are encoded in motor cortical ensembles.

In addition to advancing our basic understanding of the brain, this research program is contributing to a more applied research project to develop neural prosthetic systems (or brain-machine interfaces) for paralyzed patients. Our system records electrical signals from the motor cortex, decodes them into a set of behaviorally relevant output signals, and then uses these output signals to drive a computer cursor or robotic device. We are currently developing novel decoding algorithms and augmenting existing brain-machine interface systems with different forms of sensory feedback.

Selected Publications

Tkach, D., Reimer, J., & Hatsopoulos, N.G. (in press). Congruent activity during action and action observation in motor cortex, Journal of Neuroscience.

Fagg, A.H., Hatsopoulos, N.G., de Lafuente, V., Moxon, K.A., Nemati, S., Rebesco, J.M., Romo, R., Solla, S.A., Reimer, J., Tkach, D., Pohlmeyer, E.A., & Miller, L.E. (2007). Biomimetic brain machine interfaces for the control of movement. Journal of Neuroscience, 27, 11842-11846. (PubMed)

Hatsopoulos, N.G., Xu, Q., Amit, Y. (2007). Encoding of movement fragments in the motor cortex. Journal of Neuroscience, 27, 5105-5114. (PubMed)

Wu, W. and Hatsopoulos, N.G. (2007). Coordinate system representations of movement direction in the premotor cortex. Experimental Brain Research, 176, 652-657. (PubMed)

Rubino, D., Robbins, K.A., Hatsopoulos, N.G. (2006). Propagating waves mediate information transfer in the motor cortex. Nature Neuroscience, 9, 1549-1557. (PubMed)

Wu, W. and Hatsopoulos, N.G. (2006). Evidence against a single coordinate system representation in the motor cortex. Experimental Brain Research, 175,197-210. (PubMed)

O’Leary, J.G. and Hatsopoulos, N.G. (2006). Early visuomotor representations revealed from evoked local field potentials in motor and premotor cortical ensembles. Journal of Neurophysiology, 9, 1492-1506. (PubMed)

Hatsopoulos, N.G., Joshi, J., O’Leary, J.G. (2004). Decoding continuous and discrete motor behavior from motor and premotor cortical ensembles. Journal of Neurophysiology, 92, 1165-1174. (PubMed)

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