John Assad

Department of Neurobiology
Harvard Medical School
Warren Alpert Building, Room 222
200 Longwood Avenue
Boston, MA 02115

Telephone: 617 432-2804; fax: 617 734-7557

Research Interests:

The goal of my lab’s research is to understand how the primate brain controls behavior by integrating external sensory information with internal states, such as attention or motivation. The brain has an astonishing ability to flexibly link sensation and action. The same visual object may trigger different actions depending on external context or the animal’s internal needs, preferences or state of attention.

My lab uses electrophysiological techniques to study the brain computations between sensory input and motor output. We have focused on three important aspects of this processing chain:
1) how visual information is transformed into a behaviorally useful form,
2) how appropriate movements are initiated at precise times, and
3) how the value of objects or goals in the environment is assigned to guide behavior.

For many of these studies, my lab has focused on the parietal cortex, a part of the brain that acts as a bridge between sensation and action. We have also examined the role of the basal ganglia in movement control, an issue that is relevant for understanding movement disorders such as Parkinson’s disease, and we have studied the orbitofrontal cortex in the context of how the brain represents value.

Why do we do things exactly when we do? What “goes off” in our brains to trigger movements at precise times? Answers to these questions are central to understanding the neural mechanisms of movement control, and may shed light on movement disorders such as Parkinson’s and Huntington’s disease.

Selected Publications:

Herrington, T.M., Masse, N.Y., Hachmeh, K.J., Smith, J.E.T., Assad, J.A. and Cook, E.P.  (2009)  The effect of microsaccades on the correlation between neural activity and behavior in areas MT, VIP and LIP.  J. Neurosci. 29:5793-5805.

Maimon, G. and Assad, J.A.  (2009) Beyond Poisson: increased spike-time regularity across primate parietal cortex.  Neuron 62(3):426-40.

Freedman, D.J. and Assad, J.A.  (2009)  Distinct encoding of spatial and non-spatial information in parietal cortex. J. Neurosci. 29:5671-5680.

Padoa-Schioppa, C. and Assad, J.A.  (2008)  The representation of economic value in the orbitofrontal cortex is invariant for changes of menu. Nat. Neurosci. 11:95-102.

Fanini, A. and Assad, J.A. (2008)  Direction selectivity of neurons in the macaque lateral intraparietal area. J. Neurophys. 101:289-305.

Freedman, D.J. and Assad, J.A. (2006)  Experience-dependent representation of visual categories in parietal cortex. Nature 443:85-88.

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