John Maunsell, Ph.D.

Investigator, Howard Hughes Medical Institute, Professor of Neurobiology

Harvard Medical School
220 Longwood Avenue
Boston, MA 02115
Telephone: 617-432-6779
Fax: 617- 432-6791
Email: maunsell@hms.harvard.edu
Predocs: 1 Postdocs: 1 Completed PhD's: 6

Our research is directed at understanding how neuronal signals in visual cerebral cortex generate perceptions and guide behavior. Our approach is to record from individual neurons in trained, behaving monkeys while they perform visual tasks. One line of our research is examining how paying attention to specific visual targets affects the way that they are represented in the brain, and how changes in the sensory representation caused by attention relate to changes in perception and behavior. Recent experiments have shown that attention increases the strength of neuronal responses without changing their selectivity, effectively representing the attended stimulus as if it were more intense than itreally is. Paired measurements of neuronal responses and behavioral performance have shown that much of the behavioral advantage conferred by attention may be explained by this change it causes in the sensory representation, rather than decision processes. Another line of research has been exploring the more general question of how the activity of given neurons contributes to specific visual behaviors. Measurements of the trial-to-trial correlation between the strength of a neuron's responses to a weak stimulus and the animal's performance detecting that stimulus have shown that different neurons contribute to a greater or lesser degree to particular behaviors depending on which stimuli they are most sensitive to. With these and other approaches we hope to provide a more complete understanding of how individual neurons contribute to specific visual perceptions and behaviors.

References:

• Yang, T., Maunsell, J.H.R. (2004) The effect of perceptual learning on neuronal responses in monkey visual area V4. Journal of Neuroscience 24:1617-1626.
• Cook, E.P., Maunsell, J.H.R. (2004) Attentional modulation of motion integration of individual neurons in the middle temporal area (MT). Journal of Neuroscience 24:7964-7977.
• Maunsell, J.H.R. (2004) Neuronal representations of cognitive state: reward or attention? Trends in Cognitive Science 8:261-265.
• Williford, T., Maunsell, J.H.R. (2006) Effects of spatial attention on contrast response functions in macaque area V4. Journal of Neurophysiology 96:40-54.
• Maunsell, J.H.R., Treue, S. (2006) Feature-based attention in visual cortex. Trends in Neuroscience 29:317-322.