Neurobiology

David H. Hubel, M.D.

John Enders University Professor of Neurobiology, Emeritus

Hubel Lab Website: http://neuro.med.harvard.edu/site/dh/index.html

I am interested in learning how the activation of brain cells is related to an animal's environment and behavior. I work with higher animals (at present almost exclusively macaque and squirrel monkeys, and I study the parts of the visual cortex called the primary visual cortex (V-1) and V-2. In the past, our experiments have been done in anesthetized animals, but we have in recent years changed over to single-cell recordings in awake, alert, freely viewing monkeys. We study all aspects of vision: form, color, movement, and stereoscopic depth. For each cell recorded we try to determine the optimal visual stimulus. In V-1 (striate cortex), for example, the great majority of cells require a line segment in an orientation specific for the cell; about one-tenth require that the line be of limited length; some cells have special requirements for color or movement direction or depth plane. Much of our past work has been devoted to correlating the response requirements with cortical anatomy, especially columns perpendicular to the cortical layers. Cells of like orientation are grouped into orientation columns, cells with like ocular dominance into ocular dominance columns, and so on. Our work has thus been about two-thirds physiological recording and one-third experimental anatomy. Past research  involved studies of the postnatal development of the visual cortex and the possibility of perturbing the system, its anatomy and physiology, during a critical period in the first months of the life of a cat or monkey. The chief methods of deprivation were eyelid suture, and strabismus produced by cutting one or more eye muscles. Such procedures turn out to work only in the first six months or so, and they exert their effects on the visual path at the level of V-1 or beyond.

SOURCES: 1, Hubel DH (1995) Eye, Brain and Vision. Scientific American Library, No. 22., WH Freeman, NY. p. 70. 2 Hubel DH and Wiesel TN (2005) Brain and Visual Perception. Oxford University Press.