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Richard Born, M.D.

Professor of Neurobiology
Harvard Medical School
Dept Neurobiology, WAB 215A
200 Longwood Ave
Boston, MA 02115
Telephone: 617 - 432-1307
Fax:(617) 734-7557
Email: richard_born@hms.harvard.edu
Website: The Born Lab
Predocs: 3 Postdocs: 2 Completed PhD's: 1

 Richard Born

Our lab is interested in the neural circuitry of the primate visual cortex and how it relates to perception and visually guided behavior. Our current focus is on areas of the brain that make calculations about visual motion. In what direction is it moving? How fast? Is it really moving with respect to its surroundings, or does it just seem to be moving because I'm moving? The calculations that allow an animal to answer these critical questions are performed by populations of neurons which are anatomically organized to form a map representing all possible directions of motion in all parts of the visual field. Superimposed on this map is a coarser organization of neurons whose receptive fields have differing center-surround interactions with respect to moving stimuli. This organization consists of slab-like clusters of cells whose receptive fields have motion opponent surrounds and thus signal local motion contrast interdigitated with clusters of cells whose receptive fields have additive surrounds and thus respond best to wide-field motion ( Born & Tootell 1992; Born 2000) The neurons within these two compartments make segregated connections to higher motion processing areas ( Berezovskii and Born 2000). We believe that these neurons are performing calculations necessary for distinguishing self- from object-motion. If we electrically activate a direction column within an interband while an animal is visually tracking a moving target, the smooth pursuit eye movements are sped up in the preferred direction of the neurons we're stimulating. If, on the other hand, we stimulate a direction column of wide-field neurons, the pursuit is sped up in the opposite direction­precisely the effect that one gets if the visual background moves in the preferred direction, which causes the target to appear as if it's moving in the opposite direction (so-called "induced motion; Born et al. 2000).

A second major focus of the lab concerns the integration of visual motion signals. Given that MT neurons appear to perform some of the calculations necessary to distinguish and object from the visual background, we might ask how different local motion signals emanating from the same object are combined to form an accurate representation of object motion. You can read a brief summary of this work here.  For a more detailed treatment of motion integration see Born & Bradley 2005.

Techniques: We use combinations of extracellular electrophysiology, 2-deoxyglucose mapping and anatomical tracing in order to learn the nature of the neural circuitry and the sorts of calculations that it makes. This allows us to make predictions about what that circuit is doing for the animal--predictions which we can test by activating parts of the circuits electrically or inactivating them by cooling in order to assess their role in behavior. If we have formulated our theories correctly, we should be able to perturb the behavior in specific and interesting ways.

Selected References:

  • Born RT (2004) Taking strategies to task. Neuron, 42:185-187.
  • Pack CC, Gartland AJ and Born RT (2004) Integration of contour and terminator signals in visual area MT of alert macaque. J. Neurosci., 24:3268-3280.
  • Born RT and Bradley DC (2005) Structure and function of visual area MT. Annu. Rev. Neurosci., 28:157-89. DOI, 10.1146/annurev.neuro.26.041002.131052
  • Pack, C. C., Hunter, J. N. and Born, R. T. (2005) Contrast dependence of suppressive influences in cortical area MT of alert macaque. J. Neurophysiol., 93:1809-1815.
  • Pack CC, Conway BR, Born RT and Livingstone MS (2006) Spatiotemporal structure of nonlinear subunits in macaque visual cortex. J. Neurosci., 26:893-907.
  • Born RT, Pack CC, Ponce CR and Yi Si (2006) Temporal evolution of 2-dimensional direction signals used to guide eye movements. J. Neurophsyiol., 95:284-300. DOI, 10.1152/jn.01329.2004
  • Dauguet JC, Peled S, Berezovskii VK, Delzescaux T, Warfield SK, Born RT and Westin CF (2007) Comparison of fiber tracts derived from in-vivo DTI tractography with 3D histological neural tract tracer reconstruction on a macaque brain. NeuroImage, in press.
  • Price NSC and Born RT (2007) Representation of movement. Encyclopedia of Neuroscience (Oxford: Elsevier Ltd.), in press.