MIT Reports to the President 1994-95

Department of Brain and Cognitive Sciences


Research in the Department of Brain and Cognitive Sciences continues to span a broad range of questions and approaches. The main areas of research include molecular and cellular neuroscience, systems neuroscience, computation, and cognitive science.

Molecular And Cellular Neuroscience

Professor Ann Graybiel's laboratory, in collaboration with Professsor Susumu Tonegawa, has shown that in mice lacking the gene for a subtype of dopamine receptor, there is a remarkable loss of dynorphin expression in the basal ganglia. These findings have relevance for the diagnosis and treatment of movement disorders that involve the basal ganglia, such as Parkinson's Disease, in which the neurotransmitter dopamine is specifically implicated.

Recent findings in Professor Gerald Schneider's laboratory challenge the dominant theory explaining the failure of axonal regeneration after injury in the adult mammalian brain. These findings suggest that programmed changes in the neuronal cells of origin, rather than negative influences in the tissue environment, are the major cause of decline in regenerative ability of axons in the central nervous system. This research has significance for understanding mechanisms of brain repair after injury or trauma.

Professor William Quinn's laboratory has characterized a peptide transmitter with an evident role in middle term memory. Antibodies generated to this peptide have led to the functional localization in the Drosophila brain of cells producing the peptide. The antibodies may also facilitate the search for mammalian versions of the peptide, with implications for human memory and learning.

Professor Richard Wurtman's lab has discovered that glutamate, a brain neurotransmitter which is especially abundant in brain regions (like cortex and hippocampus) that are involved in memory and learning, and which is deficient in brains of people with Alzheimer's Disease, normally controls the metabolism of the brain protein APP. In the presence of normal glutamate levels, this protein is metabolized in a a way which does not lead to the formation of the amyloid plaques characteristic of Alzheimer's Disease. However in the absence of glutamate, APP is broken down to yield A-beta peptides, which can form amyloid. The glutamate acts via metabotropic glutamate receptors. These findings are important for understanding and possibly treating Alzheimer's Disease.

Systems Neuroscience

Professor Emilio Bizzi's laboratory has performed a series of psychophysical and physiological studies in humans and monkeys aimed at understanding motor learning. They have focused on two aspects of motor learning: generalization and consolidation. With respect to generalization, they have shown that learning to move the arm against disturbing forces is local to the region where training has occurred. This result implies that the computational elements that subserve learning resemble a look-up table. With respect to consolidation, they have shown that learning a second task interferes with the subject's retention of a newly learned motor skill. This interference is effective only during a few hours following the learning of the first task.

Professor Mriganka Sur's laboratory has used optical imaging techniques to record the activity of neuronal populations in visual cortex. The activity of cortical neurons can be regulated in dynamic fashion by long-range connections within cortex. This work provides an important basis for context-dependent effects in vision, and more generally, for the cortical processing of visual information.


Professor Tomaso Poggio, in collaboration with Dr. Federico Girosi in the Center for Biological and Computational Learning, has shown that regularization networks for learning encompass a very broad range of approximation schemes. The result is significant because it provides a unified theoretical framework for a spectrum of neural network architectures and statistical techniques.

Professor Edward Adelson has developed models for the analysis of transparent motion and motion segementation. This work has applications in modeling human vision as well as in computer vision and image coding.

Cognitive Science

Professor Steven Pinker, in collaboration with Professor Suzanne Corkin, has examined language ability in patients with neurological syndromes. They have confirmed a neural dissociation between grammatical computation and lexical lookup. Agrammatic aphasics and Parkinson's Disease patients have trouble converting 'walk' to 'walked' and 'wug' to 'wugged' and never make overgeneralization errors such as 'comed', whereas Anomic aphasics and Alzheimer's Disease patients have trouble converting 'come' to 'came', make errors such as 'comed', and have no trouble with 'walk-walked' or 'wug-wugged'. This points to a substrate for grammatical processing in a procedural system located in basal-ganglia/frontal-cortex circuits, and a substrate for lexical memory in a declarative memory system located in limbic/posterior-cortex circuits.

Professor Mary Potter's lab has focused on the deployment of attention when events occur rapidly in vision, audition, or both. Her lab demonstrated that a visual "attention blink" makes it difficult to encode the second of two visual targets among distractors, within a 50 ms window. Professor Potter has recently shown that no such attentional bottleneck arises with rapid auditory targets, and work on mixtures of auditory and visual targets is under way.



Applications to the Ph.D. program reached an all-time high this year, increasing to 224 from a previous high of 195. The quality of the applicants was also particularly impressive. In addition, the hiring of three new faculty members has permitted the expansion of course offerings into new areas: Biochemistry & Pharmacology of Synaptic Transmission, Neural Plasticity in Learning & Development, Neural Basis of Learning & Memory, Development & Neural Bases of Higher Cognitive Functions, and Statistical & Methodological Techniques.

Nine students complete the Ph.D. during the past year. One has accepted a faculty position at Yale, and the others have opted for postdoctoral fellowships.


The number of undergraduate majors has increased by 22%, continuing an upward trend of the past three years. New courses have been added, and the proposed major is neurosciences is anticipated to be in effect by the Spring 1996.


Suzanne Corkin was awarded the Smith College Medal.

Ann M. Graybiel was awarded the Walter A. Rosenblith Professorship in Neuroscience and elected to the Institute of Medicine of the National Academy of Sciences.

Steven Pinker won the William James Book Award of the American Psychological Association. The New York Times Book Review, London Times Book Review and Boston Globe Book Review chose The Language Instinct as one of the ten best books of 1994.

Matthew Wilson was named an Alfred P. Sloan Research Fellow and Edward J. Poitras Associate Professor of Human Biology and Experimental Medicine. He also received the Seaver Award.

Richard Wurtman was named Cecil B. Green Distinguished Professor.

Emilio Bizzi, M.D.

MIT Reports to the President 1994-95