Heads of Laboratories
George N. Reeke Jr., Ph.D.
Laboratory of Biological Modeling
Chemical and electrical signals exchanged between cells can influence their growth, differentiation and interactions with other cells, giving rise to complex systems whose behavior is not easy to predict. Using computer simulations, Dr. Reeke’s research is concerned with how the multiple components of biological systems work together to carry out complex functions, and with using those simulations to predict outcomes in different situations.
By developing computer models of whole neuronal systems, which are the biological substrates for behavior and higher thought processes, Dr. Reeke seeks a greater understanding of how physical phenomena in the nervous system give rise to mental phenomena at the psychological level and behavior.
As the nervous system develops, it must acquire adaptive behavior through interactions with the environment. Dr. Reeke’s research simulates neural systems based on experimental neurophysiology with simulated or real sensors and locomotor organs and then challenges those systems to perform various tasks, shedding light on sensory integration, perceptual categorization, motor control and aspects of memory in normal and damaged or diseased brains. The models have shown how the ability to recognize objects and events in the environment can arise in the nervous system as a result of the operation of selective processes guided by innate value systems. Dr. Reeke’s research indicates that there is no need for built-in representational codes or computational algorithms, nor for feedback of error signals from omniscient external teachers. The results call into question the popular theory that the brain is a kind of computer.
Areas of particular interest in Dr. Reeke’s lab are perception and control of locomotion and the development of analytic tools appropriate for the characterization of these activities in space and time. He is focusing on neural mechanisms for the recognition and recall of temporal patterns, which are of fundamental importance for planning and navigation, language and music. The lab has developed novel information-theoretic measures, based on the temporal intervals between events of interest, that will help to quantitate the temporal characteristics of the signals exchanged among neurons and the spatiotemporal discharge activity of neuronal assemblies.
Dr. Reeke has shown that these same measures can be used to analyze data obtained from behavioral experiments with animals. In a collaborative project with Rockefeller’s Donald W. Pfaff, Dr. Reeke helped measure the contribution of estrogens to exploratory behavior in female mice. The method could also be adapted to measure the contribution of a range of genes to behavior as well as to understand the effect of different genotypes or pharmacological manipulations on behavior.
Dr. Reeke’s lab has also developed a composite approach to modeling neurons, in which the degree of detail employed in modeling different membrane conductances is adapted to the dynamical complexity of each neuron. For example, analysis of a model cerebellar Purkinje cell shows that when both the rate and the timing of a stimulus are varied, novel cell discharge behavior emerges. Studies of large-scale systems incorporating these data provide a greater understanding of how different types of neurons in both normal and diseased brains function at the integrated system level. These methods have been applied by members of the lab to study nonclassical responses of cells in the primary visual cortex, the process by which juvenile birds learn their songs, how general anesthetics affect the activities of neuronal clusters in the cerebral cortex, and the generation of descriptive models of sensorimotor contingencies and their relationship to reward in the cerebellum and other brain regions.
Dr. Reeke received his undergraduate degree in chemistry from the California Institute of Technology in 1964. He then moved to Harvard University, where he trained as a protein crystallographer, completing his M.A. in chemistry in 1966 and his Ph.D. in physical chemistry in 1969. After a one-year postdoc at Harvard, Dr. Reeke moved to Rockefeller as assistant professor in 1970, becoming associate professor in 1976 and associate professor with tenure in 1987.
Dr. Reeke received a National Science Foundation Predoctoral Fellowship and from 1975 to 1979 was an Alfred P. Sloan Research Fellow. He is a member of the Society for Neuroscience, the International Neural Network Society, the Harvey Society and Sigma Xi. He is also a member of the editorial board of the Journal of Integrative Neuroscience.
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