Jean-Pierre Changeux (; born 6 April 1936) is a French neuroscientist known for his research in several fields of biology, from the structure and function of proteins (with a focus on the allosteric proteins), to the early development of the nervous system up to cognitive functions. Although being famous in biological sciences for the MWC model, the identification and purification of the nicotinic acetylcholine receptor and the theory of epigenesis by synapse selection are also notable scientific achievements. Changeux is known by the non-scientific public for his ideas regarding the connection between mind and physical brain. As put forth in his book, Conversations on Mind, Matter and Mathematics, Changeux strongly supports the view that the nervous system functions in a projective rather than reactive style and that interaction with the environment, rather than being instructive, results in the selection amongst a diversity of preexisting internal representations.
Biography
Changeux was born in Domont, France to Marcel Changeux and Jeanne Benoît. He entered the École Normale Supérieure in 1955, where he obtained a bachelor's degree (Licence) in 1957 and a master's degree (Diplome d'Études Supérieure) in 1958. He also received his agrégation in natural science the same year. He began his scientific career during his ENS years during summer internships in Banyuls-sur-Mer where he identified a new genus of parasitic Copepod. He pursued PhD studies at the Pasteur Institute under the direction of Jacques Monod and François Jacob, and gained his doctorate in 1964. Changeux then left France for postdoctoral studies first at the University of California Berkeley (1965–1966) then at Columbia University College of Physicians and Surgeons, New-York (1967). He returned to France as attaché to the chair of Molecular Biology held by Jacques Monod. In 1972, he became director of the Unit of Molecular Neurobiology at the Pasteur Institute, where he received a professorship in 1975. In 1975, Changeux was elected professor at the Collège de France, chair of Cell Communications, position that he held until 2006. Changeux is author of more than 600 scientific articles and several books, technical or for general audience.
Scientific achievements
All his scientific career, Changeux has been faithful to a handful of scientific questions, at molecular, cellular and brain levels. If one needs to seek a unifying theme to all of them, it is the conviction that selection is the basis of life processes, rather than instruction. While started as separate lines of investigations, all the research threads were tied in the recent decades within the study of allosteric mechanisms as a basis of for the involvement of nicotinic receptors in cognitive functions.
Allostery
During his PhD studies in the laboratory of Jacques Monod and François Jacob, Changeux studied the allosteric regulations of enzymes, that is the modulation of their activity by compounds different from their substrates. This work led to the development of the model of concerted transitions for allosteric proteins. The main ideas behind this theory are: 1) proteins can exist under various conformations in thermal equilibrium in the absence of regulators. The allosteric regulators merely shift the equilibrium between the conformations, stabilizing the ones for which they display the highest affinity, and 2) all the subunits of a symmetrical multimeric protein exist in the same conformation, the transition taking place in a concerted fashion. The resulting model explains the observed cooperativity without a progressive change of biophysical parameters. This conceptual framework is still the principal model used to explain the function of cooperative proteins such as hemoglobin.