The National Academy of Medicine announced Oct. 17 that its members have elected Mark Bear, Picower Professor of Neuroscience in The Picower Institute for Learning and Memory, to join their esteemed ranks.
Election to the Academy is considered one of the highest honors in the fields of health and medicine and recognizes individuals who have demonstrated outstanding professional achievement and commitment to service, the Academy noted in announcing the election of 100 new members including Bear.
Bear’s citation from the Academy reads: “For his discovery of fundamental mechanisms by which sensory experience and deprivation modify synapses by increasing or decreasing their strength during the development of the brain, and how these mechanisms contribute to, and can be marshalled to treat, developmental brain disorders.”
Synapses are the connections neurons make to form the circuits that enable brain functions including perception and cognition. During several decades of research, including the last 20 years at MIT, Bear’s lab has made key discoveries about the molecular means by which synapses dynamically change in response to experience, a capability known as “plasticity.” In 2006, for example, Bear and co-authors provided the first direct demonstration that a key strengthening mechanism, long-term potentiation, occurs during memory formation in the hippocampus region of the brain. In the 1990s, Bear’s Lab led the discovery that reduced sensory input weakens synaptic connections by a mechanism called long-term depression, or LTD.
Subsequent studies in Bear’s Lab have led to potential therapies for disorders related to LTD. One is the common vision disorder amblyopia, in which occlusion of an eye during childhood, for instance from a cataract, weakens connections in the brain serving that eye. Bear’s lab has shown in multiple animal models of amblyopia that temporarily anesthetizing the normal, or “fellow,” eye resets the threshold for synaptic plasticity, allowing incoming sensory input to strengthen rather than weaken synapses, even in adulthood when other treatments fail. The result is a recovery of vision in the weakened eye without any cost to the fellow eye.
Bear’s lab has also advanced potential therapies for autism spectrum disorders including Fragile X syndrome, in which the genetic loss of a protein called FMRP leads to too much LTD. His lab has discovered that intervening in the molecular mechanisms of LTD can have substantial therapeutic effects in mouse models and has shown promise in clinical trials. Bear has continued to work to develop therapies based on the discovery.
Bear said that the Academy’s recognition of these discoveries and achievements honors the many young scientists with whom he has worked in his lab over the years.
“I am delighted and grateful to have received this honor, which I accept on behalf of the many students and postdocs who have contributed to the science my laboratory is recognized for,” he said.
Bear joins Picower Institute colleagues Emery N. Brown, Mriganka Sur, and Li-Huei Tsai as National Academy of Medicine members. In addition to Bear, MIT Chemistry Professor Laura L. Kiessling earned election to the Academy this year.