Science commentary]Scientists have long believed that the central amygdala, a structure located deep within the brain, is linked with fear and responses to unpleasant events. However, a team of MIT neuroscientists has now discovered a circuit in this structure that responds to rewarding events. In a study of mice, activating this circuit with certain stimuli made the animals seek those stimuli further. The researchers also found a circuit that controls responses to fearful events, but most of the neurons in the central amygdala are involved in the reward circuit, they report. “It’s surprising that positive-behavior-promoting subsets are so abundant, which is contrary to what many people in the field have been thinking,” says Susumu Tonegawa, Ph.D., the Picower Professor of Biology and Neuroscience and director of the RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory. Dr. Tonegawa, who won the Nobel Prize for Physiology or Medicine in 1987 for his discovery of the genetic mechanism that produces antibody diversity is the senior author of the study, which appears in the March 22, 2017 issue of Neuron. The paper’s lead authors are graduate students Joshua Kim and Xiangyu Zhang. The article is titled “Basolateral to Central Amygdala Neural Circuits for Appetitive Behaviors.” The paper builds on a study published last year in which Tonegawa’s lab identified two distinct populations of neurons in a different part of the amygdala, known as the basolateral amygdala (BLA). These two populations are genetically programmed to encode either fearful or happy memories.
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