RELATED STORY: Rita Allen Foundation Scholar Michael Long Reveals How Brain Circuits Help Birds Learn to Sing
Michael Long received a B.S. in biology and a B.A. in psychology from Rhodes College, and earned a Ph.D. in neuroscience from Brown University, where he worked with Barry Connors. He conducted postdoctoral research in the laboratory of Michale Fee at the Massachusetts Institute of Technology, and joined the faculty of the New York University School of Medicine in 2010. In addition to being a Rita Allen Foundation Scholar, Long has received an Esther A. and Joseph Klingenstein Fellowship Award in the Neurosciences and a Robertson Neuroscience Investigator award from the New York Stem Cell Foundation.
Sequential activity appears to be a broad feature in neural circuits and is thought to play an important role in orchestrating complex behaviors. These sequences can be generated in a number of ways, although we know very little about their underlying connectivity, making it difficult to predict a precise mechanism. Long and his colleagues have taken an anatomical approach to understand connectivity in the zebra finch HVC, a premotor circuit that drives a complex learned vocal sequence. Previous work suggested that the neural sequence in HVC emerges from a chain of synaptically connected projection neurons, but anatomical evidence for such direct synaptic connections is lacking. Long’s group identified a large number of premotor-premotor contacts and characterized their distribution along the dendrites and axon collaterals. Surprisingly, they found that proximal and distal connectivity is highly cell-type specific. Locally, premotor neuron axons primarily target interneurons, while distally they form most of their synapses with excitatory neurons, many of which are onto other premotor neurons. Their results show that monosynaptically connected premotor neurons are spatially decorrelated and suggest that the chain is propagated through linked winner-take-all modules.