“Human beings perform optimally at an intermediate level of alertness and arousal where they are attending to appropriate stimuli rather than being either anxious or somnolent,” said Mriganka Sur, Paul and Lilah E. Newton Professor in the Department of Brain and Cognitive Sciences. “But how does this come about?”
Postdoc Vincent Breton-Provencher brought this question to the lab and led the study published Jan.uary 14 in Nature Neuroscience. In a series of experiments in mice, he shows how connections from around the mammalian brain stimulate two key cell types in a region called the locus coeruleus (LC) to moderate arousal in two different ways. A region particularly involved in exerting one means of this calming influence, the prefrontal cortex, is a center of executive function, which suggests there may indeed be a circuit for the brain to attempt conscious control of arousal.
“We know, and a mouse knows, too, that to counter anxiety or excessive arousal one needs a higher level cognitive input,” said Sur, the study’s senior author.
By explaining more about how the brain keeps arousal in check, Sur said, the study therefore might also provide insight into the neural mechanisms contributing to anxiety or chronic stress, in which arousal appears insufficiently controlled. It might also provide greater mechanistic understanding of why cognitive behavioral therapy can help patients manage anxiety, Sur added.