Philosophers have long struggled to define human consciousness. Now, a team of researchers led by neurologists at Beth Israel Deaconess Medical Center (BIDMC) in Boston has pinpointed the regions of the brain that may play a role in maintaining it. Their findings, which have already garnered multiple awards from the American Academy of Neurology, were published online on November 4, 2016 in that society's journal, Neurology. The article is titled “A Human Brain Network Derived from Coma-Causing Brainstem Lesions.” “For the first time, we have found a connection between the brainstem region involved in arousal and regions involved in awareness, two prerequisites for consciousness," said Michael D. Fox, M.D., Ph.D., Director of the Laboratory for Brain Network Imaging and Modulation and the Associate Director of the Berenson-Allen Center for Noninvasive Brain Stimulation at BIDMC. "A lot of pieces of evidence all came together to point to this network playing a role in human consciousness." Classical neurology holds that arousal and awareness are two critical components of consciousness. Arousal is likely regulated by the brainstem - the portion of the brain, contiguous with the spinal cord, that is responsible for the sleep/wake cycle and cardiac and respiratory rates. Awareness, another critical component of consciousness, has long been thought to reside somewhere in the cortex, the outer layer of the brain responsible for many of its higher functions. In the current study, the researchers analyzed 36 patients with brainstem lesions, of which 12 led to coma and 24 did not. Mapping the injuries revealed that a small "coma-specific" area of the brainstem - the rostral dorsolateral pontine tegmentum - was significantly associated with coma.
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