Tolerance of locus coeruleus neurones to morphine and suppression of withdrawal response by clonidine. (semanticscholar.org)
But, in the sleep - deprived brain, the amygdala seemed to be «rewired,» coupling instead with a brain stem area called the locus coeruleus, which secretes norepinephrine, a precursor of the hormone adrenaline that triggers fight - or - flight type reactions. (scientificamerican.com)