I'd like to know what happens to a human being with a lesion that completely destroys the locus coeruleus. Thank you.

-- Citlalli Molina (dawnsteag@hotmail.com), March 10, 2004

Answers

Just put the words "locus coeruleus lesion" in Google and you'll find lots of information online.

-- Hendrika Vande Kemp (hendrika@earthlink.net), March 10, 2004.

Locus coeruleus (hereafter, lc) is a relatively small nucleus that is found on both sides of the upper pons about 1/3 of the distance between the medulla oblongata and the midbrain. Unless it was a target in human clinical-based brain research (and I know of no present justification for that) it is highly unlikely that lc on both sides of the brain would be damaged such that the damage was limited to the lc. Therefore, one is unlikely to encounter a human case of pure and total lc damage; that is, damage is likely to be incomplete or confounded with damage to other brain areas.

Neurons of lc are mostly associated with the neurotransmitter, norepinephrine, and unusual for the brain, lc neurons project widely and diffusly. For example, a single lc neuron might send axonal branches over most of the cerebellar or cerebral cortexes. Loosely speaking, norepinephrine appears, generally, to have facilitatory effects on the activation of other neurons. Thus, given the diffuse projections of lc neurons, lc is often associated functionally with general activation or arousal, for example, of the cerebral cortex.

Armed with that information, one might be tempted to suggest that the absence of lc neurons (e.g., if a total, unconfounded lesion did occur) might result in a generally more inhibited organism as manifested in numerous physiological or behavioral effects. However, the nervous system is also characterized by redundancies in mechansism and function, so one might also imagine relatively little effect of a total lc lesion in a human.

-- Roger K. Thomas (rkthomas@uga.edu), March 15, 2004.