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Updated: Apr 21, 2026

Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury
Published on: November 19, 2012
Damage to histaminergic tuberomammillary neurons and other hypothalamic neurons with traumatic brain injury
Philipp O Valko1, Yury V Gavrilov, Mihoko Yamamoto
1Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA; Department of Neurology, University Hospital Zurich, Zurich, Switzerland.
Abstract:
The need for increased sleep after traumatic brain injury is a common and disabling complaint, yet its etiology is unknown. Previous studies have demonstrated diffuse damage to various hypothalamic systems, but the integrity of the histaminergic tuberomammillary nucleus, a major arousal-promoting system located in the posterior hypothalamus, has never been examined in head trauma patients. Here, we demonstrate that severe head trauma is associated with a marked loss (41%) of histaminergic neurons. Reduced histamine signaling may contribute to increased sleep need, and therapies that enhance histaminergic tone may improve arousal after head trauma or other conditions.
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