Fig. 3.

Schematic representation of dysfunction after traumatic brain injury (TBI). Monoamine disruptions are common starting mere hours after injury, with some continuing for months or longer. Monoamines influence various types of executive function, and this dysregulation after TBI may account for some of the common behavioral disturbances that are observed. Finally, both altered monoamines and functional impairments may converge to explain several post-TBI complications, including numerous therapeutic failures, and increased propensity for substance abuse and dependence. Notably, the intertwined nature of altered functional and structural changes make it difficult to fully parse the separate factors that challenge clinical treatment of TBI. DA, dopamine; 5-HT, 5-hydroxytryptamine; NE, norepinephrine.