Impulsivity and concussion in juvenile rats: examining molecular and structural aspects of the frontostriatal pathway
Date
2015
Authors
Hehar, Harleen
Yeates, Keith
Kolb, Bryan
Esser, Michael J.
Mychasiuk, Richelle
Journal Title
Journal ISSN
Volume Title
Publisher
Public Library of Science
Abstract
Impulsivity and poor executive control have been implicated in the pathogenesis of many
developmental and neuropsychiatric disorders. Similarly, concussions/mild traumatic brain
injuries (mTBI) have been associated with increased risk for neuropsychiatric disorders and
the development of impulsivity and inattention. Researchers and epidemiologists have
therefore considered whether or not concussions induce symptoms of attention-deficit/
hyperactivity disorder (ADHD), or merely unmask impulsive tendencies that were already
present. The purpose of this study was to determine if a single concussion in adolescence
could induce ADHD-like impulsivity and impaired response inhibition, and subsequently
determine if inherent impulsivity prior to a pediatric mTBI would exacerbate post-concussion
symptomology with a specific emphasis on impulsive and inattentive behaviours. As these
behaviours are believed to be associated with the frontostriatal circuit involving the nucleus
accumbens (NAc) and the prefrontal cortex (PFC), the expression patterns of 8 genes
(Comt, Drd2, Drd3, Drd4, Maoa, Sert, Tph1, and Tph2) from these two regions were examined.
In addition, Golgi-Cox staining of medium spiny neurons in the NAc provided a neuroanatomical
examination of mTBI-induced structural changes. The study found that a single
early brain injury could induce impulsivity and impairments in response inhibition that were
more pronounced in males. Interestingly, when animals with inherent impulsivity experienced
mTBI, injury-related deficits were exacerbated in female animals. The single concussion
increased dendritic branching, but reduced synaptic density in the NAc, and these
changes were likely associated with the increase in impulsivity. Finally, mTBI-induced
impulsivity was associated with modifications to gene expression that differed dramatically
from the gene expression pattern associated with inherent impulsivity, despite very similar
behavioural phenotypes. Our findings suggest the need to tailor treatment strategies for
mTBI in light of an individual’s premorbid characteristics, given significant differences in
molecular profiles of the frontostriatal circuits that depend upon sex and the etiology of the
behavioural phenotype
Description
Sherpa Romeo green journal: open access
Keywords
Impulsivity , Impulsive , Inattention , ADHD , Concussion , Brain injury , Mild traumatic brain injuries , mTBI , Frontostriatal , Brain--Concussion
Citation
Hehar, H., Yeates, K., Kolb, B., Esser, M. J., & Mychasiuk, R. (2015). Impulsivity and concussion in juvenile rats: examining molecular and structural aspects of the frontostriatal pathway. PLoS ONE, 19(10), e0139842. doi:10.1371/journal.pone.0139842