ABSTRACT
Background Understanding behavioral and neural underpinnings of post-concussion recovery of working memory function is critically important for improving clinical outcomes and adequately planning return-to-activity decisions. Previous studies provided inconsistent results due to small sample sizes and the use of a mixed population of participants who were at different post-injury time points.
Methods To better understand behavioral and neural correlates of working memory recover during the first 6 months post-concussion, we used functional magnetic resonance imaging (fMRI) to scan 45 concussed adolescents [CONC] at baseline (<10 days post-concussion) and again at 6 months post-concussion. Healthy control [HC] adolescents without a history of concussion were scanned once. During the scans, participants performed 1-back (easy) and 2-back (difficult) working memory tasks with the letters as the stimuli and angry, happy, neutral, and sad faces as distractors.
Results By the 6-month follow-up, all affected adolescents were asymptomatic and cleared to return-to-activity. Working memory function recovery was reflected by faster and more accurate performance at 6 months vs. baseline (p-values<0.05). It was also characterized by significant difficulty-related activation increases in the left inferior frontal gyrus (LIFG) and the left orbitofrontal cortex (LOFC) at 6 months vs. baseline.
Conclusion Post-concussion recovery is associated with significant performance improvements in speed and accuracy, as well as normalization of brain responses in the LIFG and LOFC during the n-back task. The observed patterns of LOFC activation might reflect compensatory strategies to distribute neural processing and reduce neural fatigue post-concussion.
Competing Interest Statement
Drs. Manelis, Lima Santos, Hickey, and Versace, Mr. Suss, and Ms. Perry have no conflict of interest to declare. Drs. Kontos and Collins receive book royalties from APA Books, and funding for their research through the University of Pittsburgh from the Centers for Disease Control and Prevention, Chuck Noll Foundation for Brain Injury Research, Department of Defense (CDMRP, USAMRAA, USUHS), National Football League, National Institutes of Health (NICHD, NIMH, NINDS), and private donors.
Funding Statement
This work was supported by grants from the National Institute of Health (R01MH11488101; MPI Versace and Kontos), and Chuck Noll Foundation for Brain Injury Research (FP00004146; PI Versace).
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The study was approved by the University of Pittsburgh Institutional Review Board (IRB number STUDY19030360). Written informed assent was obtained from all participants, and written informed consent was obtained from all caregivers.
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All data produced in the present study are available upon reasonable request to the authors