Strategy‐based reasoning training modulates cortical thickness and resting‐state functional connectivity in adults with chronic traumatic brain injury

Prior studies have demonstrated training‐induced changes in the healthy adult brain. Yet, it remains unclear how the injured brain responds to cognitive training months‐to‐years after injury. Methods Sixty individuals with chronic traumatic brain injury ( TBI ) were randomized into either strategy‐based ( N  = 31) or knowledge‐based ( N  = 29) training for 8 weeks. We measured cortical thickness and resting‐state functional connectivity (rs FC ) before training, immediately posttraining, and 3 months posttraining. Results Relative to the knowledge‐based training group, the cortical thickness of the strategy‐based training group showed diverse temporal patterns of changes over multiple brain regions ( p vertex  < .05, p cluster  < .05): (1) increases followed by decreases, (2) monotonic increases, and (3) monotonic decreases. However, network‐based statistics ( NBS ) analysis of rs FC among these regions revealed that the strategy‐based training group induced only monotonic increases in connectivity, relative to the knowledge‐based training group (| Z | > 1.96, p NBS  < 0.05). Complementing the rs FC results, the strategy‐based training group yielded monotonic improvement in scores for the trail‐making test ( p  <   .05). Analyses of brain–behavior relationships revealed that improvement in trail‐making scores were associated with training‐induced changes in cortical thickness ( p vertex  < .05, p cluster  < .05) and rs FC ( p vertex  < .05, p cluster  < .005) within the strategy‐based training group. Conclusions These findings suggest that training‐induced brain plasticity continues through chronic phases of TBI and that brain connectivity and cortical thickness may serve as markers of plasticity.