Neural Correlates of Processing Speed During a Cognitive Task in Moderate to Severe Traumatic Brain Injury

Objective: Processing speed, commonly measured by reaction time, during cognitive tasks is often impaired in individuals with traumatic brain injuries (TBI). This study used functional magnetic resonance imaging (fMRI) during a visual cognitive task to identify patterns of activation correlated with reaction time in individuals with TBI compared to healthy controls (HCs). Methods: Adults with moderate to severe TBI and matched healthy controls completed a computerized visual cognitive task involving memory of polygons during an fMRI scan. Reaction time and accuracy were measured during the choice selection. Structural and functional imaging was gathered to analyze differences in the activation correlated with reaction time between the TBI and HC groups. Results: It was found that there were no significant differences in reaction time, but the HC group had higher accuracy on the task. There were no areas of activation correlated with reaction time that were greater for TBI than in HCs, conversely, there were two clusters of activation correlated with reaction time in the occipital lobe that were greater for the HCs than the TBI group. Conclusions: These findings suggest there may be a speed-accuracy tradeoff during cognitive tasks for individuals with TBI. The activation results suggest that the HCs may be able to recruit more areas to complete the task faster than the TBI group. These results may have implications for treatment options after a TBI occurs.