Poster 7: Use of Functional Near Infrared Spectroscopy to Assess Changes in Prefrontal Activation Associated With Recovery of Response Inhibition Following Traumatic Brain Injury

Objective: To determine the relationship of prefrontal cerebral activation to inhibitory control following traumatic brain injury and to assess the relationship of improvements in inhibitory control to increased prefrontal activation as a function of recovery. Design: Mixed design with repeated measures taken weekly. Setting: Functional near infrared spectroscopy (fNIRS) lab in a postacute brain injury rehabilitation clinic. Participants: Patients (n=16) with subacute severe traumatic brain injury (TBI) and age-matched controls (n=16). Interventions: All subjects performed a modified computerized Stroop task while measures of cerebral activation were obtained via a 3 × 11 optode configuration covering anterior temporal and frontal cerebral regions. Main Outcome Measures: Errors during performance of the Stroop task and measures of cerebral activation assessed by relative oxyhemoglobin concentrations obtained in one tenth second intervals. Results: Controls demonstrated significantly fewer Stroop errors (P<.01) and greater prefrontal activation (P<.01) compared with patients during the first week. By the third week, there were no significant differences between groups for either the number of Stroop errors or for prefrontal cerebral activation. Further analyses revealed that patients demonstrated significantly fewer Stroop errors (P<.01) and greater prefrontal activation (P<.01) by the third week. Conclusions: Improved inhibitory control was observed over a 3-week period for patients with severe TBI. This improved control appeared to be related to increased prefrontal activation. Although recovery is thought to have been the major reason for this improvement, practice effects due to repeated trials cannot be ruled out. This latter point is of note, since use of fNIRS may provide a useful procedure for assessing brain activation related change as a function of rehabilitation. Future research should assess changes in cerebral activation with fNIRS as related to specific rehabilitation approaches.