Long-Term Effects of Concussion on Electrophysiological Indices of Attention in Varsity College Athletes: An Event-Related Potential and Standardized Low-Resolution Brain Electromagnetic Tomography Approach

Abstract

This study investigated the effects of a past concussion on electrophysiological indices of attention in college athletes. Forty-four varsity football athletes (22 with at least one past concussion) participated in three neuropsychological tests and a two-tone auditory oddball task while undergoing high-density event-related potential (ERP) recording. Athletes previously diagnosed with a concussion experienced their most recent injury approximately 4 years before testing. Previously concussed and control athletes performed equivalently on three neuropsychological tests. Behavioral accuracy and reaction times on the oddball task were also equivalent across groups. However, athletes with a concussion history exhibited significantly larger N2 and P3b amplitudes and longer P3b latencies. Source localization using standardized low-resolution brain electromagnetic tomography indicated that athletes with a history of concussion generated larger electrical current density in the left inferior parietal gyrus compared to control athletes. These findings support the hypothesis that individuals with a past concussion recruit compensatory neural resources in order to meet executive functioning demands. High-density ERP measures combined with source localization provide an important method to detect long-term neural consequences of concussion in the absence of impaired neuropsychological performance.

Keywords: adult brain injury; cognitive function; electrophysiology; neuropsychology; traumatic brain injury.

FIG 1.

Averaged ERP waveforms are represented by group (concussion history = gray; control = black) and condition (target = solid; nontarget = dashed). (A) P3b-positive amplitudes and latencies extracted from a regional average of parietal electrodes between 260 and 388 ms post-stimulus onset. (B) N2-negative amplitudes and latencies extracted from a regional average of pre-frontal electrodes between 150 and 300 ms post-stimulus onset. *p < 0.05. ERP, event-related potential.

FIG 2.

Sagittal, coronal, and axial sections showing electrical current density maps (in nanoamp meters; nA) of the P3b component (target) for the (A) concussion history and (B) control groups. Current density patterns fit to the Montreal Neurological Institute's typical MRI head model. Cross-hairs intersect the left inferior parietal gyrus (xyz = −31, −46, 43; Brodmann area, 40) and indicate significant group differences (p < 0.001). Following radiological convention, the left hemispheres are presented on the right sides of each MRI model and the right hemispheres are presented on the left sides. L, left; MRI, magnetic resonance imaging; R, right.