The electrophysiological effects of a brain injury on auditory memory functioning: The QEEG correlates of impaired memory

The effect of a brain injury on the quantitative EEG (QEEG) variables during an auditory memory activation condition was examined with 56 normal subjects and 85 mild traumatic brain-injured (MTBI) subjects. An analysis was conducted on the different response patterns of the two groups, the variables which were correlated with memory performance in the brain-injured group, and the variables which predicted the memory score for the combined two groups (normal and brain injured). The three conditions included the input task, the immediate recall, and the delayed recall task. The consistent effect of a brain injury was a lowering of the connectivity patterns in the beta1 and beta2 frequencies (phase and coherences) and increases predominantly in the relative power of beta1 (13–32 Hz), which were correlated with the differences in recall. There is a subtle shift to right hemisphere/right temporal functioning and employment of the higher beta1 and beta2 frequencies (phase and coherence) in the response pattern of the MTBI subject. Memory functioning is predominantly positively correlated with connection activity (phase and coherence) and negatively correlated with beta activation at specific locations.