Neurophysiological correlates of dysregulated emotional arousal in severe traumatic brain injury

OBJECTIVE: This study aimed to elucidate relationships between dysregulated emotional arousal after severe traumatic brain injury (TBI), alpha power and skin conductance levels (SCL), and brain atrophy.

METHODS: Nineteen adults with severe TBI and 19 age-, education-, and gender-matched controls (all p's>0.05) participated. Magnetic resonance imaging (MRI) scan established bilateral insulae and amygdale volumes. Mean EEG alpha power and SCLs were recorded simultaneously across four, 2 min conditions: eyes-closed pre-task baseline, view neutral face, happy face and angry face.

RESULTS: Scalp-wide alpha suppression occurred from pre-task baseline to the face-viewing conditions (p<.001), but was diminished in TBI (p=.04). TBI participants exhibited marginally significantly lower SCL (p=.051), and elevated alpha power hemispherically, contrasting with controls' midline dominance (p<.01). Significant atrophy was observed in most structures in TBI participants (p's=.004-0.04). Larger left insula, left amygdala and right amygdala correlated positively with alpha power and alpha suppression, and SCLs; all structures uniquely contributed to variance in arousal.

CONCLUSIONS: Findings suggest that alpha power provides a sensitive measure of dysregulated emotional arousal post-TBI. Atrophy in pertinent brain structures may contribute to these disturbances.

SIGNIFICANCE: These findings have potential implications for the assessment and remediation of TBI-related arousal deficits, by directing more targeted remediation, and better assessing post-TBI recovery.