Impaired emotional contagion following severe traumatic brain injury

Empathy deficits are widely-documented in individuals after severe traumatic brain injury (TBI). This study examined the relationship between empathy deficits and psychophysiological responsivity in adults with TBI to determine if impaired responsivity is ameliorated through repeated emotional stimulus presentations. Nineteen TBI participants (13 males; 41 years) and 25 control participants (14 males; 31 years) viewed five repetitions of six 2-min film clip segments containing pleasant, unpleasant, and neutral content. Facial muscle responses (zygomaticus and corrugator), tonic heart rate (HR) and skin conductance level (SCL) were recorded. Mean responses for each viewing period were compared to a pre-experiment 2-min resting baseline period. Self-reported emotional empathy was also assessed. TBI participants demonstrated identical EMG response patterns to controls, i.e. an initial large facial response to both pleasant and unpleasant films, followed by habituation over repetitions for pleasant films, and sustained response to unpleasant films. Additionally, an increase in both arousal and HR deceleration to stimulus repetitions was found, which was larger for TBI participants. Compared to controls, TBI participants self-reported lower emotional empathy, and had lower resting arousal, and these measures were positively correlated. Results are consistent with TBI producing impairments in emotional empathy and responsivity. While some normalisation of physiological arousal appeared with repeated stimulus presentations, this came at the cost of greater attentional effort.