Alana Fisher

Neurophysiological correlates of dysregulated emotional arousal in severe traumatic brain injury.

OBJECTIVEnThis 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.nnnMETHODSnNineteen adults with severe TBI and 19 age-, education-, and gender-matched controls (all ps>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.nnnRESULTSnScalp-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 (ps=.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.nnnCONCLUSIONSnFindings suggest that alpha power provides a sensitive measure of dysregulated emotional arousal post-TBI. Atrophy in pertinent brain structures may contribute to these disturbances.nnnSIGNIFICANCEnThese 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.

Reduced heart rate variability in chronic severe traumatic brain injury: Association with impaired emotional and social functioning, and potential for treatment using biofeedback

Heart rate variability (HRV) may provide an index of capacity for social functioning and may be remediated by HRV biofeedback. Given reductions in HRV are found following traumatic brain injury (TBI), the present study aimed to determine whether lower HRV in TBI is associated with social function, and whether HRV biofeedback might be a useful remediation technique in this population. Resting state HRV and measures of social and emotional processing were collected in 30 individuals with severe TBI (3–34u2005years post-injury) and 30 controls. This was followed by a single session of HRV biofeedback. HRV was positively associated with social cognition and empathy, and negatively associated with alexithymia for the TBI group. Both TBI and control groups showed significantly increased HRV on both time-domain (i.e., SDNN, rMSSD) and frequency-domain measures (LF, HF, LF:HF ratio) during biofeedback compared to baseline. These results suggest that decreased HRV is linked to social and emotional function following severe TBI, and may be a novel target for therapy using HRV biofeedback techniques.

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.

Brain volume loss contributes to arousal and empathy dysregulation following severe traumatic brain injury

Severe traumatic brain injury (TBI) often leads to deficits in physiological arousal and empathy, which are thought to be linked. This study examined whether injury-related brain volume loss in key limbic system structures is associated with these deficits. Twenty-four adults with TBI and 24 matched Controls underwent MRI scans to establish grey matter volumes in the amygdala, thalamus, and hippocampus. EEG and skin conductance levels were recorded to index basal physiological arousal. Self-report emotional empathy levels were also assessed. The TBI group had reduced brain volumes, topographic alpha differences, and lower emotional empathy compared to Controls. Regional brain volumes were differentially correlated to arousal and self-report empathy. Importantly, lower volume in pertinent brain structures correlated with lower empathy, for participants with and without TBI. Overall we provide new insights into empathic processes after TBI and their relationship to brain volume loss.

Impaired perception of sincerity after severe traumatic brain injury

BACKGROUNDnPeople with a severe traumatic brain injury (TBI) often experience problems understanding non-literal utterances such as sarcasm and lies in dyadic exchanges. This study aimed to investigate whether these problems extend to settings where speakers vary in their degree of sincerity and whether such problems are associated with deficits in social cognitive abilities (emotion perception, theory of mind, and self-reported empathy) or cognitive abilities (abstract reasoning, working memory, processing speed, attentional switching).nnnMETHODSnThirty-one adults with severe TBI (24 males) and 25 demographically matched controls (20 males) participated. They watched video vignettes depicting four actors volunteering for additional duties. Each speaker made a limited verbal response which literally suggested a willingness to be involved, but the sincerity with which the response was made was tempered by the actors emotional demeanour. Participants rated each speaker in the vignettes for degree of sincerity (0-100%). Standardized measures of cognitive and social cognitive function were also taken.nnnRESULTSnControl participants had excellent agreement (αxa0=xa0.90) in their rankings of actors according to sincerity. TBI participants were less consistent (αxa0=xa0.65). Overall, they were sensitive to decreasing sincerity but generally less accurate than control participants. They were poorer at differentiating between levels of sincerity and rated insincere expressions as more sincere, although they rated sincere expressions similarly. Poorer working memory and poorer social cognition were associated with poorer sincerity/sarcasm detection in the participants with TBI, but only social cognition was uniquely associated.nnnCONCLUSIONSnSome adults with TBI have difficulty assessing the level of sincerity of speakers. Moreover, poorer social cognition abilities are associated with this difficulty.

When diplomacy fails: difficulty understanding hints following severe traumatic brain injury

Background: In the absence of aphasia, many people with severe traumatic brain injuries (TBI) have difficulty with communication. In particular, they have difficulty understanding conversational inference. Poor social cognition is also prevalent following TBI. Aims: This study aimed to examine the role of social cognition in the ability to recognise conversational inference in the form of hints. Methods and procedures: 31 adults (22 men: mean age 45 years) with chronic (mean time since injury = 15.12 years) and severe TBI (mean post traumatic amnesia (PTA) of 32.74 days) and 24 adults (14 men: mean age 46.1 years) from the community participated. They were compared for their comprehension of two kinds of video vignettes in which professional actors made progressively more explicit hints. In one version, the conversational tone was neutral, in the other emotional. They were also assessed on an independent measure of social cognition (TASIT). Outcomes & results: The adults with TBI recognised neutral hints at a normal rate but, unlike the community controls, were not facilitated by overtly emotional hints. Social cognition performance was related to performance on both types of hint. Improved performance on the emotional hints was not uniquely predicted by social cognition but, rather, by processing speed and possibly also stress in the group with TBI. Conclusions: People with TBI appear to have difficulty using emotional cues to infer speaker meaning. This may reflect cognitive slowing and also anxiety and stress. This has implications for both remediation of such deficits and for educating others who interact with people with TBI.