The Heart in the Mind: A Systematic Review and Meta-Analysis of the Association Between Theory of Mind and Cardiac Vagal Tone

High frequency heart rate variability is associated with sensitivity to affective touch

C-tactile afferents (CTs) are a class of unmyelinated, mechanosensitive nerve fibre that respond optimally to skin temperature, slow moving touch typical of a caress. They are hypothesised to signal the rewarding value of affiliative tactile interactions. While CT firing frequency is positively correlated with subjective ratings of touch pleasantness, trait differences in sensitivity to the specific hedonic value of CT targeted touch have been reported. Inter-individual differences in vagally mediated, high frequency heart rate variability (HF-HRV) have been linked to variation in visual social cognition. Thus, the aim of the present study was to examine the relationship between resting state HF-HRV and sensitivity to socially relevant CT targeted touch. 58 healthy participants first had a 5-minute electrocardiogram. They then rated the pleasantness of 5 randomly presented velocities of robotically delivered touch. Three velocities fell within (1, 3, 10 cm/s) and two outside (0.3, 30 cm/s) the CT optimal range. Each velocity was delivered twice. On a group level, affective touch ratings were described by a negative quadratic function, with CT optimal velocities rated as more pleasant than slower and faster speeds. Simple regression analysis confirmed participants' HF-HRV was significantly predicted by the quadratic curve fit of their touch ratings, with higher HF-HRV associated with a better quadratic fit. These findings indicate that, in line with previous observations that higher HF-HRV is associated with enhanced sensitivity to visual social cues, trait differences in autonomic control could account for previously reported individual differences in CT sensitivity.

From One's Heart to the Mind of Others: A Study in School-Aged Children

Studies have shown a significant association between effective parasympathetic modulation of the heart and processes linked to social cognition. Particularly, Quintana and colleagues documented a relation between vagally-mediated heart rate variability (vmHRV) and performance on a theory of mind (ToM) task, namely, the Reading the Mind in the Eyes Test (RMET), in a sample of university students. The purpose of the present study was to test whether such result would extend to a sample of school-aged children (7-9 years old) using the child version of the RMET. In addition, the Eyes Test Revised was administered as it is more suitable to evaluate ToM during childhood. Results supported the positive association between vmHRV and ToM abilities, replicating and extending previous results obtained in young adults. The current study adds to the existing literature pointing to HRV as a putative biomarker of social cognition abilities.

Unveiling the role of cerebellar alterations in the autonomic nervous system: a systematic review of autonomic dysfunction in spinocerebellar ataxias

BACKGROUND

Autonomic dysfunctions are prevalent in several cerebellar disorders, but they have not been systematically investigated in spinocerebellar ataxias (SCAs). Studies investigating autonomic deficits in SCAs are fragmented, with each one focusing on different autonomic dysfunctions and different SCA subtypes.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, we conducted a systematic review of the literature to assess the presence of autonomic dysfunctions in various SCAs. PubMed served as the primary database, and the Rayyan web application was employed for study screening.

RESULTS

We identified 46 articles investigating at least one autonomic function in patients with SCA. The results were analyzed and categorized based on the genetic subtype of SCA, thereby characterizing the specific autonomic deficits associated with each subtype.

CONCLUSION

This review confirms the presence of autonomic dysfunctions in various genetic subtypes of SCA, underscoring the cerebellum's role in the autonomic nervous system (ANS). It also emphasizes the importance of investigating these functions in clinical practice.

Modulatory effects of transcranial direct current stimulation of right insula on compassion motivation

Background

Compassion motivation is associated with increased heart rate variability (HRV), reflecting a calm and self-soothing physiological state. Recent work, however, suggests that this association is dynamic for the specific components of compassion.

Objectives

The present study adopted anodal transcranial direct current stimulation (tDCS) targeting the right insula to see whether this would modulate the sensitivity to suffering and the commitment to engage in helpful actions (i.e., the components of compassion motivation).

Method

Ninety-seven healthy individuals underwent 15-min anodal or sham tDCS over the frontotemporal lobe, while watching a video inducing empathic sensitivity and performing a Redistribution Game. Tonic and phasic HRV, dispositional traits, and momentary affects were assessed.

Results

Compared to sham condition, anodal stimulation favored significant i) HRV reductions during the video and HRV increases during the Redistribution Game; ii) decreases in self-reported levels of negative affect and increases in positive affect during task when the latter was preceded by the video, without influencing altruistic behavior.

Conclusions

Anodal tDCS over the right insula may modulate the engagement phase of compassion by intensifying the psychophysiological sensitivity to signals of distress and protecting from being subjectively overwhelmed by it.

Using Digital Biomarkers for Objective Assessment of Perfusionists' Workload and Acute Stress During Cardiac Surgery

The cardiac operating room (OR) is a high-risk, high-stakes environment inserted into a complex socio-technical healthcare system. During cardiopulmonary bypass (CPB), the most critical phase of cardiac surgery, the perfusionist has a crucial role within the interprofessional OR team, being responsible for optimizing patient perfusion while coordinating other tasks with the surgeon, anesthesiologist, and nurses. The aim of this study was to investigate objective digital biomarkers of perfusionists' workload and stress derived from heart rate variability (HRV) metrics captured via a wearable physiological sensor in a real cardiac OR. We explored the relationships between several HRV parameters and validated self-report measures of surgical task workload (SURG-TLX) and acute stress (STAI-SF), as well as surgical processes and outcome measures. We found that the frequency-domain HRV parameter HF relative power - FFT (%) presented the strongest association with task workload (correlation coefficient: -0.491, p-value: 0.003). We also found that the time-domain HRV parameter RMSSD (ms) presented the strongest correlation with perfusionists' acute stress (correlation coefficient: -0.489, p-value: 0.005). A few workload and stress biomarkers were also associated with bypass time and patient length of stay in the hospital. The findings from this study will inform future research regarding which HRV-based biomarkers are best suited for the development of cognitive support systems capable of monitoring surgical workload and stress in real time.

Evaluating the mechanisms of social cognition intervention in schizophrenia: A proof-of-concept trial

BACKGROUND

Social cognition interventions have shown promise for improving social functioning in people with schizophrenia. However, it is unclear how changes in social cognition affect social functioning. This study evaluates the impact of a social cognition intervention (GRASP - GRoup trAining for Social skills in Psychosis) on social cognition and social functioning outcomes and explores how two mechanisms, affect and physiological arousal, may drive changes.

METHOD

A two-arm single blind (assessor) randomized pilot trial comparing GRASP plus treatment-as-usual (TAU) with TAU alone in people with a diagnosis of schizophrenia. Participants were assessed with measures of social cognition, social functioning, and symptoms. All participants undertook a week-long mobile health assessment (experience sampling method) measuring social behavior and affect and used a wearable device recording autonomic activity. Assessments were performed at baseline and at week 10.

RESULTS

Forty-eight participants were randomly allocated to the treatment or control condition. Individuals randomized to GRASP did not show improvements on experience sampled social behavior and social cognition measures compared to controls. However, participants in the GRASP group enjoyed social contact more and had lower levels of negative affect and higher levels of positive affect compared to controls. There was no evidence of autonomic changes (i.e., electrodermal activity) associated with social behavior resulting from the therapy.

CONCLUSION

Social cognition interventions may be helpful in improving the quality of social contacts in people with schizophrenia by decreasing negative affect. Increase in social behavior may require longer periods to be evident. Future studies should consider how social cognition interventions may alter qualitative aspects associated with social behavior.