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

Area of Science:

• Neuroscience
• Psychophysiology
• Social Cognition

Background:

• C-tactile afferents (CTs) are mechanosensitive nerve fibers responding to gentle touch, hypothesized to mediate the rewarding aspects of social affiliation.
• Individual differences in CT-targeted touch pleasantness exist, and variations in vagally mediated high-frequency heart rate variability (HF-HRV) are linked to visual social cognition.
• The relationship between autonomic nervous system function (HF-HRV) and sensitivity to affective touch (CT afferents) remains largely unexplored.

Purpose of the Study:

• To investigate the association between resting-state HF-HRV and individual sensitivity to socially relevant, CT-targeted touch.
• To determine if autonomic control differences can explain variations in hedonic responses to affective touch.

Main Methods:

• Recorded 5-minute electrocardiograms (ECG) in 58 healthy participants to measure resting-state HF-HRV.
• Participants rated the pleasantness of robotically delivered touch at five different velocities (0.3, 1, 3, 10, 30 cm/s), including CT-optimal and non-optimal ranges.
• Analyzed the relationship between HF-HRV and the quadratic fit of touch pleasantness ratings using simple regression.

Main Results:

• Group-level analysis revealed touch pleasantness followed a negative quadratic function, with CT-optimal velocities (1-10 cm/s) rated as more pleasant than slower or faster speeds.
• Simple regression demonstrated that participants' HF-HRV significantly predicted the quadratic curve fit of their touch pleasantness ratings.
• Higher HF-HRV was associated with a better quadratic fit, indicating greater sensitivity to the optimal range of touch velocities.

Conclusions:

• Resting-state HF-HRV is significantly associated with individual differences in sensitivity to pleasant, CT-targeted touch.
• Trait differences in autonomic nervous system regulation, as reflected by HF-HRV, may underlie individual variations in affective touch perception.
• Findings support the hypothesis that autonomic control influences the processing of social-tactile cues, potentially impacting social cognition and affiliative behaviors.