Microstructural Brain Correlates of Inter-individual Differences in Respiratory Interoception

Interoception, the perception and integration of physiological signals, is a fundamental aspect of self-awareness and homeostasis. While previous work has explored interoceptive processing in relation to the cardiac system, research in the respiratory domain, particularly in relation to brain structure and function, is limited. To address this gap, we utilised a Bayesian psychophysical model to quantify perceptual, metacognitive, and affective dimensions of respiratory interoception in a sample of 207 healthy participants. We also measured individual whole-brain microstructural indices of myelination, myeloarchitecture, and cortical iron using quantitative brain imaging. Voxel-based quantification analyses revealed distinct patterns of cortical microstructure in the insular, cingulate, and primary sensory cortices, which underpin interoceptive perceptual sensitivity and precision. In addition, metacognitive bias was associated with increased myelination of the cingulate cortex and periaqueductal grey, while metacognitive sensitivity correlated with myelination of the midline prefrontal cortex. At an affective level, sensitivity to respiratory resistance was related to the myelination of the primary somatosensory cortex. By revealing specific histological brain patterns tied to individual differences in respiratory interoception, our results uncover the neural pathways that govern perceptual, metacognitive, and emotional facets of interoceptive processing.