Hemispheric divergence of interoceptive processing across psychiatric disorders

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• Conscious perception of bodily states involves interactions between attention and visceral inputs.
• Aberrant interoceptive symptoms are common in psychiatric disorders, but the underlying neural mechanisms are unclear.

Purpose of the Study:

• To investigate the neural substrates of the interface between top-down attention and bottom-up visceral processing.
• To examine differences in insular cortex activity and connectivity between individuals with anxiety, depression, and/or eating disorders (ADE) and healthy comparisons (HC).

Main Methods:

• A preregistered functional neuroimaging study involving 46 individuals with ADE and 46 propensity-matched HC.
• Two interoceptive tasks were used: an attention task (directing attention to cardiorespiratory or visual signals) and a perturbation task (using isoproterenol infusions to induce visceral sensations).
• Neural activity and functional connectivity within the insular cortex were analyzed.

Main Results:

• Neural activation converged on the bilateral insular cortex, specifically the granular and ventral dysgranular subregions, across both tasks.
• The ADE group showed asymmetric insular activation patterns compared to HCs, with altered overlap in the left dysgranular insula.
• The ADE group exhibited reduced agranular anterior insula activation during periods of bodily uncertainty.
• Post-task changes in insula functional connectivity correlated with anxiety and depression severity.

Conclusions:

• The dysgranular mid-insula serves as a critical cortical interface integrating attention, prediction, and real-time bodily inputs.
• This region is implicated as a potential 'locus of disruption' in psychiatric disorders characterized by interoceptive disturbances.
• Findings highlight the role of insular cortex dysfunction in the symptomatology of anxiety, depression, and eating disorders.