Visceromotor areas (VMAs)

Introduced in Seth & Friston (2016) as the anatomical apex of the interoceptive-inference hierarchy: AIC, ACC, subgenual cortex (SGC), and OFC. VMAs are proposed to embody a generative model of interoceptive responses, issuing descending predictions that, once “unpacked” at the lowest hierarchical level, function as homeostatic set-points for autonomic reflexes.

The structural argument

The paper’s distinctive move is anatomical rather than purely functional: VMAs are agranular or dysgranular — they lack a well-formed granular layer IV, the canonical cytoarchitectural target of feedforward, prediction-error-carrying afferents in laminar models of predictive coding (Barbas-style). Lacking that input layer, VMAs are structurally suited to be a source of descending predictions rather than a recipient of ascending error — giving Seth’s predictive reading of interoception a structural foothold beyond the circumstantial functional evidence marshalled in Seth (2013). See feedforward-vs-predictive-interoception.

Connectivity

VMAs receive ascending viscerosensory projections from posterior and mid-insula, and send descending connections to subcortical, brainstem, and spinal targets involved in visceromotor control — notably the periaqueductal grey (PAG) and the parabrachial nucleus (PBN). Visceromotor efferents also directly innervate viscerosensory areas, potentially providing efference copy/corollary discharge that helps construct the ascending interoceptive prediction errors those same predictions are meant to explain away.

Convergence with the constructionist “core affect” network

The VMA set (AIC, ACC, SGC/subgenual, OFC) overlaps substantially with the core affect network that Lindquist et al.’s (2012) neuroimaging meta-analysis identifies empirically (amygdala, insula, mOFC, lOFC, ACC, thalamus, hypothalamus, BNST, basal forebrain, PAG) as the domain-general substrate of emotional experience across categories. Two independent research programs — a predictive-coding anatomical argument (Seth & Friston) and a psychological-constructionist meta-analytic one (Lindquist et al.) — converge on nearly the same set of regions from different starting assumptions and different evidence (cytoarchitecture vs. cross-study activation consistency), though they do not cite one another.