Active interoceptive inference and the emotional brain (Seth & Friston 2016)
The formal successor to Seth (2013), co-authored with Karl Friston, published in a Royal Society theme issue on “Interoception beyond homeostasis.” It restates interoceptive-inference using the full free-energy/active-inference apparatus and adds two things the 2013 paper lacked: a structural (cytoarchitectural) argument for why the interoceptive hierarchy should be read as predictive rather than feed-forward, and worked clinical extensions (autism, depression/fatigue).
Epistemic vs instrumental active inference
A distinction largely absent from Seth (2013): epistemic active inference selects actions expected to increase the fit between predictive models and the hidden causes of sensation (saccades; exploratory movements that inform self-models) — a curiosity-driven, information-seeking mode. Instrumental active inference leverages an existing predictive model to achieve control of sensory variables, invoking Powers’s perceptual control theory: “control systems control what they sense, not what they do.” Interoceptive/autonomic regulation is instrumental active inference — descending predictions set homeostatic points that autonomic reflexes fulfill. Both are still active (action-based) routes to prediction-error reduction; the paper does not posit a passive/perceptual third mode alongside them, which is directly relevant to perceptual-inference-as-regulation — see that debate page for the tension this raises against Farb et al.’s active/perceptual dichotomy.
Visceromotor areas: an anatomical argument for prediction
Where Seth (2013) placed the AIC alone as comparator, this paper broadens and sharpens the neuroanatomy: visceromotor areas (VMAs) — AIC, ACC, subgenual cortex (SGC), and orbitofrontal cortex (OFC) — sit at the top of the interoceptive hierarchy. The key new argument is cytoarchitectural: these regions are agranular or dysgranular, lacking a well-formed granular layer IV (the canonical target of feedforward, prediction-error-carrying input in laminar predictive-coding models). Structure, not just function, marks them as a source of descending predictions rather than a recipient of ascending error. This gives Seth’s side of feedforward-vs-predictive-interoception a harder anatomical foothold than the functional/circumstantial evidence Seth (2013) relied on.
VMAs receive ascending viscerosensory input from posterior/mid-insula and send descending projections to PAG and the parabrachial nucleus (PBN) for visceromotor control; visceromotor efferents also directly innervate viscerosensory areas, potentially supplying efference copy/corollary discharge that helps construct ascending interoceptive prediction errors.
Homeostasis and allostasis as a precision problem
Refines allostasis: whether the system falls back on low-level homeostatic reflexes (e.g., hypoglycemia triggering glucose mobilization) or engages higher, goal-directed allostatic behaviour (preparing and eating a meal) is cast as a function of the confidence (precision) placed in deeper expectations about future action — not a qualitatively different system, but a different point on the same precision-weighted hierarchy.
Clinical extensions
- Autism: a failure to attenuate the precision of interoceptive prediction errors produces autonomic hypersensitivity and precludes learning that a nurturing (m)other is the same object across affiliative interactions (since the absence of expected interoceptive cues, e.g. during breastfeeding, cannot be discounted) — with knock-on effects for self/other differentiation, attachment, and central coherence. Introduces the interoceptive trait prediction error (ITPE), operationalized as the mismatch between objective heartbeat-detection accuracy and subjective interoceptive-sensibility questionnaires; elevated in autism and correlated with self-reported anxiety in both autistic and control samples (recalling Paulus & Stein’s non-Bayesian anxiety-as-interoceptive-prediction-error proposal). Flags a confound: autism’s frequent co-occurrence with alexithymia, and inconsistent findings across studies on the direction of interoceptive-sensibility change in autism.
- Depression and fatigue: two (not-yet-adjudicated) accounts. (1) Noisy/imprecise interoceptive afferents (endocrine, immunological) reduce precision-weighting of ascending interoceptive signals, increasing reliance on now-dysfunctional interoceptive priors — a positive-feedback spiral into dyshomeostasis, fatigue, and sickness behaviour. (2) Fatigue and depression as metacognitive beliefs about low allostatic self-efficacy following prolonged experienced dyshomeostasis, paralleling learned-helplessness accounts. Both are linked to agranular visceromotor cortex pathophysiology in depression.
Relation to Seth (2013)
Largely the same core claim (emotion as interoceptive predictive coding; AIC/VMAs as comparator; active inference as autonomic enslavement), restated with Friston as co-author and with three substantive additions: the agranular-cortex structural argument, the epistemic/instrumental active-inference distinction, and the autism/depression clinical program. Read together with Craig (2009) and Lindquist et al. (2012), the AIC/ACC/OFC complex this paper calls “VMAs” is very close to the “core affect” network Lindquist’s meta-analysis identifies empirically — a convergence between a predictive-coding neuroanatomical argument and a psychological-constructionist meta-analytic one, made independently and from different starting assumptions. See visceromotor-areas.