Anterior cingulate cortex (ACC)

The motor/agency half of Craig’s emotion dyad. If the insula is limbic sensory cortex (feeling), the ACC is limbic motor cortex (motivation, agency, behavioural drive): insula + ACC together constitute an emotion. See craig-2002-interoception, craig-2009-anterior-insula, ad-craig.

The evidence for the dyad

• The lamina-i-spinothalamocortical-pathway has a dual projection: to the insula (via VMpo/VMb) and, via an ancillary medial thalamic route (MDvc), to the ACC.
• Their descending projections split along sensory/motor lines: insula → parabrachial (sensory) brainstem regions; ACC → periaqueductal grey (motor) regions.
• The ACC and anterior insula are co-activated in virtually all imaging studies of emotion — the anatomical separation is explained (Craig 2009, Box 1) by their distinct evolutionary origins (ACC from olfactory-guided motor control; insula from homeostatic sensory processing), later linked for integrated autonomic control.

Function

• The ACC signals the urgency/motivation component — e.g., it is selectively activated during the thermal-grill-illusion and correlates with the unpleasantness (not intensity) of pain.
• It supplies the active agent (“the I”) that Craig argues is missing from Damasio’s somatic-marker-hypothesis and that answers a classic criticism of James–Lange (no account of internally generated emotion) — see global-emotional-moment.
• With the insula, amygdala, and hypothalamus it forms the salience-network; the two are interconnected by von-economo-neurons.