FIGURE 1.

A model of tool-body assimilation. In the model, the visual cortex (VC) performs basic visual processing; the parietal cortex (PC) extracts affordances based on body/world relations and encodes abstract action goals; the pre-motor cortex (PMC) prepares actions based on more specific action goals; the pre-frontal cortex (PFC) encodes the agent’s ultimate goals based on context and internal homeostatic regulations, and on this basis contributes to form action goals in the PMC and the PC; cortico-cerebellar (Cer) loops simulate body-world, dynamics; cortico-basal ganglia (BG) loops underlie action and affordance selection processes. (A–C) represent a possible progression of development of representations from body actions, to tool-mediated actions and words-as-tool actions, all relying on the same macro brain areas and on partially overlapping local neural modules (cell assemblies). Multiple PC-PMC arrows represent multiple affordance-action options and the black arrow the most active within these.