text: Figure 1. A schematic illustration of a hierarchical active inference model. This model links (exteroceptive, interoceptive, and proprioceptive) 
  sensations at lower levels with multimodal models of hidden bodily states, such as fatigue and hunger, at intermediate levels, and finally with 
  temporally extended, integrative models of the embodied self at the higher hierarchical level. In this schematic, following predictive coding (Rao and 
  Ballard 1999, Friston 2005), black and red circles represent neural units that encode predictions and prediction errors, respectively. The levels are 
  reciprocally connected, so predictions are propagated from the top-down (black edges) and prediction errors from the bottom-up (red edges). Finally, 
  the pink triangles indicate a mechanism of precision gating (or gain control) of prediction error units, which determines their relative influence on 
  units encoding predictions. At a neurobiological level, prediction and prediction error units could be mapped to deep and superficial pyramidal cells in 
  cortical hierarchies, whereas expected precision could be linked to neuromodulatory input. The elements of the generative model shown do not need 
  to map one-to-one to specific brain areas or networks but are plausibly distributed across many of them. However, as a first approximation, the lower 
  and intermediate layers of the generative model could be linked to brain networks that process unimodal information (e.g. sensory cortices for 
  exteroceptive information) and multimodal association areas, respectively. The highest level of the generative model could be linked to brain networks 
  that process information about the self, such as the insular cortex, the anterior cingulate cortex, and the medial prefrontal cortex. See Parr et al. 
  (2022) for details about hierarchical generative models supporting adaptive regulation and allostasis and Barrett and Simmons (2015) for their 
  putative neuronal underpinnings. See online article for colored version of this figure. 