Perception is not a direct image of sensorial input, but a hypothesis
explaining sensorial information. The brain hallucinates reality. The ability to infer the
causes of sensations requires an internal generative model, known as Predictive
Coding. The brain tries to minimize prediction error between inputs and models about
the causes of these inputs. Top-down connections of the brain convey predictions,
whereas bottom-up connections transmit predictive errors. Expectations, from the
perspective of Predictive Coding, refer to representations of causes encoded at each
level. The same principles apply to interoception. The architecture of the insula allows
for successively higher re-representations of interoceptive information, homeostatic
significance, emotional salience and hedonic potential. The anterior insula integrates
bottom-up interoceptive predictive error with high-level cortical predictions and sends
interoceptive predictions to visceral systems. Generative models depend on actions.
They actively map from hidden causes to sensory consequences. Perception
corresponds to the inverse mapping, from sensations to hidden causes at higher levels
of relational abstraction. The experience of body ownership fits a model of conscious
selfhood based on interoceptive Predictive Coding underlying multisensorial
integration. Predictive Coding supports a subject-centric view whereby actions not only
lie at the basis of consciousness, but also provide the building elements of the subject
itself. Neural correlates of consciousness represent what the subject is doing. The
emergence of abstract phenomenal objects as guides to global adaptive behaviors
favors the transition to phenomenological heuristics. Natural environments are
characterized by low predictability, small sample sizes relative to the number of
available cues, and interdependency among cues. Models based on heuristics are
adaptive because predictive-error is difficult to calculate for global actions in an
uncertain world.
Keywords: Active Inference, Bottom-Up, Brain Operations, Computational
Hierarchy, Cortical Development, Embodied Abstractions, EPIC, Expectation,
Feedback, Feedforward, Functional Connectivity, Generative Model, Heuristics,
Interoception, Insular Cortex, Perception, Phenomenal Consciousness, Predictive
Coding, Predictive Error, Predictions, Systematic Cortical Variation, Systems 1
and 2, Top-Down, Unified Stream of Consciousness, Winner-Take-All.
