Predictive processing framework. Starting with initial conditions in the body and in the world (T0), the brain is thought to continually predict forward in time (T1), preparing changes in the body’s internal systems to support upcoming motor actions. Efferent copies of these motor and visceromotor preparations function as their predicted sensory consequences, cascading to sensory systems to modulate the firing of sensory neurons in advance of incoming sensory inputs. Sensory inputs from the body and the world are continuously compared to prediction signals. If different, prediction errors are sent to update the brain’s internal model for future occasions. This framework is based on a structural model of cortico-cortical connections whereby predictions flow from less to more laminated (i.e., layered) cortices (‘feedback connections’), whereas prediction errors flow in the opposite direction (‘feedforward connections’)155,156. This structural model is consistent with a gradient- but not module-based organization scheme for intrinsic connectivity. This is because the whole brain is thought to participate in predictive processing, not by separating into mental modules, but by operating on a continuous two-way hierarchy. In the feedback direction, abstract predictions are unpacked into particular sensory simulations; at the same time in the feedforward direction, sensory information is compressed to be integrated with the brain’s internal model (see review in7). Figure adapted from104.