Figure 6.

Forward models and prediction. (A) To predict the sensory consequences of actions, a forward model is implemented in the motor cerebellum by interacting with the motor cortex and using efference copies of motor commands, which reach the cerebellum through the mossy fibers (MF) originating in the pontine nuclei (Pons). The difference between the predicted and actual motor outcome (prediction errors) reaches the cerebellum through the climbing fibers (CF) originating in the inferior olive (IO). (B) Because the uniformity of cellular organization across the cerebellar cortex suggests identity in the computations, the cerebellar forward models may even provide computational mechanisms for cognitive/emotional processes. The cerebellum models interoceptive and cognitive prediction errors, given its connectivity with the cingulate cortex, hypothalamus, and amygdala, as well as with frontal and parietal cortices via the thalamus (Th). A copy of the output of the prefrontal and frontal cortex is sent via the pontine nuclei to the interconnected cerebellar lobules. The predictions generated from cerebellar lobules are transmitted from the Purkinje cells via the deep cerebellar nuclei (DCN) and the thalamus back to the same neocortical areas. Predicted and actual consequences of the process copied by these cerebellar lobules are compared in the inferior olive, and any mismatch between the two are fed via climbing fibers to the cerebellar cortex as an error signal. Long-term depression is triggered at the parallel fiber to Purkinje cell synapses, updating the internal model.