Cerebellum and human evolution: A comparative and information theory perspective

Abstract

The cerebral cortex occupies a prominent place in the social brain hypothesis, which posits that human brain evolution has largely been shaped by social interactions in an increasingly more complex group structure and the associated cognitive tasks at the cerebral cortical level. Social interactions are adaptive behaviors in responses to selection pressure and are also the sources of selection pressure. Complex social interactions both require and foster communication. To communicate and transmit information, individual members of the group must acquire a common language of communication, most certainly via imitation. Hurley has recently proposed a shared circuits model for imitation. This model has implicated many cerebral cortical structures, including the mirror neuron system. In this model, a basic element supporting complex behavior leading to imitation is active perception. Neuroplasticity mechanisms in the cerebellum and particularly in the neocerebellum may be the major provider of this critical function such that active perception constitutes part of the cerebellar function of procedural learning, or vice versa. In this chapter, the role of the cerebellum in the evolution of complex behaviors is examined. Data from fish, amphibian, reptile, bird, and mammal are summarized to show a phylogenetic expansion of the neocerebellum to interact with the neocortex. Within mammals, there is a progressive increase in the capacity of the cerebellum to code and process information from mouse, rat, cat, rhesus monkey, and human. The increasingly expanding interactions between the cerebral cortex and the cerebellum operating with a high information coding and processing capacity may uniquely contribute to the acquisition of complex behavior including language and communication for social interaction - a major hallmark of human evolution.