Cerebellar sense of self and sense of agency

The idea of the cerebellar self provides a framework from which to explore cerebellar function, starting with the insight this provides for human psychotic states that fail to distinguish ‘self’ from ‘other’. One key task of cerebellar adaptive filters is to provide predictions of the consequences of our actions, called forward models, such as the sensory consequences of movements we make. For example, it is well known that an external tickle is more ticklish than self-tickle, an effect that can be attributed to the cerebellar attenuation of predictable input. Interestingly, people with some forms of psychoses do not experience the same difference, clearly implicating an underlying cerebellar dysfunction. A role for the cerebellar sense of self also extends to that compelling, but fragile, experience of controlling actions in the outside world. This is called our sense of agency, and it too depends on a match between expectations and eventualities.