Physiology of Volition

Abstract

The idea of free will is a conscious awareness of the brain concerning the nature of the movement that it produces. There is no evidence for it to be a driving force in movement generation. This review considers the physiology of movement generation and how the concepts of willing and agency might arise. Both the anatomical substrates and the timing of events are considered. Movement initiation and volition are not necessarily linked, and one line of evidence comes from consideration of patients with disorders of volition. Movement is generated subconsciously, and the conscious sense of willing the movement comes later, but the exact time of this event is difficult to assess because of the potentially illusory nature of introspection. The evidence suggests that movement is initiated in frontal lobe, particularly the mesial areas, and the sense of volition arises as the result of a corollary discharge from premotor and motor areas likely involving the parietal lobe. Agency probably involves a similar region in the parietal lobe and requires both the sense of volition and movement feedback.