History of neuroscience of self-initiated action and volition: recent developments and paradigm shift

For decades several studies have been trying to find the source of ‘intention’ in the brain. Historically, we have two landmark studies.The first one, by Kornhuber and Deecke (1965) lead to the discovery of the readiness potential (BP), a slow buildup of neural activity preceding un-cued, “self-initiated” movements, whose location was identified in the preSMA and SMA areas of the brain. This buildup has been observed using both invasive and non- invasive neural recordings and in both vertebrate and invertebrate species. Around 20 years later, the experiment by Benjamin Libet (1983), showed a lag between the subjective time of the urge or intention to move and the neural decision to act represented by this electrophysiological signal of movement preparation, opening up a still running debate concerning the unawareness of neuronal mechanisms underlying free choices. In this panorama, the research on self-initiated action has so far proceeded under the assumption that this buildup reflects the beginning of a causal process of “planning and preparation for movement”. Recent developments in the field seriously challenge this assumption and have opened the door to a paradigm shift in this area of research. We will review the modern history of research on self-initiated movement and volition with a focus on these recent developments, suggesting how the introduction of formal computational models (accumulator or bounded-integration models) for the study of volition is playing a major role in this change of perspective.