Neuropsychology of the sense of agency- theoretical and empirical contributions

How do I know that I am the person who is moving? The neuroscience of action shows the existence of specific cognitive processes allowing the organism to refer the cause or origin of an action to its agent (Georgieff & Jeannerod, 1998). This sense of agency has been defined as the sense that I am the one who is causing or generating an action or a certain thought in my stream of consciousness (Gallagher, 2000). As such, one can distinguish actions that are self-generated from those generated by others, giving rise to the experience of a self-other distinction in the domain of action and thus contributing to the subjective phenomenon of self-consciousness. Theoretical and empirical implications of the sense of agency for consciousness, self-consciousness and action will be considered in the present chapter. The main question that the chapter tries to answer is about the causal explanation of action and about the mechanism of conscious control of action implicated on both normal and pathological cases (such as schizophrenia). The investigation of the sense of agency is an increasingly prominent field of research in psychology as well as cognitive neurosciences alike. Recent conceptual developments distinguished between different levels of the sense of agency: separating an implicit level of ‘‘feeling of agency” as opposed to an explicit level of ‘‘judgment of agency”. The first level is thought to be characterized by lower-level, pre-reflective, sensorimotor processes, and the second level by higher-order, reflective or belief-like processes. Sensorimotor processes thought to be characteristic for the feeling level may run outside of consciousness (but may be available to awareness). This is supported by empirical evidence that, for example, minor ‘violations of intended actions or action consequences (i.e., brief temporal delays in sensory feedback) do not necessarily enter awareness (Blakemore & Sirigu, 2003), while neural signatures of such violations can be observed (David et al., 2007). The predominant account on explaining the sense of agency of our own actions is the ‘‘central monitoring theory” or ‘‘comparator model” that postulate a monitoring of central and peripheral signals arising as a consequence of the execution of an action. This theory holds that the (central) efferent signals at the origin of an action are matched with those which result from its execution (the reafferent signals) and that this comparison provides cues about where and when the action originated.