Understanding Motor Awareness Through Normal and Pathological Behavior

Data on patients with localized brain damage and on neurologically intact subjects show that normal motor control depends on the functionality of a chain of neurobiological events. These events, through the activation of internal representations of the desired, predicted, and actual condition of one’s body with respect to the external world, contribute to the construction of conscious knowledge of voluntary actions and to self-awareness. KEYWORDS—consciousness; awareness; intention; motor system; action; anosognosia; brain damage; hemiplegia Interaction with other individuals and with the environment more generally is mediated by motor actions through which people try to achieve their goals and purposes. Action is generated through a chain of neurobiological events that is often not available to consciousness, but people are usually aware of moving (or not moving) different parts of their bodies. Therefore, people experience motor awareness of actions performed (i.e., the conscious knowledge that, for instance, my hand is moving), as well as intentional attitudes, defined as the felt urge to make a movement that precedes the actual execution of a specific motor act. People also feel a strong sense of controlling their own actions (i.e., the belief that it is I who am moving my hand), designated as the sense of agency. The normal integration between these different aspects of conscious motor control seems to be crucial for the building up of one’s sense of self. When movement control is dramatically impaired, serious consequences for the construction of coherent self-knowledge can be observed. For instance, brain-damaged patients with contralesional hemiplegia (paralysis of the side of the body opposite to the damaged hemisphere) may deny their deficit, claiming that their paralyzed limbs can still move. This denial behavior, which almost always occurs after a right-hemisphere stroke (affecting, as a consequence, the left part of the body), is termed anosognosia (fragments from typical conversations with an anosognosic patient are shown in Box 1; Berti, Làdavas, Stracciari, Giannarelli, & Ossola, 1998). In the present article, we discuss how the description of anosognosic symptoms, integrated with data on normal subjects, can help in understanding the neural bases of motor awareness and self-monitoring.