Self-body recognition is the ability to recognize one’s body parts as one’s own. This ability is impaired in some neuropsychiatric patients. The present chapter reviews symptoms that demonstrate impaired self-body recognition. Several studies have repeatedly shown that the parietal lobe plays an important role in self-body recognition. In particular, the superior parietal lobe is involved in maintaining short-term memory about the self-body image that produces the sense of ownership of one’s body. The right inferior parietal lobule is crucial for detecting discrepancies among multiple afferent sensory inputs, such as the proprioceptive and visual inputs of the body. The authors suggest that temporal consistency among multisensory feedback inputs is important for self-body recognition, which is most likely integrated in the parietal lobe.
TopIntroduction
Self-body recognition is the fundamental human cognitive ability to recognize our body parts as our own. We usually have no difficulty distinguishing our own arm from someone else’s. However, some neuropsychiatric patients have impairment in this ability. Gallagher (2000) argued that self-body recognition can be reduced to two basic subjective senses of the self: the sense of self-ownership and the sense of self-agency. The sense of self-ownership is the feeling that one’s body is one’s own, whereas the sense of self-agency refers to the feeling that one’s body movement is caused by oneself. These two senses are clearly distinguished in active (voluntary) and passive (involuntary) body movements. In an active body movement, both the sense of ownership and the sense of agency are experienced, whereas in a passive body movement, only the sense of ownership is experienced. This sense of ownership is thought to be realized by the integration of multiple sensory feedback sources from one’s own body.
The difference between the senses of ownership and agency lies in whether the internal signal of the motor command (the ‘efference copy’) is available. Self-body recognition is most likely substantiated by a neural process of spatio-temporal integration of bodily visual input, proprioceptive/tactile input, and, if applicable, efference copies of motor commands (and predictions of sensory feedback generated from these). The sense of ownership is considered to emerge mainly from the integration process of visual and proprioceptive/tactile inputs, whereas the sense of agency is based on the integration of the efference copy and reafferent sensory (visual and proprioceptive/tactile) feedback. Previous studies have shown that the temporal contiguity of these signals is crucial for the recognition of one’s own body (Botvinick & Cohen, 1999; Franck et al., 2001; Shimada et al., 2005; Shimada et al., 2009). In particular, the synchrony of visual and tactile/proprioceptive feedback seems important (Armel and Ramachandran, 2003; Franck et al., 2001). Because proprioceptive feedback is specific to oneself and relatively invariant under various circumstances, the visual property that coincides with proprioceptive feedback is likely to result in the perception of one's own body.
In this chapter, I will review some neuropsychiatric disorders that cause self-body recognition to malfunction and discuss the plausible neural mechanism that realizes the sense of self-body.