Giovanni Berlucchi Æ Salvatore M. Aglioti
Corporeal awareness is a difficult concept which refers to perception, knowledge and evaluation of one’s own body as well as of other bodies. We discuss here some controversies regarding the significance of the concepts of body schema and body image, as variously entertained by different authors, for the understanding of corporeal awareness, and consider some newly proposed alternatives. We describe some recent discoveries of cortical areas specialized for the processing of bodily forms and bodily actions, as revealed by neuroimaging, neurophysiological, and lesion studies. We further describe new empirical and theoretical evidence for the importance of interoception, in addition to exteroception and proprioception, for corporeal awareness, and discuss how itch, a typical interoceptive input, has been wrongly excluded from the classic concept of the proprioceptive–tactile body schema. Finally, we consider the role of the insular cortex as the terminal cortical station of interoception and other bodily signals, along with Craig’s proposal that the human insular cortex sets our species apart from other species by supporting consciousness of the body and the self. We conclude that corporeal awareness depends on the spatiotemporally distributed activity of many bodies in the brain, none of which is isomorphic with the actual body. Keywords Body schema _ Body image _Corporeal awareness _ Extrastriate body area _ Insula _Itch
Awareness of one’s own body is a very special form of cognition, and the scientific study of its experiential components and physiological underpinnings is fraught with considerable theoretical and practical difficulties. From a neuroscientific perspective one can assume that the problem boils down to understanding what kind of messages the brain receives from the rest of the body, and how such messages are integrated by appropriate cerebral mechanisms into organized experiences of one’s body and oneself. However, such mechanisms and experiences are also likely to be involved in the ability to perceive and know the structure and movements of the bodies of other individuals, in order to understand their actions and to interpret their gestures for social communication. One can thus postulate the existence of a cognitive category for the human body whose components include one’s own body as well as the bodies of other humans. Nearly a century ago the British neurologists Head and Holmes (1911/12) attempted to tackle the basic problem of how the brain processes its own body by emphasizing the primary role of proprioception and touch, and by proposing one body schema for the appreciation of posture or passive movement and another body schema for the localization of stimulated spots on the skin. In their conception, schemas or schemata are instant-by-instant proprioceptive and surface‘‘plastic models of oneself’’ against which all subsequent changes in posture, movement and tactile stimulation can be measured.