A Double Dissociation in Deafferented Patients

INTRODUCTION The concept and term of "Body Image" (l'image de soi, Lhermitte, 1937) has frequently been used interchangeably in neurological and psychological studies with that of "Body Schema" (Körperschema) (Schilder, 1935) thus leading to enduring methodological and conceptual confusions in various fields. In a recent review, Shaun Gallager (1992) stressed the serious implications that the terminological and conceptual confusions related to body image and body schema have had for the study of body experience and personality in the psychoanalytical and phenomenological literature. He rightly points to the relationship between consciousness and these body concepts as the main unresolved issue in this controversial field. In suggesting that the first step in working out a distinction between body image and body schema is to distinguish between a conscious awareness of one's own body and a non conscious performance of the body, Gallager meets the criticisms that we addressed nearly 20 years earlier (following to Oldfield, & Zangwill, 1941/42) to the neurologists in a meeting devoted to the problem of selfconsciousness (Paillard, 1975). We vigorously denounced the perduring confusion between these basic concepts in the neurological and psychological literature in spite of the very clear distinction that was initially made by Head and Holmes (1912), between: 1) the " Body Schema " as " A combined standard against which all subsequent changes of posture are measured ... before the changes of posture enter consciousness" 2) the " Superficial schema " as a central mapping of somatotopic information derived from the tactile information and 3) the " Body Image " as an internal representation in the conscious experience of visual, tactile and motor information of corporal origin. We also appealed to expanding efforts for establishing the biological identity and validity of such a distinction. At that time, widespread interest was generated by the discovery of the existence of " two visual systems ", one for object perception and one for spatial localisation. The study initially separated the role of collicular structures in orientation and localisation from that of cortical areas in the perceptual discrimination and categorisation of visual forms. It was later established by neuroanatomical, neurophysiological and neuropsychological studies (Ungerleider & Mishkin, 1982) that both systems were corticalized in primates and man leading to the now classical functional segregation between the "what" and "where" systems with their underlying neural networks in the temporal and the parietal cortex respectively. We then proposed (Paillard, 1975, 1980) …