Touch and the body: The role of the somatosensory cortex in tactile awareness

This review addresses the role of early sensory areas in the awareness of tactile information in humans. The results of recent studies dealing with this important topic are critically discussed: In particular, we report on evidence from neuropsychology, neurophysiology, neuroimaging, and behavioral experiments that have highlighted the crucial role played by the primary somatosensory cortex (SI) in mediating our awareness of tactile information. Phenomena, such as tactile hallucinations, tactile illusions, the perception of supernumerary limbs, and synaesthesia are also discussed. The research reviewed here clearly shows that the activation of SI is necessary, but not sufficient, for the awareness of touch. On the basis of the evidence outlined here, we propose a neurocognitive model that provides a conceptual framework in which to interpret the results of the literature regarding tactile consciousness.