Editorial: Body Representations, Peripersonal Space, and the Self: Humans, Animals, Robots
Matej Hoffmann, Pablo Lanillos, Lorenzo Jamone, Alexandre Pitti, Eszter Somogyi · Frontiers in Neurorobotics · 2020
The presence of various “body maps” in the brain has fascinated scientists and the general public alike, spurred by the account of Head and Holmes (1911) and the discovery of the somatotopic representations (the “homunculi”) in the primary motor and somatosensory cortices of primates (Leyton and Sherrington, 1917; Penfield and Boldrey, 1937). Neurological conditions and accounts of a whole range of illusions regarding own body perception (e.g., rubber hand illusion, out-of-body experience, apparition) generated both seminal research articles (e.g., Botvinick and Cohen, 1998; Lenggenhager et al., 2007) and public interest. The attention devoted to the representations of the body in the brain has also led to numerous attempts at describing or defining them and proposals of a variety of concepts, such as superficial and postural schema (Head and Holmes, 1911), body schema, body image (Paillard, 1999), corporeal schema, etc. One characteristic common to all these representations is their multimodal nature: they dynamically integrate information from different sensory modalities (visual, tactile, proprioceptive, vestibular, auditory), not excluding motor information (Azañón et al., 2016). However, the concepts of body schema, body image, and many others are umbrella notions for a range of observed phenomena rather than a result of identification of specific mechanisms. The field is thus in a somewhat “chaotic state of affairs” (Berlucchi and Aglioti, 2009), with limited convergence to a common view (Graziano and Botvinick, 2002; Holmes and Spence, 2004). Next to “body space,” the space immediately surrounding the body is called peripersonal space. There are two notions associated with this term: (i) a safety margin around the body, and (ii) space within our reach. They may be supported by distinct neuronal substrates—see Cléry et al. (2015) for a survey. Furthermore, it is not clear to what extent the representation of the “body space” and the space around it are overlapping. They may be “two labels for the same concept” (Cardinali et al., 2009) or rely on a unified representation (Canzoneri et al., 2013). Alternatively, others amass evidence suggestive of their dissociation (Bassolino et al., 2015).