Predictive coding accounts of shared representations in parieto-insular networks Hiroaki Ishida a,b,n,1 , Keisuke Suzuki c,d,1 , Laura Clara Grandi e a Istituto Italiano di Tecnologia (IIT), Brain Center for Social and Motor Cognition (BCSMC), Parma, Italy b Frontal Lobe Function Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan c Sackler Center for Consciousness Science, University of Sussex, Brighton, UK d School of Informatics and Engineering, University of Sussex, Brighton, UK e Department of Neuroscience, Unit of Physiology, Parma University, Parma, Italy article info Available online 24 October 2014 Keywords: Multisensory integration Sensory-motor integration Body representation Parietal cortex Secondary somatosensory cortex Insular cortex Shared body representation Predictive coding Social touch Mirror neurons abstract The discovery of mirror neurons in the ventral premotor cortex (area F5) and inferior parietal cortex (area PFG) in the macaque monkey brain has provided the physiological evidence for direct matching of the intrinsic motor representations of the self and the visual image of the actions of others. The existence of mirror neurons implies that the brain has mechanisms reflecting shared self and other action representations. This may further imply that the neural basis self-body representations may also incorporate components that are shared with other-body representations. It is likely that such a mechanism is also involved in predicting other's touch sensations and emotions. However, the neural basis of shared body representations has remained unclear. Here, we propose a neural basis of body representation of the self and of others in both human and non-human primates. We review a series of behavioral and physiological findings which together paint a picture that the systems underlying such shared representations require integration of conscious exteroception and interoception subserved by a cortical sensory-motor network involving parieto-inner perisylvian circuits (the ventral intraparietal area [VIP]/inferior parietal area [PFG]-secondary somatosensory cortex [SII]/posterior insular cortex [pIC]/anterior insular cortex [aIC]). Based on these findings, we propose a computational mechanism of the shared body representation in the predictive coding (PC) framework. Our mechanism proposes that processes emerging from generative models embedded in these specific neuronal circuits play a pivotal role in distinguishing a self-specific body representation from a shared one. The model successfully accounts for normal and abnormal shared body phenomena such as mirror-touch synesthesia and somatoparaphrenia. In addition, it generates a set of testable experimental predictions. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction In the setting of non-verbal communication in human and non- human primates, several studies have proposed the existence of a neural mechanism (mirror mechanism [MM]) enabling a basic and direct form of action recognition of others (Rizzolatti and Sinigaglia, 2010). The evidence implies that brains contain representations of bodies of others, as well as the body of the self (self-body). Additional evidence suggests that this mechanism generalizes beyond action observation to other domains including touch and emotional feelings (Singer and Lamm, 2009; Keysers et al., 2010). In line with this idea, a growing number of human brain imaging and physiological studies demonstrate that parieto-frontal circuits are crucial in instantiating shared aspects of self- and other-body representations (Jackson and Decety, 2004; Gallese and Sinigaglia, 2011; de Vignemont, 2014; Rizzolatti et al., 2014). In the present article, we focus on the neural basis of shared body representation within the parieto-inner perisylvian (ventral intraparietal area [VIP]/inferior parietal area [PF/PFG]-secondary somatosensory cortex [SII]/insular cortex) circuits in both humans and non-human primates. First, we discuss the shared body representation in the parieto-premotor networks (Fig. 1). The net- works are involved in both multisensory (visual, somatosensory, auditory, and vestibular inputs) and sensory-motor integrations (Murata and Ishida, 2007; Blanke, 2012). Visuo-tactile integration is of great importance in organizing self-body recognition, which is Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/neuropsychologia Neuropsychologia http://dx.doi.org/10.1016/j.neuropsychologia.2014.10.020 0028-3932/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author at: Frontal Lobe Function Project, Tokyo Metropolitan Institute of Medical Science, Kamikitazawa 2-1-6, Setagaya-ku, Tokyo 156-8506, Japan. E-mail address: ishida-hr@igakuken.or.jp (H. Ishida). 1 H.I. and K.S. contributed equally to this work. Neuropsychologia 70 (2015) 442–454