Prevalence, characteristics and a neurocognitive model of mirror-touch synaesthesia

In so-called ‘mirror-touch synaesthesia’, observing touch to another person induces a subjective tactile sensation on the synaesthete’s own body. It has been suggested that this type of synaesthesia depends on increased activity in neural systems activated when observing touch to others. Here we report the first study on the prevalence of this variant of synaesthesia. Our findings indicate that this type of synaesthesia is just as common, if not more common than some of the more frequently studied varieties of synaesthesia such as grapheme-colour synaesthesia. Additionally, we examine behavioural correlates associated with the condition. In a second experiment, we show that synaesthetic experiences are not related to somatotopic cueing—a flash of light on an observed body part does not elicit the behavioural or subjective characteristics of synaesthesia. Finally, we propose a neurocognitive model to account for these characteristics and discuss the implications of our findings for general theories of synaesthesia.

[1]  S-J Blakemore,et al.  Somatosensory activations during the observation of touch and a case of vision-touch synaesthesia. , 2005, Brain : a journal of neurology.

[2]  A. Craig.  How do you feel? Interoception: the sense of the physiological condition of the body , 2002, Nature Reviews Neuroscience.

[3]  M. Tanaka,et al.  Coding of modified body schema during tool use by macaque postcentral neurones. , 1996, Neuroreport.

[4]  Jamie Ward,et al.  Synaesthesia: The Prevalence of Atypical Cross-Modal Experiences , 2006, Perception.

[5]  N. Kanwisher,et al.  A Cortical Area Selective for Visual Processing of the Human Body , 2001, Science.

[6]  H. Scholte,et al.  Increased structural connectivity in grapheme-color synesthesia , 2007, Nature Neuroscience.

[7]  Vittorio Gallese,et al.  The Sense of Touch: Embodied Simulation in a Visuotactile Mirroring Mechanism for Observed Animate or Inanimate Touch , 2008, Journal of Cognitive Neuroscience.

[8]  M. Mesulam,et al.  Insula of the old world monkey. II: Afferent cortical input and comments on the claustrum , 1982, The Journal of comparative neurology.

[9]  Jamie Ward,et al.  Non-random associations of graphemes to colours in synaesthetic and non-synaesthetic populations , 2005, Cognitive neuropsychology.

[10]  Alison J. Wiggett,et al.  Functional MRI analysis of body and body part representations in the extrastriate and fusiform body areas. , 2007, Journal of neurophysiology.

[11]  M. Goldberg,et al.  Ventral intraparietal area of the macaque: congruent visual and somatic response properties. , 1998, Journal of neurophysiology.

[12]  J. Bradshaw,et al.  Mechanisms underlying embodiment, disembodiment and loss of embodiment , 2008, Neuroscience & Biobehavioral Reviews.

[13]  Jamie Ward,et al.  Lexical-gustatory synaesthesia: linguistic and conceptual factors , 2003, Cognition.

[14]  Tony Ro,et al.  Visually induced feelings of touch , 2006, Brain Research.

[15]  O. Blanke,et al.  Out-of-body experience and autoscopy of neurological origin. , 2004, Brain : a journal of neurology.

[16]  E. Làdavas,et al.  Viewing a Face (Especially One's Own Face) Being Touched Enhances Tactile Perception on the Face , 2008, Psychological science.

[17]  V. Ramachandran,et al.  Synaesthesia? A window into perception, thought and language , 2001 .

[18]  Avishai Henik,et al.  Small is bright and big is dark in synaesthesia , 2007, Current Biology.

[19]  O. Blanke,et al.  Neural Basis of Embodiment: Distinct Contributions of Temporoparietal Junction and Extrastriate Body Area , 2006, The Journal of Neuroscience.

[20]  S. Baron-Cohen,et al.  Hearing Words and Seeing Colours: An Experimental Investigation of a Case of Synaesthesia , 1987, Perception.

[21]  J. Ward,et al.  Non-random associations of graphemes and colour in the synaesthetic and normal populations , 2005 .

[22]  G. Holmes,et al.  Sensory disturbances from cerebral lesions , 1911 .

[23]  Peter Brugger,et al.  Reflective mirrors: Perspective-taking in autoscopic phenomena , 2002, Cognitive neuropsychiatry.

[24]  P. Garthwaite,et al.  Investigation of the single case in neuropsychology: confidence limits on the abnormality of test scores and test score differences , 2002, Neuropsychologia.

[25]  W. Schofield,et al.  Do Children Find Movements Which Cross the Body Midline Difficult? , 1976 .

[26]  A. Sirigu,et al.  Multiple representations contribute to body knowledge processing. Evidence from a case of autotopagnosia. , 1991, Brain : a journal of neurology.

[27]  J. Decety,et al.  Effect of subjective perspective taking during simulation of action: a PET investigation of agency , 2001, Nature Neuroscience.

[28]  S. Kastner,et al.  Two hierarchically organized neural systems for object information in human visual cortex , 2008, Nature Neuroscience.

[29]  K. Zilles,et al.  Polymodal Motion Processing in Posterior Parietal and Premotor Cortex A Human fMRI Study Strongly Implies Equivalencies between Humans and Monkeys , 2001, Neuron.

[30]  Christopher T. Lovelace,et al.  Mechanisms of synesthesia: cognitive and physiological constraints , 2001, Trends in Cognitive Sciences.

[31]  Istvan Molnar-Szakacs,et al.  Self-face recognition activates a frontoparietal “mirror” network in the right hemisphere: an event-related fMRI study , 2005, NeuroImage.

[32]  Carol L. Colby,et al.  Action-Oriented Spatial Review Reference Frames in Cortex , 1998 .

[33]  H. Branch Coslett,et al.  Evidence for a Disturbance of the Body Schema in Neglect , 1998, Brain and Cognition.

[34]  Jamie Ward,et al.  A comparison of lexical-gustatory and grapheme-colour synaesthesia , 2005, Cognitive neuropsychology.

[35]  G. Fink,et al.  Cerebral Representation of One’s Own Past: Neural Networks Involved in Autobiographical Memory , 1996, The Journal of Neuroscience.

[36]  G. Bargary,et al.  Synaesthesia and cortical connectivity , 2008, Trends in Neurosciences.

[37]  Jonathan S. A. Carriere,et al.  When 3 is a Jerk and E is a King: Personifying Inanimate Objects in Synesthesia , 2007, Journal of Cognitive Neuroscience.

[38]  Jamie Ward,et al.  Sound-Colour Synaesthesia: to What Extent Does it Use Cross-Modal Mechanisms Common to us All? , 2006, Cortex.

[39]  Jason B. Mattingley,et al.  Anomalous perception in synaesthesia: A cognitive neuroscience perspective , 2002, Nature Reviews Neuroscience.

[40]  Edward M. Hubbard,et al.  Neurocognitive Mechanisms of Synesthesia , 2005, Neuron.

[41]  G. Rizzolatti,et al.  The mirror-neuron system. , 2004, Annual review of neuroscience.

[42]  Francis McGlone,et al.  Cognitive influences on the affective representation of touch and the sight of touch in the human brain. , 2008, Social cognitive and affective neuroscience.

[43]  Shaun Gallagher,et al.  Body Schema and Intentionality , 1995 .

[44]  A. Maravita,et al.  Tools for the body (schema) , 2004, Trends in Cognitive Sciences.

[45]  Istvan Molnar-Szakacs,et al.  rTMS to the right inferior parietal lobule disrupts self-other discrimination. , 2006, Social cognitive and affective neuroscience.

[46]  Vincent Walsh,et al.  Synaesthesia and cortical connections: cause or correlation? , 2008, Trends in Neurosciences.

[47]  A. Marcel,et al.  The body and the self , 1995 .

[48]  O. Blanke,et al.  Neuropsychology: Stimulating illusory own-body perceptions , 2002, Nature.

[49]  E. Franz,et al.  Brain and cognitive processes of imitation in bimanual situations: Making inferences about mirror neuron systems , 2007, Brain Research.

[50]  Y. Lamarre,et al.  Unmyelinated tactile afferents signal touch and project to insular cortex , 2002, Nature Neuroscience.

[51]  P. Haggard.  Just seeing you makes me feel better: Interpersonal enhancement of touch , 2006, Social neuroscience.

[52]  M. Iacoboni,et al.  The self and social cognition: the role of cortical midline structures and mirror neurons , 2007, Trends in Cognitive Sciences.

[53]  Anina N. Rich,et al.  A systematic, large-scale study of synaesthesia: implications for the role of early experience in lexical-colour associations , 2005, Cognition.

[54]  Julia Simner,et al.  Ordinal Linguistic Personification as a Variant of Synesthesia , 2007, Journal of Cognitive Neuroscience.

[55]  M. Mesulam,et al.  Insula of the old world monkey. III: Efferent cortical output and comments on function , 1982, The Journal of comparative neurology.

[56]  Lindsey J. Powell,et al.  My body or yours? The effect of visual perspective on cortical body representations. , 2006, Cerebral cortex.

[57]  P. Downing,et al.  Selectivity for the human body in the fusiform gyrus. , 2005, Journal of neurophysiology.

[58]  Yasuhiro Maeda,et al.  Cortical mechanisms of visual self-recognition , 2005, NeuroImage.

[59]  Jason B. Mattingley,et al.  Synaesthesia: an Overview of Contemporary Findings and Controversies , 2006, Cortex.

[60]  Avishai Henik,et al.  Induced Cross-Modal Synaesthetic Experience Without Abnormal Neuronal Connections , 2009, Psychological science.

[61]  Jamie Ward,et al.  Is Synaesthesia an X-Linked Dominant Trait with Lethality in Males? , 2005, Perception.

[62]  P. Benson,et al.  Recognizing one's own face , 2001, Cognition.

[63]  Simon Baron-Cohen,et al.  Synaesthesia: Prevalence and Familiality , 1996, Perception.

[64]  Emiliano Macaluso,et al.  Multimodal spatial representations in the human parietal cortex: evidence from functional imaging. , 2003, Advances in neurology.

[65]  J. Ward,et al.  Mirror-touch synesthesia is linked with empathy , 2007, Nature Neuroscience.

[66]  Steven C.R. Williams,et al.  Implications of synaesthesia for functionalism - Theory and experiments , 2002 .

[67]  Avishai Henik,et al.  Can synaesthesia research inform cognitive science? , 2007, Trends in Cognitive Sciences.

[68]  L. Fogassi,et al.  A Touching Sight SII/PV Activation during the Observation and Experience of Touch , 2004, Neuron.