Mirror-touch synaesthesia: the role of shared ... - UCL Discovery

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Chapter 5
activation of expression relevant muscles impairs expression recognition (Oberman,
Winkielman, and Ramachandran, 2007); and that perceiving another person’s facial
expressions recruits similar premotor and somatosensory representations as when the
perceiver generates the same emotion or expression (Carr, Iacoboni, Dubeau,
Mazziotta, and Lenzi, 2003; Hennenlotter et al., 2005; Montgomery and Haxby, 2008;
van der Gaag, Minderaa, and Keysers, 2007; Winston, O’Doherty, and Dolan, 2003).
Further, neuropsychological findings indicate that focal brain damage to right
somatosensory cortices is associated with expression recognition deficits (Adolphs,
Damasio, Tranel, Cooper, and Damasio, 2000), and transcranial magnetic stimulation
findings demonstrate the necessity of the right somatosensory cortex for facial
expression recognition abilities in healthy adults but not face identity recognition
(Pitcher, Garrido, Walsh and Duchaine, 2008). These findings imply that purely
visual face-processing mechanisms interact with sensorimotor representations to
facilitate expression recognition. This thought to differ to facial identity recognition,
in which there is no clear indication of how one could simulate another’s identity
(Calder and Young, 2005).
While much has been learnt from studies involving a disruption of simulation
mechanisms, an alternative approach is to consider whether facilitation of these
mechanisms promotes expression recognition. One example of facilitated
sensorimotor simulation is the case of mirror-touch synaesthesia (Blakemore, Bristow,
Bird, Frith, and Ward, 2005). As noted previously, in mirror-touch synaesthesia,
simply observing touch to others elicits a conscious tactile sensation on the
synaesthete’s own body. Functional brain imaging indicates that this variant of
synaesthesia is linked to heightened neural activity in a network of brain regions
which are also activated in non-synaesthetic control subjects when observing touch to