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

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Chapter 8
subliminal exposure to emotional facial expressions leads to increased responses in
expression relevant facial muscles of the observer (Dimberg, Thunberg, and Elmehed,
2000); blocking expression relevant facial muscles results in deficits in the observer’s
ability to correctly categorize the expressions of others (Oberman, Winkielman, and
Ramachandran, 2007); perceiving another person’s facial expressions correlates with
increased activity in similar motor (e.g. inferior frontal gyrus and premotor cortex of
the human mirror system) and somatosensory representations (e.g. primary and
secondary somatosensory cortex) as when the perceiver generates the same emotion
or expression (Hennenlotter et al., 2005; Leslie, Johnsen-Frey, and Grafton, 2004;
Montgomery and Haxby, 2008; van der Gaag, Minderaa, and Keysers, 2007);
transiently disrupting neural activity in the somatosensory cortex disrupts the
observer’s expression recognition abilities (Pitcher, Garrido, Walsh and Duchaine,
2008; Pourtois et al., 2004); and brain damage to somatosensory-related cortices
results in facial expression recognition deficits (Adolphs, Damasio, Tranel, Cooper,
and Damasio, 2000).
While these findings converge on a key role for sensorimotor simulation in
facial expression recognition, a number of unanswered questions remain. For
example, recent findings indicate that right somatosensory-related cortices play a
pivotal role in facial expression recognition (Adolphs et al., 2000; Pitcher et al., 2008;
Pourtois et al., 2004), but the extent to which neural activity in cortical regions
involved in other aspects of sensorimotor simulation (e.g. simulation of motor as
opposed to somatic consequences of the perceived emotion) are also critical for facial
expression recognition remains unclear. Functional brain imaging indicates a role of
neural activity in both somatosensory and motor regions of the cortex in expression
recognition (Carr, Iacoboni, Dubeau, Mazziotta, and Lenzi, 2003; Hennenlotter et al.,