  Simulation models of facial expressions suggest that posterior visual areas
and brain areas underpinning sensorimotor simulations might interact to improve
facial expression processing. According to these models, facial mimicry may
contribute to the visual processing of facial expressions by influencing early
stages. The aim of the present study was to assess whether/how early
sensorimotor simulation influences early stages of face processing. A secondary
aim was to investigate the relationship between alexithymic traits and
sensorimotor simulation. We monitored P1 and N170 components of the
event-related potentials (ERP) in participants performing a fine discrimination
task of facial expressions while implementing an animal discrimination task as
control condition. In half of the experiment, participants could freely use
their facial mimicry whereas in the other half, they had their facial mimicry
blocked by a gel. Our results revealed that, on average, both P1 and N170 ERP
components were not sensitive to mimicry manipulation. However, when taking
into account alexithymic traits, a scenario corroborating sensorimotor
simulation models emerged, with two dissociable temporal windows affected by
mimicry manipulation as a function of alexithymia levels. Specifically, as a
function of mimicry manipulation, individuals with lower alexithymic traits
showed modulations of the P1 amplitude, while individuals with higher
alexithymic traits showed modulations of the later N170). Furthermore,
connectivity analysis at the scalp level suggested increased connectivity
between sensorimotor and extrastriate visual regions in individuals with lower
alexithymic traits compared to individuals with higher alexithymic traits.
Overall, we interpreted these ERPs modulations as compensative visual
processing under conditions of interference on the sensorimotor processing.
