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Regionally specific cortical lateralization of abstract and concrete verb processing: Magnetic mismatch negativity study
The neural underpinnings of processing concrete and abstract semantics remain poorly understood. Previous
fMRI studies have shown that multimodal and amodal neural networks respond differentially to different semantic
types; importantly, abstract semantics activates more left-lateralized networks, as opposed to more
bilateral activity for concrete words. Due to the lack of temporal resolution, these fMRI results do not allow to
easily separate language- and task-specific brain responses and to disentangle early processing stages from later
post-comprehension phenomena. To tackle this, we used magnetoencephalography (MEG), a time-resolved
neuroimaging technique, in combination with a task-free oddball mismatch negativity (MMN) paradigm, an
established approach to tracking early automatic activation of word-specific memory traces in the brain. We
recorded the magnetic MMN responses in 30 healthy adults to auditorily presented abstract and concrete action
verbs to assess lateralization of word-specific lexico-semantic processing in a set of neocortical areas. We found
that MMN responses to these stimuli showed different lateralization patterns of activity in the upper limb motor
area (BA4) and parts of Broca’s area (BA45/BA47) within ~100–350 ms after the word disambiguation point.
Importantly, the greater leftward response lateralization for abstract semantics was due to the lesser involvement
of the right-hemispheric homologues, not increased left-hemispheric activity. These findings suggest differential
region-specific involvement of bilateral sensorimotor systems already in the early automatic stages of processing
abstract and concrete action semantics