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Abstract:
Text comprehension requires inference processes for bridging
gaps between successive sentences. In neuropsychological and brain
imaging studies, these processes have been ascribed to the right
hemisphere. Previously, we presented data from an event-related,
whole-head fMRI study that did not support this proposal (Ferstl
& von Cramon, 2000). When the coherence of visually presented
sentence pairs was to be judged, we found regions in the left
fronto-median wall and in the left retrosplenial / precuneal cortex
to be activated more strongly for coherent than for incoherent
sentence pairs. To replicate and confirm these results, we
conducted two further studies. First, we tested whether the fMRI
results were modality specific by presenting the sentences
auditorily to 12 participants. The results largely replicated those
of the reading study. Futhermore, a combination of the two fMRI
studies allowed to compare and contrast the results for 24
participants. Second, we used the paradigm to test a sample of 26
brain-injured patients. Patients with lesions involving left-sided,
bilateral or right-sided prefrontal regions, as well as left-sided
temporal regions were compared to a patient control group. The
results converged on the previous conclusions: Only those patients
whose lesions reached into left-frontal regions had difficulties
with the coherence judgment task. This combination of methodologies
enables to further delineate the role of frontal brain regions
during language comprehension.
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