The role of coherence and cohesion in text comprehension: an event-relatedfMRI study

Text processing requires inferences for establishing coherence between succ essive sentences. In neuropsychological studies and brain imaging studies, these coherence-building processes have been ascribed to the right hemisphe re. On the other hand, there is evidence for prefrontal brain damage causin g non-aphasic language disorders, in which text level processes are impaire d. In this study, we used an event-related, whole-head fMRI methodology to evaluate the contributions of prefrontal areas and the right hemisphere to coherence building. We scanned 12 participants while they read 120 sentence pairs and judged their coherence. Four conditions were used, resulting fro m crossing coherence and cohesion (i.e. the presence of a lexical connectio n). A behavioral pretest confirmed that cohesion aided establishing coheren ce, whereas it hindered the detection of coherence breaks. In the fMRI stud y, all language conditions yielded activation in left frontolateral and tem porolateral regions, when compared to a physical control task. The differen ces due to coherence of the sentence pairs were most evident in larger acti vation for coherent as compared to incoherent sentence pairs in the left fr ontomedian wall, but also in posterior cingulate and precuneal regions. Fin ally, a left inferior prefrontal area was sensitive to the difficulty of th e task, and in particular to the increase in processing costs when cohesion falsely indicated coherence. These results could not provide evidence for a special involvement of the right hemisphere during inferencing. Rather, t hey suggest that the left frontomedian cortex plays an important role in co herence building. (C) 2001 Elsevier Science B.V. All rights reserved.