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Abstract:
This study was designed to investigate the neuroanatomical
regions associated with processing morphologically simple and
complex words embedded in short phrases. The complex words were
composed of a stem (faith) and a derivational affix (-ful). Since
derivational affixes determine the grammatical category of complex
words, we hypothesized that there may be different computational
processes involved in accessing the grammatical category of complex
and simple words that map onto different neuroanatomical
activations. We used an event-related fMRI paradigm to track the
relative hemodynamic responses in regions activated during the
task. Participants judged the grammaticality of three-word phrases
(he is faithful) with either complex or simple target words. No
regions demonstrated an exclusive response to complex words,
suggesting a lack of dedicated processing for morphological
complexity. We found regions associated with effects of
grammaticality (anterior and posterior cingulate as well as left
angular gyrus) and with graded effects of morphological complexity
(left DLPFC and Broca's area). In addition, the left caudate and
thalamus showed differential responses to grammaticality across
morphological complexity. Our findings indicate that morphological
complexity influences activation in language related brain regions
and may facilitate grammaticality judgements. These results
demonstrate that there may be important interactions between
word-level morphology and phrase-level grammaticality.
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