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Abstract:
Event-related functional magnetic resonance imaging was used
to identify brain regions involved in syntactic and semantic
processing. Sixteen right-handed adult males read well-formed
sentences randomly intermixed with sentences containing anomalies
either of syntactic phrase structure (e.g., *"I cut Max's with
apple a knife") or of conceptual semantics (e.g., *"I sailed Todd's
hotel to China"). In a previous event-related potential (ERP) study
using the same sentences and experimental paradigm, syntactic
violations yielded an early left anterior negativity (LAN) and
later positivity (P600), whereas semantic anomalies yielded an
N400. In the present fMRI study, reading anomalous sentences as
compared to well-formed sentences similarly yielded distinct
patterns of BOLD hemodynamic activity for the two violation types.
Syntactic violations elicited significantly greater activation than
semantic violations primarily in superior frontal cortex, in or
near the supplementary motor area. Semantically anomalous sentences
elicited greater activation than syntactic violations primarily in
temporal/temporo-parietal regions (left hippocampal and
parahippocampal gyri, right middle temporal gyrus, bilateral
angular gyri), as well as the left inferior frontal sulcus. These
results demonstrate that syntactic and semantic processing result
in non-identical patterns of activation, including greater frontal
engagement during syntactic processing and larger increases in
temporal and temporo-parietal regions during semantic
analyses.
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