Revisiting the role of Broca's area in sentence processing: Syntactic integration versus syntactic working memory

• Published in: Human brain mapping Vol. 24; no. 2; pp. 79 - 91
• Main Authors: Fiebach, C.J., Schlesewsky, M., Lohmann, G., von Cramon, D.Y., Friederici, A.D.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-02-2005; Wiley-Liss
• Subjects: Adult; Biological and medical sciences; Brain Mapping; Broca's area; Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges; Cerebrovascular Circulation - physiology; Female; Frontal Lobe - anatomy & histology; Frontal Lobe - physiology; Functional Laterality - physiology; functional magnetic resonance imaging (fMRI); Fundamental and applied biological sciences. Psychology; grammar; Human; Humans; Investigative techniques, diagnostic techniques (general aspects); Language; Language Tests; Learning. Memory; Magnetic Resonance Imaging; Male; Medical sciences; Memory; Memory, Short-Term - physiology; Nerve Net - anatomy & histology; Nervous system; Photic Stimulation; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Reading; sentence comprehension; Speech Perception - physiology; syntax; Temporal Lobe - physiology; Vertebrates: nervous system and sense organs; working memory; Integration; Nervous system diseases; Broca's area; Radiodiagnosis; functional magnetic resonance imaging (fMRI); Grammar; Comprehension; Nuclear magnetic resonance imaging; Area Broca; Language; sentence comprehension; syntax; Working memory; Comparative study; Functional imaging
• ISSN: 1065-9471; 1097-0193
• DOI: 10.1002/hbm.20070

Most previous neuroimaging studies of sentence processing have associated Broca's area with syntactic processing; however, the exact nature of the processes subserved by this brain region is yet not well understood. Although some authors suggest that Brodmann area (BA) 44 of the left inferior frontal gyrus (i.e., Broca's area) is relevant for syntactic integration processes, others claim that it is associated with working memory mechanisms relevant for language processing. To dissociate these two possible functions, the present study investigated hemodynamic responses elicited while participants processed German indirect wh‐questions. Activation increases were observed in left BA 44 together with superior temporal areas and right hemispheric homologues for sentences with noncanonical word order, in which a verb argument was dislocated from its canonical position over a relatively long distance. In these sentences, syntactic working memory load was assumed to be greatest. In contrast, no activation increase was elicited by object–initial as opposed to subject–initial sentences that did not differ with respect to working memory costs but with respect to syntactic integration costs. These data strongly suggest that Broca's area plays a critical role in syntactic working memory during online sentence comprehension. Hum. Brain Mapping 24:79–91, 2005. © 2004 Wiley‐Liss, Inc.