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Automatic and controlled semantic retrieval: TMS reveals distinct contributions of posterior middle temporal gyrus and angular gyrus
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Abstract:
Semantic retrieval involves both (1) automatic spreading activation between highly related concepts and (2) executive control processes that tailor this activation to suit the current context or goals. Two structures in left temporoparietal cortex, angular gyrus (AG) and posterior middle temporal gyrus (pMTG), are thought to be crucial to semantic retrieval and are often recruited together during semantic tasks; however, they show strikingly different patterns of functional connectivity at rest (coupling with the "default mode network" and "frontoparietal control system," respectively). Here, transcranial magnetic stimulation (TMS) was used to establish a causal yet dissociable role for these sites in semantic cognition in human volunteers. TMS to AG disrupted thematic judgments particularly when the link between probe and target was strong (e.g., a picture of an Alsatian with a bone), and impaired the identification of objects at a specific but not a superordinate level (for the verbal label "Alsatian" not "animal"). In contrast, TMS to pMTG disrupted thematic judgments for weak but not strong associations (e.g., a picture of an Alsatian with razor wire), and impaired identity matching for both superordinate and specific-level labels. Thus, stimulation to AG interfered with the automatic retrieval of specific concepts from the semantic store while stimulation of pMTG impaired semantic cognition when there was a requirement to flexibly shape conceptual activation in line with the task requirements. These results demonstrate that AG and pMTG make a dissociable contribution to automatic and controlled aspects of semantic retrieval.
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Keyword:
Cognition; Connectivity; Fmri Evidence; Human Brain; Knowledge; Parietal Cortex; Prefrontal Cortex; Representation; System; Word Comprehension
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URL: https://espace.library.uq.edu.au/view/UQ:5694827
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Charting the functional relevance of Broca’s area for visual word recognition and picture naming in Dutch using fMRI-guided TMS
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The neural basis of the right visual field advantage in reading: an MEG analysis using virtual electrodes
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In: Brain and Language, Vol. 118, no. 3 (Sep 2011), pp. 53-71 (2011)
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The first 250 ms in visual word recognition: who is talking to whom
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The neural basis of the right visual field advantage in reading: an MEG analysis using virtual electrodes
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During visual word recognition phonology is accessed by 100ms and may be mediated by a speech production code: Evidence from MEG
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During visual word recognition, phonology is accessed within 100 ms and may be mediated by a speech production code: evidence from magnetoencephalography
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Activation of the left inferior frontal gyrus in the first 200 ms of reading:evidence from magnetoencephalography (MEG)
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Visual word recognition insights from MEG and implications for developmental dyslexia
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Phase Coupling in a Cerebro-Cerebellar Network at 8-13 Hz during Reading
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Phase Coupling in a Cerebro-Cerebellar Network at 8-13 Hz during Reading
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