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Updated: Jun 9, 2026
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Interaction between Phonological and Semantic Processes in Visual Word Recognition using Electrophysiology
Published on: June 29, 2021
Phonological decisions require both the left and right supramarginal gyri
Gesa Hartwigsen1, Annette Baumgaertner, Cathy J Price
1Department of Neurology, Christian-Albrechts-University Kiel, 24105 Kiel, Germany. Gesa.Hartwigsen@gmx.de
Summary
The right supramarginal gyrus (SMG) is crucial for phonological word decisions, regardless of input modality. This study reveals the right SMG
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Psycholinguistics
Background:
- Functional imaging shows bilateral supramarginal gyrus (SMG) activation during phonological decisions.
- Lesion studies often link phonological deficits primarily to left hemisphere damage.
Purpose of the Study:
- To investigate the role of the right supramarginal gyrus (SMG) in modality-independent phonological processing using transcranial magnetic stimulation (TMS).
- To determine the task-specificity and laterality of the SMG's contribution to phonological decisions.
Main Methods:
- A dual-site transcranial magnetic stimulation (TMS) approach was employed to disrupt activity in the left, right, or bilateral supramarginal gyri (SMG) and angular gyri.
- Participants performed phonological, semantic, and perceptual decision tasks while receiving real or sham TMS.
- Task accuracy and reaction times were analyzed to assess the impact of TMS.
Main Results:
- Disrupting the left, right, or bilateral SMG selectively impaired phonological decision-making accuracy and speed compared to semantic and perceptual tasks.
- TMS over the angular gyri did not affect phonological decisions.
- The disruptive effect on phonological decisions was equivalent for unilateral TMS over the right or left SMG.
Conclusions:
- The right supramarginal gyrus (SMG) plays a significant role in phonological processing, independent of sensory modality.
- Evidence suggests that the left and right SMG do not compensate for each other during TMS-induced disruption.
- Further research on patients with right SMG damage is warranted to understand phonological deficits.
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