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Reading, hearing, and the planum temporale
Bradley R Buchsbaum1, Rosanna K Olsen, Paul F Koch
1Department of Health and Human Services, Unit on Integrative Neuroimaging, Clinical Brain Disorders Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1365, USA. brad.buchsbaum@nih.gov
Neuroimage
|January 4, 2005
Summary
Spatial smoothing in neuroimaging affects planum temporale (PT) activation during reading. Moderate smoothing (5 mm) reveals the speech area (Spt), while excessive smoothing (10 mm) obscures it, explaining past study discrepancies.
Area of Science:
- Neuroimaging
- Cognitive Neuroscience
- Speech Perception
Background:
- Neuroimaging studies show consensus on reading-related brain regions.
- The planum temporale (PT) is surprisingly absent from consistently active regions in reading tasks.
- Emerging evidence suggests the left posteromedial PT is involved in speech production and perception.
Purpose of the Study:
- Investigate the role of the PT in single-word reading and speech perception.
- Determine the influence of spatial smoothing on PT activation during reading.
- Clarify why PT involvement is often missed in neuroimaging studies of reading.
Main Methods:
- Employed a high-powered rapid event-related fMRI paradigm.
- Assessed activity in the PT during single pseudoword reading and listening.
- Varied the degree of spatial smoothing applied to functional images (5 mm vs. 10 mm).
Main Results:
- The Sylvian-parietal-temporal (Spt) speech area of the PT is optimally identified with moderate (5 mm) spatial smoothing.
- Increasing spatial smoothing to 10 mm completely eliminates PT activation.
- This suggests spatial smoothing is a critical factor in detecting PT involvement.
Conclusions:
- Moderate spatial smoothing is crucial for identifying the Spt region within the PT during reading tasks.
- Excessive smoothing can lead to the underestimation or absence of PT activation in neuroimaging.
- Findings reconcile previous discrepancies regarding PT involvement in reading and speech processing.