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Activation in left primary visual cortex representing parafoveal visual field during reading Japanese texts
Yoichi Shimada1, Kazumi Hirayama, Satoshi Nakadomari
1Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, 2-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan. youichi@rehab.tbgu.ac.jp
Brain Research
|July 23, 2011
Summary
Attentional modulation during Japanese text reading occurs in the left primary visual cortex (V1). This activation is fixed at approximately 4.5° eccentricity, regardless of the distance to the next Kanji word.
Area of Science:
- Neuroscience
- Cognitive Science
- Visual Perception
Background:
- Text reading involves attentional modulation in the left primary visual cortex (V1).
- In Japanese, Kanji words guide saccadic eye movements for reading.
- The precise location and adaptability of this V1 modulation remain unclear.
Purpose of the Study:
- To pinpoint the location of V1 activation during Japanese text reading.
- To investigate if this activation shifts based on the distance to the next Kanji word.
- To understand the role of parafoveal V1 in guiding saccades for reading.
Main Methods:
- Functional magnetic resonance imaging (fMRI) to map V1 activation.
- Determined V1 representation of visual field eccentricities for each participant.
- Recorded eye movements during leftward scrolling Japanese text (3° and 5° Kanji spacing).
Main Results:
- Maximum V1 activation peaked in the region representing ~4.5° eccentricity on the horizontal meridian.
- Activation patterns were consistent across both text conditions (3° and 5° spacing).
- Saccade targets aligned with Kanji word locations, but V1 modulation remained fixed.
Conclusions:
- Attentional modulation during Japanese text reading is localized to parafoveal V1 in the left hemisphere.
- This modulation is fixed at approximately 4.5° eccentricity and does not adapt to varying saccade target distances.
- V1 plays a consistent role in processing upcoming text, irrespective of inter-word spacing.
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