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Updated: Apr 3, 2026
Author Spotlight: Insights into Visual Cortex Research Through Wide-View fMRI Mapping
Published on: December 8, 2023
Quantitative assessment of visual cortex function with fMRI at 7 Tesla-test-retest variability.
Aini Ismafairus Abd Hamid1, Oliver Speck2, Michael B Hoffmann3
1Department of Biomedical Magnetic Resonance, Institute for Experimental Physics, Otto-von-Guericke University Magdeburg Magdeburg, Germany ; Department of Neurosciences, School of Medical Sciences Health Campus, Universiti Sains Malaysia Kubang Kerian, Malaysia.
Longitudinal functional Magnetic Resonance Imaging (fMRI) studies reveal changes in brain activity over time. Cognitive factors, not head motion, likely explain these variations in brain mapping experiments.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Functional Magnetic Resonance Imaging (fMRI) is crucial for mapping brain activity.
- Longitudinal studies require understanding variations in fMRI signals across sessions.
- Subject experience and cognitive factors may influence fMRI results over time.
Purpose of the Study:
- To assess variations in activated cortical surface area, amplitude, and coherence in fMRI retinotopic mapping across multiple sessions.
- To investigate the underlying causes of observed changes in fMRI signals, differentiating between head motion and cognitive effects.
- To determine the sensitivity of fMRI measures for detecting inter-session changes and provide methodological guidance for longitudinal studies.
Main Methods:
- Utilized 7 Tesla fMRI for high-resolution retinotopic mapping in seven healthy subjects.
- Acquired data across three separate sessions with varying time intervals (approx. 50 and 170 days).
- Analyzed changes in activated cortical surface area, response amplitude, and coherence between sessions.
Main Results:
- Observed significant reductions in activated cortical surface area (Sessions 1-2), amplitude (Sessions 1-3), and coherence (Sessions 1-3).
- Phase correlations for retinotopic maps (eccentricity, polar angle) remained highly correlated across sessions, indicating map stability.
- Head motion was not identified as the primary driver of observed signal changes; cognitive effects are suggested as the cause.
- Sensitivity for detecting inter-session changes was estimated at 1.5% for cortical surface area, 6% for amplitude, and 5% for coherence (5% significance level).
Conclusions:
- Cognitive effects, rather than head motion, appear to influence fMRI signal variations in longitudinal studies.
- Retinotopic maps demonstrate stability across sessions, but quantitative measures of activation change.
- Longitudinal fMRI studies must carefully evaluate inter-session activation to ensure data validity and consider the impact of subject experience.
