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Attention strongly increases oxygen metabolic response to stimulus in primary visual cortex
Farshad Moradi1, Giedrius T Buračas, Richard B Buxton
1Center for Functional MRI and Department of Radiology, University of California, San Diego, CA 92103-8756, USA. fmoradi@ucsd.edu
Neuroimage
|August 16, 2011
Summary
Top-down attention significantly impacts brain metabolism. New research reveals that blood flow changes in the primary visual cortex (V1) are greater than BOLD signals, indicating substantial metabolic modulation during attention.
Area of Science:
- Neuroscience
- Cognitive Science
- Neuroimaging
Background:
- Top-down attention modulates neural processing.
- The precise effect of attention on primary visual cortex (V1) metabolic activity remains unclear.
- Combined blood flow and oxygenation measurements are crucial for studying oxidative metabolism.
Purpose of the Study:
- To investigate the modulatory effects of attention on metabolic activity in human V1.
- To differentiate between blood flow and blood oxygenation level dependent (BOLD) responses under attentional control.
Main Methods:
- Utilized functional magnetic resonance imaging (fMRI) to measure human V1 responses.
- Employed combined blood flow and oxygenation measurements.
- Presented a peripheral low-contrast visual stimulus to participants.
Main Results:
- Found a larger fractional modulation of blood flow compared to the BOLD response in V1 with attention.
- Indicated a significantly greater modulation of oxygen metabolism than previously understood.
- Highlighted that different neural activity aspects drive flow and metabolic changes differentially.
Conclusions:
- V1 blood flow is primarily driven by initial sensory activity, especially in unattended states.
- V1 oxygen metabolism is strongly influenced by overall neural activity, which is modulated by attentional top-down signals.
- Attention exerts a more substantial influence on V1 metabolic activity than suggested by BOLD signals alone.
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