Comparing BOLD and VASO-CBV population receptive field estimates in human visual cortex.

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Functional Magnetic Resonance Imaging (fMRI)

Background:

• Vascular Space Occupancy (VASO) fMRI measures cerebral blood volume (CBV) changes.
• VASO-CBV fMRI offers potential for higher spatial specificity than BOLD fMRI due to localized CBV response.
• Comparing VASO-CBV and BOLD fMRI is crucial for advancing cognitive neuroscience applications.

Purpose of the Study:

• To compare population receptive field (pRF) mapping estimates between BOLD and VASO-CBV fMRI.
• To investigate if VASO-CBV elicits distinct pRF properties compared to BOLD.
• To determine if reduced vascular blurring in VASO-CBV leads to narrower pRFs.

Main Methods:

• Utilized a VASO sequence with a double readout 3D EPI sequence at 7T.
• Simultaneously measured VASO-CBV and BOLD responses in the visual cortex.
• Employed conventional pRF mapping stimuli during data acquisition.

Main Results:

• Both VASO-CBV and BOLD fMRI produced comparable eccentricity and polar angle maps.
• VASO-CBV exhibited lower temporal signal-to-noise ratio (tSNR) and variance explained than BOLD.
• pRF size varied with eccentricity similarly for both methods, with comparable estimates.

Conclusions:

• The vascular component does not appear to dominate pRF size estimates in either VASO-CBV or BOLD fMRI.
• Despite theoretical advantages, VASO-CBV did not yield significantly different pRF size estimates compared to BOLD.
• Further research may be needed to optimize VASO-CBV for enhanced spatial resolution in pRF mapping.