Reducing vascular variability of fMRI data across aging populations using a breathholding task

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Vascular Physiology

Background:

• Blood oxygen level-dependent (BOLD) signal variability in functional MRI (fMRI) complicates interpretation.
• Differences in neural activity or vasculature contribute to BOLD signal changes.
• Aging impacts brain function and vascular reactivity, affecting fMRI results.

Purpose of the Study:

• To compare BOLD responses to neural activity versus vascular challenge.
• To test a method for dissociating neural and vascular influences on fMRI signals.
• To investigate age-related differences in BOLD responses and vascular reactivity.

Main Methods:

• fMRI scans were conducted on younger and older adults performing a visuomotor saccade task (neural) and a breath-holding task (vascular challenge).
• BOLD signal magnitude, time-to-peak, and phase were analyzed for both tasks.
• A ratio of saccade task magnitude to hypercapnia task magnitude was used to isolate neural contributions.

Main Results:

• Aging led to decreased BOLD signal magnitude in FEF, SEF, and V1, and delayed time-to-peak in V1 during the saccade task.
• Signal magnitudes from both tasks showed significant linear regressions across subjects and populations.
• The age-related decrease in V1 signal magnitude persisted after normalization, indicating a neural origin.

Conclusions:

• The proposed method can differentiate neural and vascular contributions to BOLD signals.
• Aging affects neural BOLD responses, independent of vascular reactivity changes.
• This approach may enable identification and correction of vascular reactivity confounds in fMRI studies across populations.