Publication Date
12-15-2024
Journal
Human Brain Mapping
DOI
10.1002/hbm.70100
PMID
39692126
PMCID
PMC11653092
PubMedCentral® Posted Date
12-18-2024
PubMedCentral® Full Text Version
Post-print
Published Open-Access
yes
Keywords
Humans, Adult, Middle Aged, Aging, Male, Aged, Gray Matter, Cerebral Cortex, Female, Young Adult, Magnetic Resonance Imaging, Hemodynamics, Neurovascular Coupling, Cerebrovascular Circulation, Brain Mapping, BOLD fMRI, healthy aging, hemodynamic response function, whole‐brain analysis
Abstract
In functional magnetic resonance imaging, the hemodynamic response function (HRF) is a stereotypical response to local changes in cerebral hemodynamics and oxygen metabolism due to briefly (< 4 s) evoked neural activity. Accordingly, the HRF is often used as an impulse response with the assumption of linearity in data analysis. In cognitive aging studies, it has been very common to interpret differences in brain activation as age-related changes in neural activity. Contrary to this assumption, however, evidence has accrued that normal aging may also significantly affect the vasculature, thereby affecting cerebral hemodynamics and metabolism, confounding interpretation of fMRI cognitive aging studies. In this study, use was made of a multisensory task to evoke the HRF in ~87% of cerebral cortex in cognitively intact adults with ages ranging from 22 to 75 years. This widespread activation enabled us to investigate age trends in the spatial distributions of HRF characteristics within the majority of cortical gray matter, which we termed as global age trends. The task evoked both positive and negative HRFs, which were characterized using model-free parameters in native-space coordinates. We found significant global age trends in the distributions of HRF parameters in terms of both amplitudes (e.g., peak amplitude and contrast-to-noise ratio) and temporal dynamics (e.g., full-width-at-half-maximum). Our findings offer insight into how age-dependent changes affect neurovascular coupling and show promise for use of HRF parameters as non-invasive indicators for age-related pathology.
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