Characterizing hemodynamic responses across species in the awake state

Motivation: Although physiological differences are more pronounced during wakefulness, interspecies similarities or differences in cerebral hemodynamic responses in the awake state have not been elucidated. Goal(s): To identify interspecies similarities or differences by analyzing hemodynamic response functions (HRFs) of awake mice, marmosets, and humans. Approach: The fMRI datasets of the three species were analyzed using the general linear model. Temporal characteristics of the HRFs (onset, time to peak [TTP], full-width at half maximum [FWHM]) were calculated and statistically compared across species. Results: While HRF shapes were similar across species, differences in TTP and FWHM were found, indicating species-specific temporal characteristics of hemodynamic responses. Impact: Our findings reveal species-specific hemodynamic differences in the awake state, enhancing translational research between awake animal models and human neuroimaging.