AUTHOR=Alahäivälä Aino-Lotta I. , Thaploo Divesh , Wein Simon , Seidel Philipp , Riebel Marco , Hummel Thomas , Schwarzbach Jens Volkmar 

TITLE=Inhalation-modulated detection of olfactory BOLD responses in the human brain

JOURNAL=Frontiers in Neuroimaging

VOLUME=Volume 2 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/neuroimaging/articles/10.3389/fnimg.2023.1260893

DOI=10.3389/fnimg.2023.1260893

ISSN=2813-1193

ABSTRACT=Unlike in other sensory domains, detecting primary olfactory processes using functional magnetic resonance has been notoriously difficult with so called block designs due to substantial habituation and hemodynamic responses in olfactory areas that do not seem to follow extended box car functions convolved with a generic hemodynamic response model. Therefore, several researchers have proposed to switch to event related designs, which are known to have lower detection power than block designs. Here, we conducted a block-design experiment with 16s of continuous stimulation with an odorant alternating with 16s epochs of continuous stimulation with odorless air in 33 healthy participants and compared four statistical analyses that either relied on standard block designs (SBD1-2) with or on block designs that were modulated by the participants' individual breathing patterns (MBD1-2). We found that such modulated block designs were comparatively powerful to standard block designs despite having a substantially lower design efficiency. Using whole-brain effect size maps we observed that the right insular and medial aspects of the left piriform cortex exhibited a preference for a breathing modulated analysis-approach.