PT  - JOURNAL ARTICLE
AU  - Baracchini, Giulia
AU  - Zhou, Yigu
AU  - Castanheira, Jason da Silva
AU  - Hansen, Justine Y.
AU  - Rieck, Jenny
AU  - Turner, Gary R.
AU  - Grady, Cheryl L.
AU  - Misic, Bratislav
AU  - Nomi, Jason
AU  - Uddin, Lucina Q.
AU  - Spreng, R. Nathan
TI  - The biological role of local and global fMRI BOLD signal variability in human brain organization
AID  - 10.1101/2023.10.22.563476
DP  - 2023 Jan 01
TA  - bioRxiv
PG  - 2023.10.22.563476
4099  - http://biorxiv.org/content/early/2023/10/23/2023.10.22.563476.short
4100  - http://biorxiv.org/content/early/2023/10/23/2023.10.22.563476.full
AB  - Variability drives the organization and behavior of complex systems, including the human brain. Understanding the variability of brain signals is thus necessary to broaden our window into brain function and behavior. Few empirical investigations of macroscale brain signal variability have yet been undertaken, given the difficulty in separating biological sources of variance from artefactual noise. Here, we characterize the temporal variability of the most predominant macroscale brain signal, the fMRI BOLD signal, and systematically investigate its statistical, topographical and neurobiological properties. We contrast fMRI acquisition protocols, and integrate across histology, microstructure, transcriptomics, neurotransmitter receptor and metabolic data, fMRI static connectivity, and empirical and simulated magnetoencephalography data. We show that BOLD signal variability represents a spatially heterogeneous, central property of multi-scale multi-modal brain organization, distinct from noise. Our work establishes the biological relevance of BOLD signal variability and provides a lens on brain stochasticity across spatial and temporal scales.Competing Interest StatementThe authors have declared no competing interest.