Abstract
Activity of cortical local neuronal populations fluctuates continuously, and a large proportion of these fluctuations are shared across populations of neurons. Here we seek organizational rules that link these two phenomena. Using neuronal activity, as identified by functional MRI (fMRI) and for a given voxel or brain region, we derive a single measure of full bandwidth brain-oxygenation-level-dependent (BOLD) fluctuations by calculating the slope, α, for the log-linear power spectrum. For the same voxel or region, we also measure the temporal coherence of its fluctuations to other voxels or regions, based on exceeding a given threshold, Θ, for zero lag correlation, establishing functional connectivity between pairs of neuronal populations. From resting state fMRI, we calculated whole-brain group-averaged maps for α and for functional connectivity. Both maps showed similar spatial organization, with a correlation coefficient of 0.75 between the two parameters across all brain voxels, as well as variability with hodology. A computational model replicated the main results, suggesting that synaptic low-pass filtering can account for these interrelationships. We also investigated the relationship between α and structural connectivity, as determined by diffusion tensor imaging-based tractography. We observe that the correlation between α and connectivity depends on attentional state; specifically, α correlated more highly to structural connectivity during rest than while attending to a task. Overall, these results provide global rules for the dynamics between frequency characteristics of local brain activity and the architecture of underlying brain networks.
Original language | English (US) |
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Pages (from-to) | 144-155 |
Number of pages | 12 |
Journal | Neuroimage |
Volume | 73 |
DOIs | |
State | Published - Jun 2013 |
Funding
We thank all the members of the Apkarian lab for their contributions to this study. We also thank Michael Breakspear for generously sharing Matlab code for wavelet resampling. The study was funded by the National Institute of Neurological Disorders and Stroke ( NS35115 ).
Keywords
- BOLD fMRI
- Connectivity
- DTI tractography
- Hodology
- Power spectrum
ASJC Scopus subject areas
- Neurology
- Cognitive Neuroscience