Name
Abstract | ||
|---|---|---|
Analysis of task-evoked fMRI data ignores low frequency fluctuations (LFF) of the resting-state the BOLD signal, yet LFF of the spontaneous BOLD signal is crucial for analysis of resting-state connectivity maps. We characterized the LFF of resting-state BOLD signal at 11.7T in α-chloralose and domitor anesthetized rat brain and modeled the spontaneous signal as a scale-free (i.e., fractal) distribution of amplitude power (|A|2) across a frequency range (f) compatible with an |A(f)|2∝1/fβ model where β is the scaling exponent (or spectral index). We compared β values from somatosensory forelimb area (S1FL), cingulate cortex (CG), and caudate putamen (CPu). With α-chloralose, S1FL and CG β values dropped from ~0.7 at in vivo to ~0.1 at post mortem (p<0.0002), whereas CPu β values dropped from ~0.3 at in vivo to ~0.1 at post mortem (p<0.002). With domitor, cortical (S1FL, CG) β values were slightly higher than with α-chloralose, while subcortical (CPu) β values were similar with α-chloralose. Although cortical and subcortical β values with both anesthetics were significantly different in vivo (p<0.002), at post mortem β values in these regions were not significantly different and approached zero (i.e., range of −0.1 to 0.2). Since a water phantom devoid of susceptibility gradients had a β value of zero (i.e., random), we conclude that deoxyhemoglobin present in voxels post-sacrifice still impacts tissue water diffusion. These results suggest that in the anesthetized rat brain the LFF of BOLD signal at 11.7T follow a general 1/fβ model of fractality where β is a variable responding to physiology. We describe typical experimental pitfalls which may elude detection of fractality in the resting-state BOLD signal. |
Year | DOI | Venue |
|---|---|---|
2011 | 10.1016/j.neuroimage.2011.06.082 | NeuroImage |
Keywords | Field | DocType |
Resting-state connectivity,BOLD signal,Fractality,Self-similarity,Scale-free correlation,Frequency domain analysis,Non-linear dynamics | Frequency domain,Fractal analysis,Cingulate cortex,Putamen,Neuroscience,Fractal,Psychology,Somatosensory system,Forelimb,Amplitude | Journal |
Volume | Issue | ISSN |
58 | 4 | 1053-8119 |
Citations | PageRank | References |
3 | 0.39 | 8 |
Authors | ||
4 | ||
Name | Order | Citations | PageRank |
|---|---|---|---|
| Peter Herman | 1 | 9 | 2.94 |
| Basavaraju G. Sanganahalli | 2 | 13 | 3.66 |
| Fahmeed Hyder | 3 | 42 | 9.53 |
| Andras Eke | 4 | 3 | 0.39 |