How Brain Works in Resting State?

Resting State Brain is Fractal

How does the brain work when you sleep? A key to answer this question is to figure out that the resting state brain functions are 'fractal'. We have developed parsimonious fractal-based methodologies to reveal the functional mechanism of the resting state brain through functional magnetic resonance imaging (fMRI).

A blood oxygen level dependent (BOLD) MRI signals taken at rest tends to exhibit 1/f power-law scaling or temporally long-range dependence called the 'fractality'. In the pioneering project of Leibniz Institute for Neurobiology, we have proposed a computational model of resting state brain activities which describes not only the physical mechanism of fractality in BOLD signals but also the theoretical relationship between fractality and functional connectivity. We finally have suggested a novel method based on wavelets, which allows us to estimate functional connectivity of endogenous neuronal activities hidden beyond the fractality of BOLD signals, and suggested the 'nonfractal connectivity' as a new concept for quantifying brain functional network (IJCNN 2012).

Fractal-based Brain Imaging: Applications

The fractal-based analysis of resting state fMRI had been applied not only to the effects of electric stimulation on resting state functional connectivity in the rat brain, but also to studying resting state brain functions in patients with major depression disorders (MDD) (Dissertation 2013). We were recently involved in an international joint research program for neuroimaging study on autism by cooperating with University of Cyprus (Cyprus), University of Cambridge (UK), and the Hospital for Sick Children (Canada). Using the fractal approach to resting state fMRI, the study showed that a difference in brain functions pertinent to social cognition may be present between male and female with autism (OHBM 2019). We are continuously pursuing to develop new clinical applications of the fractal-based data analysis for a variety of brain diseases including brain tumors, dementia, autism, and so forth.


Software

  • nonfractal: Nonfractal Connectivity Estimator

  • long-memory: The MATLAB Toolbox for the Analysis of Long Memory Processes

Publications

Presentations