Resting state functional magnetic resonance imaging (rs-fMRI) contains a wealth of information about the large-scale structure of neural activity in the brain, an area that has been relatively unexplored. Rs-fMRI has provided some insight into the macroscopic organization of brain activity by identifying functional networks that are reproducible across subjects. The functional networks are often interpreted as if they represent time- varying interactions between areas of the type that would be expected to arise from cognitive processes, but the same network structure can be found in conditions where cognition is suppressed or absent (sleep, coma, and anesthesia). This persistent network structure is one of the lingering puzzles in rs-fMRI. Our previous work has shown that large-scale spatiotemporal quasi-periodic patterns (QPPs) of electrical activity can be isolated from the BOLD signal, allowing us to separate slow, semi-periodic modulations from the more localized aperiodic activity that is expected to arise from cognition and information processing. This led us to hypothesize that the QPPs account for a persistent background pattern of neuromodulation, over which time-varying contributions from cognition and information processing are superimposed. Our preliminary data indicates that QPPs arise from a different type of brain activity than the neural activity linked to information processing and cognition but still account for a substantial portion of the functional connectivity in the brain.
In Aim 1 , we extend our previous work to investigate the neurophysiological sources that play a role in QPP generation using multimodal imaging in the rat. Our working model is that the QPPs arise from localized input from subcortical nuclei that then propagates across the cortex through the coordinated actions of neurons and astrocytes. In humans, the QPPs are most dominant in the default mode network (DMN), a critical structure implicated in numerous functions and altered in many disorders. Our preliminary data shows that QPPs account for a substantial portion of the connectivity in the DMN.
In Aim 2, we will compare functional network metrics throughout the brain before and after the QPPs are removed by regression to determine how the presence of the infraslow modulation impacts standard analysis.
Our final aim directly examines the hypothesis that QPPs account for background activity over which time- varying activity more relevant to cognition is superimposed. We will calculate the relative contribution of QPPs to the BOLD signal as a function of anesthetic depth in rats, where we expect their contribution to increase as anesthetic depth increases, and during tasks with varying difficulty in humans, where we expect their relative contribution to decrease as a function of increasing cognitive demand. Taken together, the work in this proposal will change the way we interpret rs-fMRI by allowing separate examination of two distinct components of brain activity that may both be of clinical interest.

Public Health Relevance

We have developed a new method of analysis that isolates different components of the functional MRI signal that coexist on different spatial and temporal scales. Our working hypothesis is that one component represents aperiodic activity linked to cognition and information processing; that the other component describes a quasiperiodic pattern of neuromodulatory input; and that separation of the two components may improve sensitivity to changes of interest in brain disorders. This proposal examines the sources of the quasiperiodic patterns, their role in functional connectivity, and whether they account for the persistence of functional networks across varying levels of cognition.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS078095-07
Application #
9700230
Study Section
Neuroscience and Ophthalmic Imaging Technologies Study Section (NOIT)
Program Officer
Babcock, Debra J
Project Start
2012-09-20
Project End
2023-05-31
Budget Start
2019-06-01
Budget End
2020-05-31
Support Year
7
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Emory University
Department
Biomedical Engineering
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Pan, Wen-Ju; Lee, Seung Yup; Billings, Jacob et al. (2018) Detection of neural light-scattering activity in vivo: optical transmittance studies in the rat brain. Neuroimage 179:207-214
Belloy, Michaƫl E; Shah, Disha; Abbas, Anzar et al. (2018) Quasi-Periodic Patterns of Neural Activity improve Classification of Alzheimer's Disease in Mice. Sci Rep 8:10024
Yousefi, Behnaz; Shin, Jaemin; Schumacher, Eric H et al. (2018) Quasi-periodic patterns of intrinsic brain activity in individuals and their relationship to global signal. Neuroimage 167:297-308
Billings, Jacob C W; Thompson, Garth J; Pan, Wen-Ju et al. (2018) Disentangling Multispectral Functional Connectivity With Wavelets. Front Neurosci 12:812
Shakil, Sadia; Billings, Jacob C; Keilholz, Shella D et al. (2018) Parametric Dependencies of Sliding Window Correlation. IEEE Trans Biomed Eng 65:254-263
Billings, Jacob C W; Medda, Alessio; Shakil, Sadia et al. (2017) Instantaneous brain dynamics mapped to a continuous state space. Neuroimage 162:344-352
Keilholz, Shella D; Pan, Wen-Ju; Billings, Jacob et al. (2017) Noise and non-neuronal contributions to the BOLD signal: applications to and insights from animal studies. Neuroimage 154:267-281
Medda, Alessio; Hoffmann, Lukas; Magnuson, Matthew et al. (2016) Wavelet-based clustering of resting state MRI data in the rat. Magn Reson Imaging 34:35-43
Keilholz, Shella D; Billings, Jacob C W; Kai Wang et al. (2016) Multiscale network activity in resting state fMRI. Conf Proc IEEE Eng Med Biol Soc 2016:61-64
Shakil, Sadia; Lee, Chin-Hui; Keilholz, Shella Dawn (2016) Evaluation of sliding window correlation performance for characterizing dynamic functional connectivity and brain states. Neuroimage 133:111-128

Showing the most recent 10 out of 20 publications