scholarly journals Nonlinear manifold learning in functional magnetic resonance imaging uncovers a low‐dimensional space of brain dynamics

2021 ◽  
Author(s):  
Siyuan Gao ◽  
Gal Mishne ◽  
Dustin Scheinost
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Manifold Learning ◽  
Dimensional Space ◽  
Brain Dynamics ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Low Dimensional

scholarly journals Neural Dynamics during Resting State: A Functional Magnetic Resonance Imaging Exploration with Reduction and Visualization

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Wei Li ◽  
Miao Wang ◽  
Wen Wen ◽  
Yue Huang ◽  
Xi Chen ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Resting State ◽  
Dimensional Space ◽  
Low Frequency ◽  
Two Dimensional ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Neural Signals

The brain is a complex high-order system. Body movements or mental activities are both dependent on the transmission of information among billions of neurons. However, potential patterns are hardly discoverable due to the high dimensionality in neural signals. Previous studies have identified rotary trajectories in rhythm and nonrhythm movements when projecting the neural electrical signals into a two-dimensional space. However, it is unclear how well this analogy holds at the resting state. Given the low-frequency fluctuations noted during spontaneous neural activities using functional magnetic resonance imaging (fMRI), it is natural to hypothesize that the neural response at resting state also shows a periodic trajectory. In this study, we explored the potential patterns in resting state fMRI data at four frequency bands (slow 2–slow 5) on two cohorts, one of which consisted of young and elderly adults and the other of patients with Alzheimer’s disease and normal controls (NC). The jPCA algorithm was applied to reduce the high-dimensional BOLD signal into a two-dimensional space for visualization of the trajectory. The results indicated that the “resting state” is a basic state showing an inherent dynamic pattern with a low frequency and long period during normal aging, with changes appearing in the rotary period at the slow 4 frequency band (0.027–0.073 Hz) during the pathological process of Alzheimer’s disease (AD). These findings expand the original understanding that neural signals can rotate themselves and that motor executive signals consist of neural signals. Meanwhile, the rotary period at band slow 4 may be a physiological marker for AD, and studies of this frequency band may be useful for understanding the potential pathophysiology of AD and ultimately facilitate characterization and auxiliary diagnosis of AD.

Functional Magnetic Resonance Imaging Measures of Blood Flow Patterns in the Human Auditory Cortex in Response to Sound

1998 ◽  
Vol 41 (3) ◽  
pp. 538-548 ◽  
Author(s):  
Sean C. Huckins ◽  
Christopher W. Turner ◽  
Karen A. Doherty ◽  
Michael M. Fonte ◽  
Nikolaus M. Szeverenyi
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Speech Stimuli ◽  
Complex Stimuli ◽  
Scanning Session ◽  
Auditory Research

Functional Magnetic Resonance Imaging (fMRI) holds exciting potential as a research and clinical tool for exploring the human auditory system. This noninvasive technique allows the measurement of discrete changes in cerebral cortical blood flow in response to sensory stimuli, allowing determination of precise neuroanatomical locations of the underlying brain parenchymal activity. Application of fMRI in auditory research, however, has been limited. One problem is that fMRI utilizing echo-planar imaging technology (EPI) generates intense noise that could potentially affect the results of auditory experiments. Also, issues relating to the reliability of fMRI for listeners with normal hearing need to be resolved before this technique can be used to study listeners with hearing loss. This preliminary study examines the feasibility of using fMRI in auditory research by performing a simple set of experiments to test the reliability of scanning parameters that use a high resolution and high signal-to-noise ratio unlike that presently reported in the literature. We used consonant-vowel (CV) speech stimuli to investigate whether or not we could observe reproducible and consistent changes in cortical blood flow in listeners during a single scanning session, across more than one scanning session, and in more than one listener. In addition, we wanted to determine if there were differences between CV speech and nonspeech complex stimuli across listeners. Our study shows reproducibility within and across listeners for CV speech stimuli. Results were reproducible for CV speech stimuli within fMRI scanning sessions for 5 out of 9 listeners and were reproducible for 6 out of 8 listeners across fMRI scanning sessions. Results of nonspeech complex stimuli across listeners showed activity in 4 out of 9 individuals tested.

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