Functional magnetic resonance imaging (fMRI) is sensitive to hemodynamic fluctuations in the human brain. Functional connectivity maps created by calculating the correlation between fluctuations from different brain areas show high correlation in areas that are known to be strongly connected. The correlation is presumed to be related to coordinated neural activity. This technique is increasingly used to probe networks of brain activity in both normal subjects and patients with neurological disorders. However, the physiological basis of the hemodynamic fluctuations and the connection to underlying neural activity are not well understood. The ultimate goal of our research is to definitively establish the relationship between functional connectivity measured with MRI and neural activity. It is difficult to probe the relationship between the two in humans, and few functional connectivity studies have been performed in animals to date. This study proposes to elucidate the relationship between correlated MRI signal fluctuations and neural activity by combining microelectrode recording and imaging in the rodent. Recording will occur between images, so that electrical coherence and MRI correlations can be directly compared.
The specific aim of this proposal is: Determine the relationship between functional connectivity and neural activity by interleaving microelectrode recordings and image acquisition in a rodent model.: Functional connectivity will be measured in rats using perfusion, blood oxygenation, and blood-volume weighted MRI to identify which vascular property is the predominant source of signal fluctuations. Hypercapnia will be induced to determine whether it suppresses connectivity as in human studies. Respiratory and cardiac cycles will be recorded to determine their contributions to correlation. Recording of local field potentials and acquisition of MRI images will be interleaved and acquired as anesthesia level is varied to alter neural activity, and coherence in recordings from each pair of electrodes will be calculated and compared to correlation observed with MRI. The goal of this project is to determine the relationship between functional connectivity and neural activity. This is the first step toward our long-term goal of establishing functional connectivity mapping as a noninvasive tool for the diagnosis and evaluation of clinical neurological disorders.

Public Health Relevance

The goal of this project is to determine the relationship between functional connectivity measured with MRI in the rodent and the underlying neural activity. This is the first step toward our long-term goal of establishing functional connectivity mapping as a noninvasive tool for the diagnosis and evaluation of clinical neurological disorders. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21NS057718-01A2
Application #
7589522
Study Section
Cognitive Neuroscience Study Section (COG)
Program Officer
Chen, Daofen
Project Start
2008-09-01
Project End
2010-08-31
Budget Start
2008-09-01
Budget End
2009-08-31
Support Year
1
Fiscal Year
2008
Total Cost
$200,514
Indirect Cost
Name
Emory University
Department
Biomedical Engineering
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
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
Thompson, Garth John; Pan, Wen-Ju; Keilholz, Shella Dawn (2015) Different dynamic resting state fMRI patterns are linked to different frequencies of neural activity. J Neurophysiol 114:114-24
Thompson, Garth John; Pan, Wen-Ju; Magnuson, Matthew Evan et al. (2014) Quasi-periodic patterns (QPP): large-scale dynamics in resting state fMRI that correlate with local infraslow electrical activity. Neuroimage 84:1018-31
Magnuson, Matthew E; Thompson, Garth J; Pan, Wen-Ju et al. (2014) Effects of severing the corpus callosum on electrical and BOLD functional connectivity and spontaneous dynamic activity in the rat brain. Brain Connect 4:15-29
Pan, Wen-Ju; Thompson, Garth John; Magnuson, Matthew Evan et al. (2013) Infraslow LFP correlates to resting-state fMRI BOLD signals. Neuroimage 74:288-97
Thompson, Garth John; Merritt, Michael Donelyn; Pan, Wen-Ju et al. (2013) Neural correlates of time-varying functional connectivity in the rat. Neuroimage 83:826-36
Keilholz, Shella D; Magnuson, Matthew E; Pan, Wen-Ju et al. (2013) Dynamic properties of functional connectivity in the rodent. Brain Connect 3:31-40
Majeed, Waqas; Magnuson, Matthew; Hasenkamp, Wendy et al. (2011) Spatiotemporal dynamics of low frequency BOLD fluctuations in rats and humans. Neuroimage 54:1140-50
Pan, Wen-Ju; Thompson, Garth; Magnuson, Matthew et al. (2011) Broadband local field potentials correlate with spontaneous fluctuations in functional magnetic resonance imaging signals in the rat somatosensory cortex under isoflurane anesthesia. Brain Connect 1:119-31

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