TE-dependent spatial and spectral specificity of functional connectivity

Changwei W Wu, Hong Gu, Qihong Zou, Hanbing Lu, Elliot A Stein, Yihong Yang

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Previous studies suggest that spontaneous fluctuations in the resting-state fMRI (RS-fMRI) signal may reflect fluctuations in transverse relaxation time (T(2)(*)) rather than spin density (S(0)). However, such S(0) and T(2)(*) features have not been well characterized. In this study, spatial and spectral characteristics of functional connectivity on sensorimotor, default-mode, dorsal attention, and primary visual systems were examined using a multiple gradient-echo sequence at 3T. In the spatial domain, we found broad, local correlations at short echo times (TE ≤ 14 ms) due to dominant S(0) contribution, whereas long-range connections mediated by T(2)(*) became explicit at TEs longer than 22 ms. In the frequency domain, compared with the flat spectrum of S(0), spectral power of the T(2)(*)-weighted signal elevated significantly with increasing TE, particularly in the frequency ranges of 0.008-0.023 Hz and 0.037-0.043 Hz. Using the S(0) spectrum as a reference, we propose two indices to measure spectral signal change (SSC) and spectral contrast-to-noise ratio (SCNR), respectively, for quantifying the RS-fMRI signal. These indices demonstrated TE dependency of connectivity-related fluctuation strength, resembling functional contrasts in activation-based fMRI. These findings further confirm that large-scale functional circuit connectivity based on BOLD contrast may be constrained within specific frequency ranges in every brain network, and the spectral features of S(0) and T(2)(*) could be valuable for interpreting and quantifying RS-fMRI data.

Original languageEnglish
Pages (from-to)3075-84
Number of pages10
JournalNeuroImage
Volume59
Issue number4
DOIs
Publication statusPublished - Feb 15 2012
Externally publishedYes

Fingerprint

Magnetic Resonance Imaging
Noise
Brain

Keywords

  • Brain
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Physiological Phenomena
  • Sensitivity and Specificity
  • Young Adult
  • Journal Article
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

Cite this

TE-dependent spatial and spectral specificity of functional connectivity. / Wu, Changwei W; Gu, Hong; Zou, Qihong; Lu, Hanbing; Stein, Elliot A; Yang, Yihong.

In: NeuroImage, Vol. 59, No. 4, 15.02.2012, p. 3075-84.

Research output: Contribution to journalArticle

Wu, Changwei W ; Gu, Hong ; Zou, Qihong ; Lu, Hanbing ; Stein, Elliot A ; Yang, Yihong. / TE-dependent spatial and spectral specificity of functional connectivity. In: NeuroImage. 2012 ; Vol. 59, No. 4. pp. 3075-84.
@article{4b69e9c9e5594d0fa00e5a57595fea94,
title = "TE-dependent spatial and spectral specificity of functional connectivity",
abstract = "Previous studies suggest that spontaneous fluctuations in the resting-state fMRI (RS-fMRI) signal may reflect fluctuations in transverse relaxation time (T(2)(*)) rather than spin density (S(0)). However, such S(0) and T(2)(*) features have not been well characterized. In this study, spatial and spectral characteristics of functional connectivity on sensorimotor, default-mode, dorsal attention, and primary visual systems were examined using a multiple gradient-echo sequence at 3T. In the spatial domain, we found broad, local correlations at short echo times (TE ≤ 14 ms) due to dominant S(0) contribution, whereas long-range connections mediated by T(2)(*) became explicit at TEs longer than 22 ms. In the frequency domain, compared with the flat spectrum of S(0), spectral power of the T(2)(*)-weighted signal elevated significantly with increasing TE, particularly in the frequency ranges of 0.008-0.023 Hz and 0.037-0.043 Hz. Using the S(0) spectrum as a reference, we propose two indices to measure spectral signal change (SSC) and spectral contrast-to-noise ratio (SCNR), respectively, for quantifying the RS-fMRI signal. These indices demonstrated TE dependency of connectivity-related fluctuation strength, resembling functional contrasts in activation-based fMRI. These findings further confirm that large-scale functional circuit connectivity based on BOLD contrast may be constrained within specific frequency ranges in every brain network, and the spectral features of S(0) and T(2)(*) could be valuable for interpreting and quantifying RS-fMRI data.",
keywords = "Brain, Female, Humans, Magnetic Resonance Imaging, Male, Physiological Phenomena, Sensitivity and Specificity, Young Adult, Journal Article, Research Support, N.I.H., Intramural, Research Support, Non-U.S. Gov't",
author = "Wu, {Changwei W} and Hong Gu and Qihong Zou and Hanbing Lu and Stein, {Elliot A} and Yihong Yang",
note = "Published by Elsevier Inc.",
year = "2012",
month = "2",
day = "15",
doi = "10.1016/j.neuroimage.2011.11.030",
language = "English",
volume = "59",
pages = "3075--84",
journal = "NeuroImage",
issn = "1053-8119",
publisher = "Academic Press Inc.",
number = "4",

}

TY - JOUR

T1 - TE-dependent spatial and spectral specificity of functional connectivity

AU - Wu, Changwei W

AU - Gu, Hong

AU - Zou, Qihong

AU - Lu, Hanbing

AU - Stein, Elliot A

AU - Yang, Yihong

N1 - Published by Elsevier Inc.

PY - 2012/2/15

Y1 - 2012/2/15

N2 - Previous studies suggest that spontaneous fluctuations in the resting-state fMRI (RS-fMRI) signal may reflect fluctuations in transverse relaxation time (T(2)(*)) rather than spin density (S(0)). However, such S(0) and T(2)(*) features have not been well characterized. In this study, spatial and spectral characteristics of functional connectivity on sensorimotor, default-mode, dorsal attention, and primary visual systems were examined using a multiple gradient-echo sequence at 3T. In the spatial domain, we found broad, local correlations at short echo times (TE ≤ 14 ms) due to dominant S(0) contribution, whereas long-range connections mediated by T(2)(*) became explicit at TEs longer than 22 ms. In the frequency domain, compared with the flat spectrum of S(0), spectral power of the T(2)(*)-weighted signal elevated significantly with increasing TE, particularly in the frequency ranges of 0.008-0.023 Hz and 0.037-0.043 Hz. Using the S(0) spectrum as a reference, we propose two indices to measure spectral signal change (SSC) and spectral contrast-to-noise ratio (SCNR), respectively, for quantifying the RS-fMRI signal. These indices demonstrated TE dependency of connectivity-related fluctuation strength, resembling functional contrasts in activation-based fMRI. These findings further confirm that large-scale functional circuit connectivity based on BOLD contrast may be constrained within specific frequency ranges in every brain network, and the spectral features of S(0) and T(2)(*) could be valuable for interpreting and quantifying RS-fMRI data.

AB - Previous studies suggest that spontaneous fluctuations in the resting-state fMRI (RS-fMRI) signal may reflect fluctuations in transverse relaxation time (T(2)(*)) rather than spin density (S(0)). However, such S(0) and T(2)(*) features have not been well characterized. In this study, spatial and spectral characteristics of functional connectivity on sensorimotor, default-mode, dorsal attention, and primary visual systems were examined using a multiple gradient-echo sequence at 3T. In the spatial domain, we found broad, local correlations at short echo times (TE ≤ 14 ms) due to dominant S(0) contribution, whereas long-range connections mediated by T(2)(*) became explicit at TEs longer than 22 ms. In the frequency domain, compared with the flat spectrum of S(0), spectral power of the T(2)(*)-weighted signal elevated significantly with increasing TE, particularly in the frequency ranges of 0.008-0.023 Hz and 0.037-0.043 Hz. Using the S(0) spectrum as a reference, we propose two indices to measure spectral signal change (SSC) and spectral contrast-to-noise ratio (SCNR), respectively, for quantifying the RS-fMRI signal. These indices demonstrated TE dependency of connectivity-related fluctuation strength, resembling functional contrasts in activation-based fMRI. These findings further confirm that large-scale functional circuit connectivity based on BOLD contrast may be constrained within specific frequency ranges in every brain network, and the spectral features of S(0) and T(2)(*) could be valuable for interpreting and quantifying RS-fMRI data.

KW - Brain

KW - Female

KW - Humans

KW - Magnetic Resonance Imaging

KW - Male

KW - Physiological Phenomena

KW - Sensitivity and Specificity

KW - Young Adult

KW - Journal Article

KW - Research Support, N.I.H., Intramural

KW - Research Support, Non-U.S. Gov't

U2 - 10.1016/j.neuroimage.2011.11.030

DO - 10.1016/j.neuroimage.2011.11.030

M3 - Article

C2 - 22119650

VL - 59

SP - 3075

EP - 3084

JO - NeuroImage

JF - NeuroImage

SN - 1053-8119

IS - 4

ER -