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Resting state functional connectivity in the human spinal cord.

Barry RL, Smith SA, Dula AN, Gore JC - Elife (2014)

Bottom Line: Functional magnetic resonance imaging using blood oxygenation level dependent (BOLD) contrast is well established as one of the most powerful methods for mapping human brain function.However, to date there have been no previous substantiated reports of resting state correlations in the spinal cord.In a cohort of healthy volunteers, we observed robust functional connectivity between left and right ventral (motor) horns, and between left and right dorsal (sensory) horns.

View Article: PubMed Central - PubMed

Affiliation: Vanderbilt University Institute of Imaging Science, Nashville, United States Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, United States robert.l.barry@vanderbilt.edu.

No MeSH data available.


Related in: MedlinePlus

Examples of within-slice resting state functional connectivity across subjects.These analyses were performed using AFNI's ‘InstaCorr’ with p < 0.001 and no minimum cluster size. In each panel, a seed voxel is marked with a green crosshair and resultant correlations are overlaid on the anatomical image. (A)–(F) Connectivity between ventral horns for subjects 1, 3, 8, 10, 11, and 13, respectively. (G)–(J) Connectivity between dorsal horns for subjects 5, 16, 18, and 22, respectively. (K and L) Less common correlations within gray matter. In (K) (subject 20), focal connectivity between ventral horns and with central gray matter. In (L) (subject 7), connectivity between ventral horns but also with the contralateral dorsal horn. At the single-subject level, there is some evidence for functional connectivity between ventral and dorsal horns, but such correlations are less common across slices and not statistically significant at the group level.DOI:http://dx.doi.org/10.7554/eLife.02812.006
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fig4: Examples of within-slice resting state functional connectivity across subjects.These analyses were performed using AFNI's ‘InstaCorr’ with p < 0.001 and no minimum cluster size. In each panel, a seed voxel is marked with a green crosshair and resultant correlations are overlaid on the anatomical image. (A)–(F) Connectivity between ventral horns for subjects 1, 3, 8, 10, 11, and 13, respectively. (G)–(J) Connectivity between dorsal horns for subjects 5, 16, 18, and 22, respectively. (K and L) Less common correlations within gray matter. In (K) (subject 20), focal connectivity between ventral horns and with central gray matter. In (L) (subject 7), connectivity between ventral horns but also with the contralateral dorsal horn. At the single-subject level, there is some evidence for functional connectivity between ventral and dorsal horns, but such correlations are less common across slices and not statistically significant at the group level.DOI:http://dx.doi.org/10.7554/eLife.02812.006

Mentions: Functional images were preprocessed to mitigate rigid-body motion and physiological noise, and spatially interpolated to match the digital resolution of the T2*-weighted anatomical images (Figure 2). A 14-step standardized analysis protocol (described in 'Materials and methods') was used for each of the 22 subjects studied. In each subject, temporal signal-to-noise ratio (TSNR) was measured in spinal gray matter upon completion of the functional-to-anatomical affine registration (step #9) as well as after the application of CSF and white matter ‘regressors of no interest’ (steps #11 and #12). Across all 22 subjects, we observed a 30% increase in median TSNR (from 29.3 to 38.1) after the application of these few regressors, demonstrating the importance of characterizing and removing structured noise sources (Xie et al., 2012). After band-pass filtering to isolate the frequency range of interest (0.01–0.08 Hz), single-subject analyses show that statistically significant correlations are measurable between selected regions and are reproducible across subjects. As an illustrative example with the corresponding time series, an analysis performed on one subject (female, 23 years old) demonstrates connectivity with the contralateral ventral horns in the same slice and with adjacent slices when a seed region is selected in the center of the right ventral horn (Figure 3). A stringent threshold of /z/ > 3.29 (a two-tailed 99.9% confidence interval) was selected to show that connectivity is focused in the gray matter horns and not in central gray matter (connecting left and right sides and largely dominated by the central canal) nor adjacent white matter, which provides evidence that such gray matter correlations cannot be simply attributed to spatially correlated physiological noise and more likely represent genuine functional connectivity. Further examples of within-slice connectivity analyses in single subjects confirm that reproducible focal connectivity is found between ventral horns (Figure 4A–F) and between dorsal horns (Figure 4G–J). There is also evidence of plausible connectivity with central gray matter (Figure 4K) and between ventral and dorsal horns (Figure 4L), but these correlations are less consistent across all slices and not statistically significant at the group level. To quantify the occurrence of within-slice correlations between gray matter sub-regions across slices, we averaged time courses within each respective gray matter sub-region (defined in step #14) and considered only positive correlations at a more conventional 95% confidence interval (z > 1.65; one-tailed). Across all 264 slices (12 slices/subject × 22 subjects), we observed that 67% of slices (177 of 264) exhibit significant correlations between ventral horns and 37% of slices (97 of 264) exhibit significant correlations between dorsal horns. In comparison, a markedly fewer number of slices (only 1 in 5) exhibited significant correlations between the remaining four pairs: 21% between left ventral and left dorsal horns (55 of 264), 21% between left ventral and right dorsal horns (55 of 264), 20% between right ventral and left dorsal horns (54 of 264), and 23% between right ventral and right dorsal horns (62 of 264).10.7554/eLife.02812.004Figure 2.Functional weighted spinal cord images at 7 Tesla.


Resting state functional connectivity in the human spinal cord.

Barry RL, Smith SA, Dula AN, Gore JC - Elife (2014)

Examples of within-slice resting state functional connectivity across subjects.These analyses were performed using AFNI's ‘InstaCorr’ with p < 0.001 and no minimum cluster size. In each panel, a seed voxel is marked with a green crosshair and resultant correlations are overlaid on the anatomical image. (A)–(F) Connectivity between ventral horns for subjects 1, 3, 8, 10, 11, and 13, respectively. (G)–(J) Connectivity between dorsal horns for subjects 5, 16, 18, and 22, respectively. (K and L) Less common correlations within gray matter. In (K) (subject 20), focal connectivity between ventral horns and with central gray matter. In (L) (subject 7), connectivity between ventral horns but also with the contralateral dorsal horn. At the single-subject level, there is some evidence for functional connectivity between ventral and dorsal horns, but such correlations are less common across slices and not statistically significant at the group level.DOI:http://dx.doi.org/10.7554/eLife.02812.006
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4120419&req=5

fig4: Examples of within-slice resting state functional connectivity across subjects.These analyses were performed using AFNI's ‘InstaCorr’ with p < 0.001 and no minimum cluster size. In each panel, a seed voxel is marked with a green crosshair and resultant correlations are overlaid on the anatomical image. (A)–(F) Connectivity between ventral horns for subjects 1, 3, 8, 10, 11, and 13, respectively. (G)–(J) Connectivity between dorsal horns for subjects 5, 16, 18, and 22, respectively. (K and L) Less common correlations within gray matter. In (K) (subject 20), focal connectivity between ventral horns and with central gray matter. In (L) (subject 7), connectivity between ventral horns but also with the contralateral dorsal horn. At the single-subject level, there is some evidence for functional connectivity between ventral and dorsal horns, but such correlations are less common across slices and not statistically significant at the group level.DOI:http://dx.doi.org/10.7554/eLife.02812.006
Mentions: Functional images were preprocessed to mitigate rigid-body motion and physiological noise, and spatially interpolated to match the digital resolution of the T2*-weighted anatomical images (Figure 2). A 14-step standardized analysis protocol (described in 'Materials and methods') was used for each of the 22 subjects studied. In each subject, temporal signal-to-noise ratio (TSNR) was measured in spinal gray matter upon completion of the functional-to-anatomical affine registration (step #9) as well as after the application of CSF and white matter ‘regressors of no interest’ (steps #11 and #12). Across all 22 subjects, we observed a 30% increase in median TSNR (from 29.3 to 38.1) after the application of these few regressors, demonstrating the importance of characterizing and removing structured noise sources (Xie et al., 2012). After band-pass filtering to isolate the frequency range of interest (0.01–0.08 Hz), single-subject analyses show that statistically significant correlations are measurable between selected regions and are reproducible across subjects. As an illustrative example with the corresponding time series, an analysis performed on one subject (female, 23 years old) demonstrates connectivity with the contralateral ventral horns in the same slice and with adjacent slices when a seed region is selected in the center of the right ventral horn (Figure 3). A stringent threshold of /z/ > 3.29 (a two-tailed 99.9% confidence interval) was selected to show that connectivity is focused in the gray matter horns and not in central gray matter (connecting left and right sides and largely dominated by the central canal) nor adjacent white matter, which provides evidence that such gray matter correlations cannot be simply attributed to spatially correlated physiological noise and more likely represent genuine functional connectivity. Further examples of within-slice connectivity analyses in single subjects confirm that reproducible focal connectivity is found between ventral horns (Figure 4A–F) and between dorsal horns (Figure 4G–J). There is also evidence of plausible connectivity with central gray matter (Figure 4K) and between ventral and dorsal horns (Figure 4L), but these correlations are less consistent across all slices and not statistically significant at the group level. To quantify the occurrence of within-slice correlations between gray matter sub-regions across slices, we averaged time courses within each respective gray matter sub-region (defined in step #14) and considered only positive correlations at a more conventional 95% confidence interval (z > 1.65; one-tailed). Across all 264 slices (12 slices/subject × 22 subjects), we observed that 67% of slices (177 of 264) exhibit significant correlations between ventral horns and 37% of slices (97 of 264) exhibit significant correlations between dorsal horns. In comparison, a markedly fewer number of slices (only 1 in 5) exhibited significant correlations between the remaining four pairs: 21% between left ventral and left dorsal horns (55 of 264), 21% between left ventral and right dorsal horns (55 of 264), 20% between right ventral and left dorsal horns (54 of 264), and 23% between right ventral and right dorsal horns (62 of 264).10.7554/eLife.02812.004Figure 2.Functional weighted spinal cord images at 7 Tesla.

Bottom Line: Functional magnetic resonance imaging using blood oxygenation level dependent (BOLD) contrast is well established as one of the most powerful methods for mapping human brain function.However, to date there have been no previous substantiated reports of resting state correlations in the spinal cord.In a cohort of healthy volunteers, we observed robust functional connectivity between left and right ventral (motor) horns, and between left and right dorsal (sensory) horns.

View Article: PubMed Central - PubMed

Affiliation: Vanderbilt University Institute of Imaging Science, Nashville, United States Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, United States robert.l.barry@vanderbilt.edu.

No MeSH data available.


Related in: MedlinePlus