Article Figures & Data
Figures
- Figure 1.
Clusters of neural activity (p < 0.05 FWE cluster corrected) rendered on a standard T1 template for vibrotactile stimulation (i.e., BONE > REST) of the left (red) and right (blue) lower limbs of young and older adults. S1, Primary somatosensory cortex; SMG, supramarginal gyrus; Post Ins, posterior insula.
- Figure 2.
Clusters of neural activity (p < 0.05 FWE cluster corrected) rendered on standard T1 template for muscle spindle stimulation (i.e., TENDON > BONE) of the left (red), right (blue), and both (green) feet of young and older adults. IFG, Inferior frontal gyrus; Ant Ins, anterior insula; BG, basal ganglia; OFC, orbital frontal cortex; DLPFC, dorsolateral prefrontal cortex; SMG, supramarginal gyrus; IPC, inferior parietal cortex; PMv, premotor ventral region; S1, primary somatosensory cortex; M1, primary motor cortex.
- Figure 3.
Left, Largest cluster (green, rendered on standard MNI template) of voxels showing a significant positive correlation (FDR < 0.01) between neural activity during TENDON > BONE (i.e., muscle spindle) stimulation and balance performance (i.e., ES). Right, Clusterwise PSC for YOUNG (red) and OLD (yellow) averaged across feet correlated with ES; r values are used as a measure of strength of relationship. OFC, Orbital frontal cortex; Ant Ins, anterior insula; IFG p. tri, inferior frontal gyrus pars triangularis; IFG p. oper, inferior frontal gyrus pars opercularis; BG, basal ganglia.
- Figure 4.
Top, Second through fourth largest clusters (green, rendered on standard MNI templates at top) of voxels showing significant positive correlation (FDR < 0.01) between neural activity during TENDON > BONE (i.e., muscle spindle) stimulation and balance performance (i.e., ES). Bottom, Cross-plots of the relationship between clusterwise PSC averaged across feet and balance performance in YOUNG (red) and OLD (yellow), r values indicate strength of relation. Ant Ins, Anterior insula; SMG, supramarginal gyrus; IPC, inferior parietal cortex.
- Figure 5.
Fifth through eighth largest clusters (green, rendered on standard MNI templates) of voxels showing significant positive correlation (FDR < 0.01) between neural activity during TENDON > BONE (i.e., muscle spindle) stimulation and balance performance (i.e., ES). Next to each render, the relationship between clusterwise PSC averaged across feet and balance performance in YOUNG (red) and OLD (yellow) is cross-plotted with r values to indicate strength of relation. PMv, Premotor ventral; S2, secondary somatosensory; DLPFC, dorsolateral prefrontal cortex.
Tables
TENDON > BONE peak location Side x y z t value Cluster 1: 4205 voxels Inferior frontal gyrus (p. tri, BA 45) R 54 16 −2 5.78 Inferior frontal gyrus (p. oper, BA 44) R 52 16 16 4.97 Anterior insular lobe (BA 48) R 28 20 −8 5.63 Precentral gyrus (PMv, BA 6) R 50 10 38 5.44 R 48 4 46 4.73 R 50 6 48 4.73 Orbitofrontal cortex (BA 47) R 44 22 −14 5.07 R 48 42 −4 4.15 Basal ganglia (pallidum) R 18 0 0 4.8 R 22 0 2 4.75 Basal ganglia (putamen) R 34 10 −4 4.74 Thalamus R 14 −8 0 4.49 Cluster 2: 2142 voxels Supramarginal gyrus (BA 40) R 60 −42 42 6.10 Supramarginal gyrus (BA 40/2) R 64 −38 40 6.08 R 64 −34 30 5.57 Inferior parietal cortex (BA 40) R 60 −44 48 5.88 Cluster 3: 2123 voxels Inferior frontal gyrus (p. oper, BA 44) L −50 10 12 5.31 L −50 12 4 4.96 Anterior insular lobe L −30 20 4 5.2 L −32 20 −6 4.94 L −34 18 −8 4.94 Inferior frontal gyrus (p. tri, BA 45) L −48 16 −2 5.2 Basal ganglia (putamen) L −24 0 8 4.38 L −26 2 6 4.35 Basal ganglia (pallidum) L −16 2 2 3.79 Thalamus L −20 −6 8 4.14 Cluster 4: 1809 voxels Pre-SMA (BA 6) R 8 14 58 5.49 R 8 10 60 5.44 L −10 2 70 4.18 L −4 10 58 3.97 SMA (BA 6) R 10 −4 70 4.71 R 2 −20 72 4.22 L −10 −4 78 4.33 L −14 −6 70 4.18 L −10 −12 74 4.09 L −6 −6 64 3.85 Dorsal anterior cingulate (BA 32) R 6 22 48 5.27 R 8 26 34 4.61 Cluster 5: 938 voxels Inferior parietal cortex (BA 40) L −62 −48 40 5.31 L −60 −48 44 4.95 L −58 −44 50 4.81 L −56 −46 52 4.4 L −60 −58 34 3.65 Supramarginal gyrus (BA 40/2) L −64 −44 36 4.81 L −66 −36 32 4.04 L −60 −30 46 3.93 Supramarginal gyrus (BA 2) L −56 −24 30 4.37 L −56 −28 30 4.36 Cluster 6: 422 voxels Middle frontal gyrus (DLPFC, BA 46) R 28 50 20 4.49 R 38 40 34 4.23 -
R, Right; L, left; p. tri, pars triangularis; p. oper, pars opercularis; PMv, premotor ventral; DLPFC, dorsolateral prefrontal cortex.
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- Table 2.
Summary of mean (±SE) sway metrics for younger and older adults with p values from t test measuring YOUNG > OLD performance
Sway parameter Younger Older p value Max AP excursion (ES) 93.1 (±0.4) 91.8 (±0.5) <0.05 Max ML excursion (cm) 0.60 (±0.04) 0.67 (±0.05) 0.16 RMS AP (cm) 0.34 (±0.02) 0.4 (±0.1) 0.10 RMS ML (cm) 0.11 (±0.01) 0.13 (±0.01) 0.09 AP velocity (cm/s) 25.3 (±0.6) 29.1 (±1.8) <0.05 ML velocity (cm/s) 18.9 (±0.4) 20.2 (±0.8) 0.07 - Table 3.
List of brain areas showing significant association between muscle spindle-related brain activity (i.e. TENDON > BONE) and balance performance in terms of ES
Location of peak association with ES Side x y z t value p value Cluster 1: 2148 voxels Anterior insula R 36 20 8 4.83 0.004 R 30 30 2 3.49 0.004 R 30 26 −2 3.47 0.004 Inferior frontal gyrus (p. tri, BA 45) R 38 44 8 4.62 0.004 R 36 44 4 4.53 0.004 Orbital frontal cortex (BA 47) R 50 22 −14 4.44 0.004 Inferior frontal gyrus (p. oper, BA 44) R 48 6 14 4.37 0.004 R 54 4 2 3.96 0.004 Basal ganglia (putamen) R 20 −6 10 3.31 0.005 Basal ganglia (pallidum) R 22 −8 8 3.26 0.005 Cluster 2: 528 voxels pre-SMA (BA 6) R 8 18 68 4.13 0.004 R 8 2 70 3.72 0.004 R 8 22 58 3.45 0.004 R 2 16 48 3.19 0.006 Dorsal anterior cingulate (BA 32) R 8 24 42 2.97 0.008 R 6 28 40 2.96 0.008 Cluster 3: 404 voxels Anterior insula L −30 28 0 4.25 0.004 L −36 16 0 3.72 0.004 L −26 20 −8 3.38 0.005 Cluster 4: 347 voxels Supramarginal gyrus (BA 40) R 56 −36 44 3.63 0.004 R 54 −36 40 3.62 0.004 Cluster 5: 232 voxels Middle frontal gyrus (DLPFC, BA 46) R 32 46 16 4.22 0.004 R 26 50 22 3.90 0.004 Cluster 6: 131 voxels Middle frontal gyrus (DLPFC, BA 9) R 48 18 44 3.37 0.004 R 48 14 42 3.15 0.006 Precentral gyrus (BA 6) R 42 6 36 3.30 0.005 R 46 10 44 3.17 0.006 R 46 12 40 3.16 0.006 R 52 4 40 3.02 0.008 Cluster 7: 41 voxels Middle frontal gyrus (DLPFC, BA 46) R 38 30 32 3.71 0.004 R 36 38 34 2.99 0.008 Cluster 8: 37 voxels Parietal operculum (S2, BA 43) R 68 −20 20 3.73 0.004 -
R, Right; L, left; p. tri, pars triangularis; p. oper, pars opercularis; DLPFC, dorsolateral prefrontal cortex; S2, secondary somatosensory region.
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