TY - JOUR
T1 - Effects of transcutaneous spinal stimulation on spatiotemporal cortical activation patterns
T2 - A proof-of-concept EEG study
AU - Steele, Alexander G.
AU - Manson, Gerome A.
AU - Horner, Philip J.
AU - Sayenko, Dimitry G.
AU - Contreras-Vidal, Jose L.
N1 - Funding Information:
The authors would like to acknowledge Justin A Brantley, PhD and David Eguren, from the University of Houston’s Noninvasive Brain-Machine Interface Systems Laboratory, for assistance in equipment testing and troubleshooting. We also thank Ms. Rachel Markley for her invaluable administrative support and assistance for this project. This work was supported by the IUCRC BRAIN (National Science Foundation Award # 1650536) to J L C-V, and philanthropic funding from Paula and Rusty Walter and the Walter Oil & Gas Corporation as well as by TIRR Mission Connect Grant No. #019-102–Jerry Johnston Andrew Award to D G S. The funders were not involved in the design of the study, the collection, analysis, and interpretation of the experimental data, the writing of this article, or the decision to submit this article for publication.
Publisher Copyright:
© 2022 The Author(s). Published by IOP Publishing Ltd.
PY - 2022/7/1
Y1 - 2022/7/1
N2 - Objective. Transcutaneous spinal cord stimulation (TSS) has been shown to be a promising non-invasive alternative to epidural spinal cord stimulation for improving outcomes of people with spinal cord injury (SCI). However, studies on the effects of TSS on cortical activation are limited. Our objectives were to evaluate the spatiotemporal effects of TSS on brain activity, and determine changes in functional connectivity under several different stimulation conditions. As a control, we also assessed the effects of functional electrical stimulation (FES) on cortical activity. Approach. Non-invasive scalp electroencephalography (EEG) was recorded during TSS or FES while five neurologically intact participants performed one of three lower-limb tasks while in the supine position: (1) A no contraction control task, (2) a rhythmic contraction task, or (3) a tonic contraction task. After EEG denoising and segmentation, independent components (ICs) were clustered across subjects to characterize sensorimotor networks in the time and frequency domains. ICs of the event related potentials (ERPs) were calculated for each cluster and condition. Next, a Generalized Partial Directed Coherence (gPDC) analysis was performed on each cluster to compare the functional connectivity between conditions and tasks. Main results. IC analysis of EEG during TSS resulted in three clusters identified at Brodmann areas (BA) 9, BA 6, and BA 4, which are areas associated with working memory, planning, and movement control. Lastly, we found significant (p < 0.05, adjusted for multiple comparisons) increases and decreases in functional connectivity of clusters during TSS, but not during FES when compared to the no stimulation conditions. Significance. The findings from this study provide evidence of how TSS recruits cortical networks during tonic and rhythmic lower limb movements. These results have implications for the development of spinal cord-based computer interfaces, and the design of neural stimulation devices for the treatment of pain and sensorimotor deficit.
AB - Objective. Transcutaneous spinal cord stimulation (TSS) has been shown to be a promising non-invasive alternative to epidural spinal cord stimulation for improving outcomes of people with spinal cord injury (SCI). However, studies on the effects of TSS on cortical activation are limited. Our objectives were to evaluate the spatiotemporal effects of TSS on brain activity, and determine changes in functional connectivity under several different stimulation conditions. As a control, we also assessed the effects of functional electrical stimulation (FES) on cortical activity. Approach. Non-invasive scalp electroencephalography (EEG) was recorded during TSS or FES while five neurologically intact participants performed one of three lower-limb tasks while in the supine position: (1) A no contraction control task, (2) a rhythmic contraction task, or (3) a tonic contraction task. After EEG denoising and segmentation, independent components (ICs) were clustered across subjects to characterize sensorimotor networks in the time and frequency domains. ICs of the event related potentials (ERPs) were calculated for each cluster and condition. Next, a Generalized Partial Directed Coherence (gPDC) analysis was performed on each cluster to compare the functional connectivity between conditions and tasks. Main results. IC analysis of EEG during TSS resulted in three clusters identified at Brodmann areas (BA) 9, BA 6, and BA 4, which are areas associated with working memory, planning, and movement control. Lastly, we found significant (p < 0.05, adjusted for multiple comparisons) increases and decreases in functional connectivity of clusters during TSS, but not during FES when compared to the no stimulation conditions. Significance. The findings from this study provide evidence of how TSS recruits cortical networks during tonic and rhythmic lower limb movements. These results have implications for the development of spinal cord-based computer interfaces, and the design of neural stimulation devices for the treatment of pain and sensorimotor deficit.
KW - EEG
KW - EEG source reconstruction
KW - cortical activation
KW - functional connectivity
KW - movement
KW - spinal cord
KW - spinal stimulation
KW - Spinal Cord Injuries
KW - Humans
KW - Electroencephalography
KW - Spinal Cord Stimulation/methods
KW - Movement/physiology
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U2 - 10.1088/1741-2552/ac7b4b
DO - 10.1088/1741-2552/ac7b4b
M3 - Article
C2 - 35732141
AN - SCOPUS:85134014960
SN - 1741-2560
VL - 19
JO - Journal of neural engineering
JF - Journal of neural engineering
IS - 4
M1 - 046001
ER -