Lumbosacral spinal cord functional connectivity at rest: From feasibility to reliability

Area of Science:

• Neuroimaging
• Spinal Cord Physiology
• Functional Magnetic Resonance Imaging (fMRI)

Background:

• Spontaneous blood-oxygen-level-dependent (BOLD) signal fluctuations are increasingly studied in the spinal cord, extending beyond the brain.
• Research has primarily focused on the cervical spinal cord, leaving the lumbosacral segments under-explored despite their importance in lower limb function.

Purpose of the Study:

• To confirm organized spontaneous BOLD signals in the human lumbosacral spinal cord.
• To evaluate the impact of various denoising strategies on spinal fMRI signal quality and functional connectivity (FC).

Main Methods:

• Utilized fMRI to detect spontaneous BOLD signal fluctuations in the lumbosacral spinal cord.
• Applied and compared multiple denoising strategies, including physiological noise modeling (PNM).
• Assessed signal quality and functional connectivity (FC) patterns, including split-half reliability.

Main Results:

• Confirmed the presence of organized, bilateral functional connectivity (FC) between the ventral and dorsal horns in the lumbosacral spinal cord.
• Observed consistent FC patterns across different denoising methods, demonstrating fair to excellent temporal stability.
• Physiological noise modeling (PNM)-based denoising pipelines proved effective in signal cleaning while preserving connectivity strength.

Conclusions:

• Demonstrated robust intrinsic functional connectivity (FC) patterns in the human lumbosacral spinal cord.
• Highlighted the efficacy of PNM-based denoising for reliable spinal fMRI analysis.
• Provides a foundation for future research into caudal spinal cord activity and its role in motor and sensory processing.