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Abstract

The spinal cord is the key bridge between the brain and the body. However, scientific understanding of spinal cord function has historically been limited because noninvasive measures of its neural activity have proven exceptionally challenging. In this work, we describe an enhanced recording and analysis approach, Electrical Spinal Imaging (ESI), to obtain noninvasive, high-resolution images of the electrical activity of the human spinal cord. ESI is analytically simple, easy to implement, and data-driven: it does not involve template-based strategies prone to produce spurious signals. Using this approach, we provide a detailed description and physiological characterization of the spatiotemporal dynamics of the peripheral, spinal, and cortical activity elicited by somatosensory stimulation. We also demonstrate that attention modulates postsynaptic activity at spinal cord level. Our method has enabled five important insights regarding spinal cord activity. (1) We identified three distinct responses in the time domain: sP9, sN13, and sP22. (2) The sP9 is a traveling wave reflecting the afferent volley entering the spinal cord through the dorsal root. (3) In contrast, the sN13 and sP22 reflect segmental postsynaptic activity. (4) While the sP9 response is first seen on the dorsal electrodes ipsilateral to the stimulated side, the sN13 and sP22 were not lateralized with respect to the side of stimulation. (5) Unimodal attention strongly modulates the amplitude of the sP22, but not that of the sP9 and sN13 components. The proposed method offers critical insights into the spatiotemporal dynamics of somatosensory processing within the spinal cord, paving the way for precise noninvasive functional monitoring of the spinal cord in basic and clinical neurophysiology.

Publication Date

2025-11-26

Publication Title

PLoS biology

Volume

23

Issue

11

First Page

3003116

Last Page

3003116

Deposit Date

2026-07-24

Funding

This work was funded by the European Research Council (https://erc.europa.eu; Consolidator Grant PAINSTRAT 649020 to GDI, and Proof of Concept Grant SPINREC 899963 to GDI). This work has been carried out within the Brain and Machines Flagship initiative of the Italian Institute of Technology. The funders played no role in the study design, data collection and analysis, decision to publish, and preparation of the manuscript.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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