47: Mapping Wide Dynamic Range Neuron Population in Spinal Cord - High-Density Neuropixels Recordings

Topic: Basic Science
Subtopic: Non-specific to any diagnosis (including studies in healthy animals), Developing methodology/technology, Electrophysiology, Neuroanatomical circuit analysis

Background and Aims: The spinal dorsal horn is a center for integration of somatosensory processing. Therein peripheral inputs of different modalities and intensities are processed before ascending to the brain. Wide Dynamic Range (WDR) neurons play a crucial role in encoding stimulus intensity from light touch to noxious stimuli [1, 2], and are strongly engaged in mechanism described as Gate Control Theory of Pain, acting as transmission cells [3]. Most knowledge about WDR neurons comes from single-unit recordings, limiting insight into population-level organization across spinal cord. Advances in high-density electrophysiological recordings provide an opportunity to study spinal sensory processing at population level.

Methods: We performed acute in vivo extracellular recordings from lumbar (L3-L4) mice spinal cord using Neuropixels 1.0 probe combined with ONIX acquisition system. Neuronal activity was recorded during different stimulations of the ipsilateral hind paw. The protocol included light touch stimulation, increasing mechanical stimulation (by an electronic von Frey apparatus), electrical stimulation to elicit wind-up, and exposure to cold stimuli. Neuronal depth was reconstructed from probe geometry. Data were processed using Kilosort4 for spike sorting, followed by manual curation in Phy. Further analysis was carried out using a custom Python script.

Results: Neuronal populations were characterized based on their response profiles to electrical, mechanical and thermal stimulation combined with laminar location. Using multimodal response features, neurons were classified as Low Threshold, High Threshold, or WDR, with a certain degree of modality specificity. WDR neurons exhibited a gradual increase in firing rate in response to increasing mechanical force, demonstrated the wind-up, defined as an increase in firing rate during repetitive electrical stimulation of constant noxious intensity, and showed sensitivity to thermal stimuli. A network-wide response to defined stimuli was established, revealing coordinated interneuronal activity that was dependent on stimulus modality and intensity.

Conclusions: High-density Neuropixels’ recordings in the mouse spinal cord provide an unbiased, high-yield approach for identifying and mapping spinal neuron populations in vivo. Unlike classical recordings requiring active searching for individual WDR neurons, this method enables simultaneous sampling of tens to hundreds of neurons across dorsal horn laminae, capturing population-level sensory coding. Combined with genetic and pharmacological tools, this approach offers unprecedented insight into spinal neuronal processing in health and disease.

References: [1] Melzack, R., & Wall, P. D. (1965). Pain mechanisms: A new theory. Science, 150(3699), 971–979. https://doi.org/10.1126/SCIENCE.150.3699.971;WEBSITE:WEBSITE:AAAS-SITE;JOURNAL:JOURNAL:SCIENCE;WGROUP:STRING:PUBLICATION
[2] Mendell, L. M., & Wall, P. D. (1965). Responses of Single Dorsal Cord Cells to Peripheral Cutaneous Unmyelinated Fibres. Nature 1965 206:4979, 206(4979), 97–99. https://doi.org/10.1038/206097a0
[3] Price, D. D., & Dubner, R. (1977). Neurons that subserve the sensory-discriminative aspects of pain. Pain, 3(4), 307–338. https://doi.org/10.1016/0304-3959(77)90063-X

Presenting Author: Joanna Bernacka
Submitting Author: Joanna Bernacka

Senior Author: Mateusz W. Kucharczyk

IASP 2026 Global Year theme of Neuropathic Pain: No

• Joanna Bernacka: PhD - Cancer Neurophysiology Research Group, Polish Centre for Technology Development, Łukasiewicz-PORT, Wrocław, PL
• Eliza Kramarska: PhD - Cancer Neurophysiology Research Group, Polish Centre for Technology Development, Łukasiewicz-PORT, Wrocław, PL
• Mateusz W. Kucharczyk: PhD - 1Cancer Neurophysiology Research Group, Polish Centre for Technology Development, Łukasiewicz-PORT, Wrocław, PL; 2Biophotonics and Electrophysiology Lab, Bioimaging Laboratories, Center for the Development of Therapies for Civilization and Age-Related Diseases, Jagiellonian University Medical College, Kraków, PL; 3Wolfson Sensory, Pain and Regeneration Centre, King’s College London, UK