Segmental and descending control of primary afferent input to the spinal lamina X

• Published in: Pain (Amsterdam) Vol. 163; no. 10; pp. 2014 - 2020
• Main Authors: Krotov, Volodymyr, Agashkov, Kirill, Krasniakova, Marharyta, Safronov, Boris V., Belan, Pavel, Voitenko, Nana
• Format: Journal Article
• Language: English
• Published: United States Wolters Kluwer 01.10.2022
• Subjects: Action Potentials - physiology; Afferent Pathways - physiology; Excitatory Postsynaptic Potentials - physiology; Gray Matter; Neurons; Neurons, Afferent - physiology; Nociception - physiology; Research Paper; Spinal Cord - physiology
• ISSN: 0304-3959; 1872-6623; 1872-6623
• DOI: 10.1097/j.pain.0000000000002597

Despite being involved in a number of functions, such as nociception and locomotion, spinal lamina X remains one of the least studied central nervous system regions. Here, we show that Aδ- and C-afferent inputs to lamina X neurons are presynaptically inhibited by homo- and heterosegmental afferents as well as by descending fibers from the corticospinal tract, dorsolateral funiculus, and anterior funiculus. Activation of descending tracts suppresses primary afferent-evoked action potentials and also elicits excitatory (mono- and polysynaptic) and inhibitory postsynaptic responses in lamina X neurons. Thus, primary afferent input to lamina X is subject to both spinal and supraspinal control being regulated by at least 5 distinct pathways.