Axons of Individual Dorsal Horn Neurons Bifurcated to Project in Both the Anterolateral and the Postsynaptic Dorsal Column Systems

• Published in: Neuroscience Vol. 371; pp. 178 - 190
• Main Authors: Condés-Lara, M., Martínez-Lorenzana, G., Rojas-Piloni, G., Tello-García, I.A., Manzano-García, A., Rubio-Beltran, E., González-Hernández, A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 10.02.2018
• Subjects: anatomical and electrophysiological study; Animals; Axons - physiology; bilateral and bifurcated cells; collision test; Lumbar Vertebrae; Male; Medulla Oblongata - cytology; Medulla Oblongata - physiology; Neural Pathways - cytology; Neural Pathways - physiology; Neuroanatomical Tract-Tracing Techniques; Posterior Horn Cells - cytology; Posterior Horn Cells - physiology; Rats, Sprague-Dawley; Rats, Wistar; retrograde tracers; spinal projecting cells; Ventral Thalamic Nuclei - cytology; Ventral Thalamic Nuclei - physiology; FG; RT; WDR; EEG; AL; FR; bilateral and bifurcated cells; TB; ZI; DC-ML; STT; VPL; AV; spinal projecting cells; VL; GRA; anti-anti; retrograde tracers; collision test; Anti; CUN; anatomical and electrophysiological study; LDV; Po
• ISSN: 0306-4522; 1873-7544; 1873-7544
• DOI: 10.1016/j.neuroscience.2017.11.050

[Display omitted] •Spinal neurons project to both spino-thalamic and dorsal column systems.•Projecting cells could provide a discriminative information working as a comparator.•Electrophysiological studies support the anatomical findings. Sensory information stimulates receptors of somatosensory system neurons generating a signal that codifies the characteristics of peripheral stimulation. This information reaches the spinal cord and is relayed to supra-spinal structures through two main systems: the postsynaptic dorsal column-medial lemniscal (DC-ML) and the anterolateral (AL) systems. From the classical point of view, the DC-ML has an ipsilateral ascending pathway to the Gracilis (GRA) or Cuneate (CUN) nuclei and the AL has a contralateral ascending pathway to the ventral posterolateral (VPL) thalamic nucleus. These two systems have been the subject of multiple studies that established their independence and interactions. To analyze the ascending projections of L1–L5 spinal dorsal horn neurons in the rat, two retrograde neuronal tracers were injected into the GRA and the VPL. Additionally, an electrophysiological study was performed by applying electrical stimulation at the GRA or VPL and recording antidromic evoked activity in single unit spinal cord cells. Importantly, a subset of spinal dorsal horn neurons exhibited double staining, indicating that these neurons projected to both the GRA and the VPL. These double-stained neurons were located on both sides of the dorsal horn of the spinal cord. The spinal dorsal horn neurons exhibited antidromic and collision activities in response to both GRA and VPL electrical activation. These results show spinal cord neurons with bifurcated bilateral projections to both the DC-ML and AL systems. Based on these results, we named these neurons bilateral and bifurcated cells.