The corticospinal tract primarily modulates sensory inputs in the mouse lumbar cord

Yunuen Moreno-Lopez (1, 2, 3) , Charlotte Bichara (1, 2, 3) , Gilles Delbecq (1, 2, 3) , Philippe Isope (1, 2, 3) , Matilde Cordero-Erausquin (1, 2, 3)

1 INCI - Institut des Neurosciences Cellulaires et Intégratives
2 CNRS - Centre National de la Recherche Scientifique
3 UNISTRA - Université de Strasbourg

It is generally assumed that the main function of the corticospinal tract (CST) is to convey motor commands to bulbar or spinal motoneurons. Yet the CST has also been shown to modulate sensory signals at their entry point in the spinal cord through primary afferent depolarization (PAD). By sequentially investigating different routes of corticofugal pathways through electrophysiological recordings and an intersectional viral strategy, we here demonstrate that motor and sensory modulation commands in mice belong to segregated paths within the CST. Sensory modulation is executed exclusively by the CST via a population of lumbar interneurons located in the deep dorsal horn. In contrast, the cortex conveys the motor command via a relay in the upper spinal cord or supraspinal motor centers. At lumbar level, the main role of the CST is thus the modulation of sensory inputs, which is an essential component of the selective tuning of sensory feedback used to ensure well-coordinated and skilled movement.

Keywords: corticospinal; mouse; neuroscience; primary afferent depolarization; sensorimotor

Domains: Life Sciences [q-bio]; Neurons and Cognition [q-bio.NC]

Yunuen Moreno-Lopez, Charlotte Bichara, Gilles Delbecq, Philippe Isope, Matilde Cordero-Erausquin. The corticospinal tract primarily modulates sensory inputs in the mouse lumbar cord. eLife, 2021, 10, ⟨10.7554/eLife.65304⟩. ⟨hal-03430331⟩