Action-Based Body Maps in the Spinal Cord Emerge from a Transitory Floating Organization

TLDR

During development, primary afferents grow into the spinal cord and form topographically organized connections in the dorsal horn, yet the mechanisms guiding this intricate pathfinding remain largely unknown. The study aims to demonstrate that a body representation linked to motor patterns emerges from a transient floating and plastic organization in the spinal cord. This occurs through activity‑dependent rewiring that includes sprouting and elimination of afferent connections and cross‑modality interactions aligning multisensory input. Thus, the dorsal horn is not a fixed, inborn structure but a highly adaptive brain–body interface.

Abstract

During development primary afferents grow into and establish neuronal connections in the spinal cord, thereby forming the basis for how we perceive sensory information and control our movements. In the somatosensory system, myriads of primary afferents, conveying information from different body locations and sensory modalities, get organized in the dorsal horn of the spinal cord so that spinal multisensory circuits receive topographically ordered information. How this intricate pathfinding is brought about during development is, however, largely unknown. Here we show that a body representation closely related to motor patterns emerges from a transitory floating and plastic organization through profound activity-dependent rewiring, involving both sprouting and elimination of afferent connections, and provide evidence for cross-modality interactions in the alignment of the multisensory input. Thus, far from being inborn and stereotypic, the dorsal horn of the spinal cord now appears to be a highly adaptive brain–body interface.