Biology subjects

Koch, S. C.

Publications and source records attributed to Koch, S. C..

4 recordsLinked to original sources

bioRxiv2026

Postnatal development of somatosensory corticospinal projections in the mouse lumbar spinal cord

Corticospinal projections from the primary somatosensory cortex (S1) form a distinct descending pathway that engages spinal dorsal horn circuits and modulates sensory processing. Despite advances in our understanding of the role of this pathway in the adult, the postnatal maturation of somatosensory corticospinal projections remains poorly defined. Here, we provide a quantitative anatomical analysis of the postnatal development of corticospinal projections from the hindlimb representation of S1 (S1hl) to the lumbar dorsal horn in mice. Using retrograde tracing, we show that lumbar-projecting S1hl corticospinal neurons are first detected at postnatal day (P) 9 and reach adult-like numbers in S1hl by P12. Using anterograde tracing we then show that S1hl CST axonal projections are initially confined to the dorsolateral funiculus when they reach the lumbar cord at P9, but then rapidly invade the lumbar dorsal horn, reaching peak grey matter terminal density at P14. During this early innervation period, projections transiently extend beyond their mature termination zones in laminae III-V before retracting and becoming confined to superficial laminae I-II by P17. Together, these findings define three developmental phases of somatosensory corticospinal dorsal horn connections: an initial arrival phase, followed by grey matter ingrowth, and finally laminar refinement of the terminal projections. These results provide an anatomical framework for understanding how descending corticospinal somatosensory control becomes integrated into spinal circuits during the early postnatal period.

neuroscience↗

bioRxiv2025

Discrete and sequential critical periods organise the development of task-specific sensorimotor circuits in mice

Somatosensory circuits in early life must maintain stable, task-selective pathways while behavioural repertoires undergo rapid change. How such circuits construct these behaviours under evolving functional demands has remained unclear. Here we show that sensorimotor behaviours are shaped through sequential, experience-dependent critical periods rather than a single global window of plasticity. Using transient perturbations of somatosensory input across postnatal development in mice, we identify three discrete life stages that exert lasting effects on adult behaviour. Perturbation during postnatal days 8-12 selectively increases adult sensitivity to dynamic touch. The same manipulation during days 13-17 produces persistent deficits in motor coordination. Perturbation during days 18-22 instead results in lifelong impairments in skilled locomotion. These findings reveal that somatosensory circuits undergo multiple phases of refinement, each aligned with the changing functional needs of the developing organism. This framework of sequential, task-specific critical periods offers a new model for building lifelong sensorimotor function. Significance StatementDeveloping sensory systems must construct precise neural circuits to support dynamic behaviours that change with postnatal experience. We show that somatosensory circuits achieve this through sequential, task-specific critical periods, rather than a single fixed window of plasticity. This dynamic framework demonstrates how experience can guide the stepwise construction of sensorimotor behaviours, offering a new perspective on critical periods across complex, multimodal systems.

neuroscience↗

bioRxiv2025

Ethologically relevant behavioural assay for investigating reach and grasp kinematics during whole-body motor control in mice

Reach and grasp are critical components of skilled mammalian motor control and their detailed analysis in rodents has been key to deepening our understanding of prehension in the context of health and disease. However, most studies investigating these behaviours focus on isolating forelimb movements with little regard to the whole-body movements that are key for effective behaviour. To address this issue, we designed a novel behavioural approach to investigate reach and grasp during whole-body, vertical locomotion in mice. Using a customizable transparent climbing surface, we show that our behavioural approach can extract key kinematic features of climbing. Mouse climbing gait reflects aspects of quadrupedal locomotion, showing similar phase dependencies on increasing speed, including reduced stance (i.e. grasp) time and duty factor. Analysis of multi-limb coordination indicated that climbing revolves around anti-phasic forepaw movements with less consistency in interlimb coordination in the hindpaws. Fore- and hindpaws also differed in their reach trajectories and velocity profiles. The flexibility of this approach also allows for tailored climbing configurations, which we use to show that mice can adapt to and overcome vertical obstacles. By leveraging naturalistic climbing, our modular behavioural approach enables investigation of complex prehensile behaviours and facilitates new study into the neural circuits underlying whole-body skilled motor control.

neuroscience↗

bioRxiv2020

A Harmonized Atlas of Spinal Cord Cell Types and Their Computational Classification

Single cell sequencing is transforming many fields of science but the vast amount of data it creates has the potential to both illuminate and obscure underlying biology. To harness the exciting potential of single cell data for the study of the mouse spinal cord, we have created a harmonized atlas of spinal cord transcriptomic cell types that unifies six independent and disparate studies into one common analysis. With the power of this large and diverse dataset, we reveal spinal cord cell type organization, validate a combinatorial set of markers for in-tissue spatial gene expression analysis, and optimize the computational classification of spinal cord cell types based on transcriptomic data. This work provides a comprehensive resource with unprecedented resolution of spinal cord cell types and charts a path forward for how to utilize transcriptomic data to expand our knowledge of spinal cord biology.

neuroscience↗