CPn

CPn refers to corticopontine neurons, a class of pyramidal neurons in the neocortex that project to the pontine nuclei in the brainstem. They originate predominantly in layer 5 (and sometimes 5b) across several cortical areas, including the motor and premotor cortex, and send long-range axons to the pontine nuclei. From there, pontine neurons relay signals to the cerebellum via mossy fibers, forming a cortico-pontine-cerebellar loop that is thought to participate in planning and coordinating movements.

CPn are distinct from corticospinal neurons (CSN), which project to the spinal cord, and from corticothalamic neurons (CT), which project to the thalamus. They can exhibit different patterns of collateral projections and gene expression, reflecting their specialized roles within corticofugal pathways.

Molecularly, CPn are often associated with markers such as CTIP1 (BCL11A), helping differentiate them from CSN that commonly express CTIP2 (BCL11B). However marker expression can vary by species and brain region.

In research, CPn neurons have been studied in rodents and other mammals using tract-tracing and genetic labeling to map their contributions to motor control and learning as part of broader studies of corticofugal projection systems.