ABSTRACT
As the main cell type in mammalian cortex, cortical projection neurons play an important role in brain functions, including motor control, sensation and cognition.Projection neurons in the cerebral cortex include excitatory projection neurons and inhibitory projection neurons, of which excitatory projection neurons are the main type.Cortical excitatory projection neurons have various subtypes, and most of them have their own unique developmental rules and molecular markers.Studying the origin and classification of projection neurons in the cerebral cortex is helpful to understand the mechanisms of diseases related to abnormal projection neurons.This paper reviews the origin, classification and function of cortical projection neurons.
ABSTRACT
Electrophysiological studies have shown that the spinosolitary tract-dorsal column postsynaptic (SST-DCPS) neurons may project to both the dorsal column and solitary tract nuclei. In order to demonstrate the neurons morphologically, fluorescein dyes, PI and Bb, were injected into the dorsal column nuclei and the solitary tract nucleus respectively. A total 282 cells were found to be retrogradely labeled in the spinal dorsal horn in 10 adult rats. Of them, 51 (18%) cells were PI-Bb doubly labeled; 120 (43%) were PI labled alone; and 111 (39%) were Bb singly labled. Most of these double-labled cells were concentrated in laminae III-V. The existence of double projection neurons that project to both the dorsal column and solitary tract nuclei, namely the physiologically identified SST-DCPS neurons, is morphologically confirmed in the present study. These neurons may transmit information to both visceral and somatic sensory nuclei, indicating they may play an important role in the convergence of somato-visceral afferents.