What is the laminar organization of the dorsal horn of the spinal cord?
The dorsal horn of the spinal cord can be divided into distinct laminae based on cytoarchitectural grounds, using traditional cell (Nissl) stains. This anatomic organization is paralleled by a physiologic laminar organization. Neurons in laminae I and II, the substantia gelatinosa, respond either exclusively to noxious stimulation or to both noxious and nonnoxious stimuli. Neurons in laminae III and IV, the nucleus proprius, predominantly respond to nonnoxious stimuli. The majority of neurons in lamina V are of the wide dynamic range type (i.e., they respond to both nonnoxious and noxious stimuli and have visceral afferent inputs). Neurons in lamina VI respond predominantly to nonnoxious manipulation of joints.