subgranular

Subgranular is an anatomical descriptor used to designate structures located beneath the granule cell layer in certain brain regions, most commonly referring to the subgranular zone of the dentate gyrus in the hippocampus. The subgranular zone (SGZ) is a narrow cellular layer that lies at the interface between the granule cell layer and the hilus, along the inner aspect of the dentate gyrus. It forms one of the main neurogenic niches in the adult mammalian brain, housing neural progenitor cells that proliferate and differentiate into granule neurons that integrate into the dentate circuitry.

Functionally, the SGZ is notable for adult hippocampal neurogenesis, a process by which new granule neurons are generated throughout life. These neurons are thought to contribute to hippocampal plasticity, learning, and pattern separation, and may play a role in mood regulation. The rate of SGZ neurogenesis is influenced by age and a variety of environmental and physiological factors.

Factors that can modulate SGZ activity include physical exercise and environmental enrichment, which generally enhance neurogenesis, as well as certain antidepressants. Conversely, chronic stress, aging, inflammation, and some neurodegenerative conditions tend to reduce SGZ neurogenesis. The SGZ is a focus of ongoing research in neuroscience as scientists seek to understand how adult-born neurons contribute to cognition and affective states.

See also: dentate gyrus, granule cell layer, hippocampus, adult neurogenesis, neurogenesis in the SGZ.