periglomerular

Periglomerular refers to structures or cells located around a glomerulus. In neuroscience, the term is most often applied to a class of interneurons in the olfactory bulb that surround the glomeruli within the glomerular layer.

Periglomerular (PG) interneurons are small, typically GABAergic neurons that modulate the initial synaptic processing of olfactory information. They are positioned around individual glomeruli and form synapses with the axon terminals of olfactory receptor neurons as well as with mitral and tufted cells, and with other interneurons in the region. Some PG cells also express other markers, such as dopamine, calretinin, or calbindin, reflecting cellular diversity within this population.

Morphologically, PG cells are variable but generally short in extent, with processes oriented to influence the activity within and across glomeruli. Their axons and dendrites participate in local inhibitory circuits, contributing to feedforward and lateral inhibition that shapes the input to principal output neurons of the olfactory bulb.

Developmentally, PG interneurons arise mainly from progenitors in the subventricular zone and migrate to the olfactory bulb via the rostral migratory stream, where they differentiate into multiple interneuron subtypes, including the periglomerular lineage.

Functionally, PG cells play a key role in shaping odor representations by regulating gain, contrast, and temporal dynamics of olfactory signaling. They help refine glomerular responses, contribute to odor discrimination, and participate in network oscillations within the bulb.

See also: olfactory bulb, interneurons, dopaminergic periglomerular cells.