PMC

Diagrams summarizing the cellular elements taking part in neurovascular coupling in the olfactory glomerulus. Left: At low input intensities, action potentials in a few olfactory nerves (ON) cause release of glutamate from terminals, which activate glutamate receptors (open rectangles) on limited numbers of postsynaptic mitral and tufted cell (M/T) dendrites, and also glutamate receptors and transporters (green spheres) on glial cells, which in turn regulate blood flow through local capillaries. Right: At high input intensities, action potentials in many ONs cause release of Glu from many hundreds to thousands of terminals, which activate corresponding numbers of M/T dendrites and also PG cell dendrites. This strong input is restrained by feedback inhibition through GABA released from PG cell dendrites. The M/T dendrites postsynaptic to axon terminals are also presynaptic and release Glu on PG cell dendrites. It is postulated that axonal and dendritic Glu summate to mediate strong activation of the glial GluRs and glutamate transporters. The glial cells in turn exert strong regulation of local capillaries to increase local blood flow, which may also affect blood flow in the capillary network to neighboring glomeruli. Adapted from , and .