FIGURE 4. Reciprocal connection between isofunctional glomeruli.

From the following article:

Odorant receptors instruct functional circuitry in the mouse olfactory bulb

Leonardo Belluscio, Claudia Lodovichi, Paul Feinstein, Peter Mombaerts and Lawrence C. Katz

Nature 419, 296-300(19 September 2002)



a, b, Micro-injection of tracer in the dorsolateral bulb (a) labels local external tufted cells (arrows), which form a restricted projection in the superficial granule cell layer in the medial bulb (b). c, d, Tracer injection targeted to a GFP-labelled rI7 right arrow M71 glomerulus (c, green) on the dorsolateral bulb labels both associated external tufted cells (arrows) and a specific intrabulbar projection (d, bracketed region), which is centred beneath the medial rI7 right arrow M71 glomerulus. e, Diagram of the reciprocal connection that links isofunctional glomeruli. rI7 right arrow M71 sensory neurons (green squares) form excitatory synapses (triangle) with external tufted cells (green) in the rI7 right arrow M71 glomeruli, which in turn project to the opposite side of the bulb. There, they ramify onto superficial granule cells (red), located directly below the isofunctional rI7 right arrow M71 glomerulus, which then form inhibitory synapses (circle) on overlying mitral or tufted cells23,24. Epi, epithelium; GC, granule cell; GCL, granule cell layer; GL, glomerular layer. Scale bars, 50 microm.