"Big Brain: The Origins and Future of Human Intelligence"

figure 5.3

Point to point and random-access organization in the olfactory system. Arrays of neurons in the nose (A) send axons to the olfactory bulb, maintaining their spatial organization in point to point fashion. But the bulb then discards this organization, sending axons in diffuse, random-access patterns to the olfactory cortex (far right). The axons of these neurons have branches that double back into the olfactory cortex, further mixing up the already mixed-up input signals. Even though three different aroma components (C) may activate three different locations in your nose, and in the olfactory bulb, their random-access projections will intersect at various random points in cortex: cells at which the inputs converge can be used as storage sites for a unified percept (e.g., "candle" or "cabernet" or "soap").