Professor Pierre Lledo describes how odorant molecules (smells) are processed in the olfactory system. The process relies heavily on spatial maps.
How the brain perceives and detects and memorizes odor information has been a long-lasting debate. Even today, we are not sure about how the brain recognizes odorant molecules from outside. But we can guess. We know, first of all, that the odorant molecules are recognized by sensory organs that are located in the nostril. From there, there is a transformation of the information from chemical to electrical information. Then this electrical information reaches the brain and basically our brain knows what we are smelling according to where these sensory inputs are reaching the brain. We call these, spatial maps. The important dimension here, is the spatial one – where information is occurring into the brain.
How this spatial dimension is then going to move and bring information to higher centers, we don’t know. But we can guess. One of the major candidates is, in fact, the temporal dimension. From a spatial dimension, where you have maps, and what we call odorant maps – images if you want – these images are going to be transformed into temporal information. Not only does the brain need to know where this information occurs in the brain, but also when [it occurs]. The 'when' is very important because in the temporal dimension you might be able to discriminate very similar odorants.
We spend much of our lives eating, view our sense of taste primarily as a source of pleasure—and perhaps a lamentable temptation to excess. Taste is also a vigilant gatekeeper of the body, evolved to reject what is harmful.