Figure 3. Labeled Lines Mediate Taste Sensation.

It is now known that tastes to sweet (red), bitter (blue), sour (green), umami (yellow), and sodium (purple) are mediated by separate populations of selectively tuned taste receptor cells. Notably, taste buds from all regions of the oral cavity contain cells that respond to the five basic modalities. Thus, contrary to popular belief, there is no topographic map (i.e., a tongue map) of taste qualities on the tongue.