科学家们现在绘制出了大脑中4个感官热区，每个感官热区用于处理一种基本的味觉：甜、咸、苦及鲜味。
大脑中的味觉图
在过去的50年中，科学家们已经绘制出了其它的感觉比较图谱。 他们在皮层中发现了与视觉、听觉、触觉有关的神经元网络；他们的研究显示，嗅觉涉及到一个更为稀疏、分散的神经元活动。 但是，味觉一直仍然还是一个谜。
Xiaoke Chen及其同事如今用一种叫做双光子钙成像的技术来寻找小鼠丘脑中的对味觉起反应的个体细胞。 然后他们追踪神经联系进入到大脑中的一个叫做脑岛的区域中的初级味觉皮层。
研究人员使用经过基因敲除的小鼠来做实验，这些小鼠的舌头中缺乏特定的味觉受体。 综合来看，这些结果为人们提供了一幅清晰的图像，显示味觉如何因每个热区对应一种单独味觉品质而在大脑中呈现。
研究者们没有找到与酸的味觉有关的热区，这可能是因为该热区位于他们所采样的区域之外，或是因为酸的刺激同时也作用于其它的诸如疼痛和触觉这样的通路。
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生物探索推荐英文摘要
Scientists have mapped out four sensory hotspots in the brain, each devoted to processing one of the basic tastes -- sweet, salty, bitter and umami. Over the last 50 years, scientists have produced comparable maps for the other senses. They’ve identified networks of neurons responsible for vision, hearing and touch have been identified in the cortex, and they’ve shown that the sense of smell involves a more sparse, spread-out pattern of neuronal activity. Taste, however, has remained a mystery. Xiaoke Chen and colleagues have now used a technique called two-photon calcium imaging to identify individual cells in the mouse thalamus that respond to taste. They then traced the neural connections into the primary taste cortex in a brain area called the insula. The researchers also conducted experiments using knockout mice lacking specific taste receptors in their tongues. Taken together, the results provide a clear picture of how taste is represented in the brain, with each hotspot corresponding to a single taste quality. The authors did not find a hotspot for the sour taste, possibly because it lies outside the area they sampled, or because acid stimuli also act on other pathways such as pain and touch.
