AChemS, Day 3: "How does the tongue know what it is tasting and how does the brain know what the tongue knows?"
Posted 2/8/2011 12:02 AM by Nicole Garneau | Comments
The questions pertaining to researching flavor, I'm learning, go
far beyond taste. Flavor is a combination of taste, smell and
texture. Each of the factors then send signals to the brain (at the
primary taste cortex) which allows it to form an internal
representation of the physical and chemical features of what is
Tonight I watched an exceptional presentation, from both a
scientific and entertaining viewpoint. It was an overview of
mammalian taste given by this year's IFF (International Flavors and
Fragrances Inc.) platform lecturer, Dr. Charles Zuker.
Why exactly did I enjoy this lecture so? Very simple
1. It was directional and personable. It began wide-reaching,
depicting perception of the world through each of the senses:
hearing, sight, touch, smell and of course, taste. A bit of Mozart
played in the background as the point was made that our senses
allow us to capture the surrounding world in our minds, and not
necessarily an exact picture, but a representation that allows us
to make decisions and proceed. From there the details emerged
concerning taste specifically. It was personable because the
presenter was engaging- it felt conversational, even though I was
one in a crowd of 500.
2. The story included the forest, not just the trees. I can
tell you that when my life revolved around my lab bench, it was so
easy to converse only with those that spoke the same language as I-
at that time in my life it was the sweet lexicon of viruses. And
let me tell you, when your life revolves around one very small
portion of the world at large, and you know everything, and I mean
everything about that one thing, It is easy to get lost in it. So I
truly appreciate it when a scientist is conscious of this trait and
makes an effort to present his or her research in a way that
addresses the eternal question of significance.So then, why is
taste so important? Well, you can't talk about taste without
talking about health. And our decisions about how we treat our
bodies, including what we eat, has to do with perception- the
information the brain gets and what it does with it. Dr. Zuker
aptly posed the following question:
"How does the tongue know what it is tasting and how does the
brain know what the tongue knows?"
3. It generated a healthy discourse among experts. Science is
funny, I mean it, truly funny. It is not a flowery positive world.
In science, you can almost never, in the most absolute form, prove
anything. What you can do is supply the most convincing evidence to
bring forth a story, while simultaneously disproving other stories.
This means that scientists are often uncompromising in their
criticisms. If you can't poke holes in a theory, then the theory
likely will hold up to the high standards of peer-reviewed
research. Discourse in this way is good, it keeps scientists
So, that's why I really enjoyed this talk, but not why I was
fascinated. My fascination has to do not with the style of the
presentation, but the substance.
The answers to the questions Zuker asked above about the tongue
and the brain include knowing how the receptors of taste work,
knowing how this information gets to the brain and knowing how the
brain processes this information. This last part, well, Zuker is
doing some really cool work to answer this with mice. What he has
found is that its more than just a receptor (like a lock) that
binds to a taste molecule (like a key), but it is also the
hardwiring of how these receptors activate the taste cells that
report to the brain. It turns out that if you take a bitter taste
cell and replace the bitter receptors with sweet receptors, you get
an extraordinary result: sweet compounds taste bitter!
Why is this? Well, the bitter cells are hardwired to report
bitterness to the brain (like sweet cells report only sweet to the
brain), so when the cell gets activated by one of its receptor
binding a taste molecule (like turning on a light) it reports the
light is on, regardless of how the light got turned on.
With that, It's about midnight or so here, so I think it's time
for me to turn off a few lights myself.
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