Dr. Charles Zuker

So the first thing is that the two evoke diametrically opposed behaviors.

If we have to come up with two sensory experience that represent polar opposites, it will be sweet and bitter.

So then the signals, if we follow now these two lines, they're really like two separate keys at the two ends of this keyboard.

And you press one key and you activate this cord.

So you activate the sweet cells throughout your oral cavity.

and they all converge into a group of sweet neurons.

In the next station, which is still outside the brain, is one of the taste ganglia.

These are the neurons that innervate your tongue and the oral cavity.

Around there.

Yeah, right here around the lymph nodes, more or less.

You got it.

And there are two main ganglia that innervate the vast majority of all taste buds in the oral cavity.

And then from there, that sweet signal goes onto the brainstem.

The brainstem is the entry of the body into the brain.

And there are different areas of the brainstem and there are different groups of neurons in the brainstem.

And there's this unique area in a unique topographically defined location

in the rostral side of the brainstem that receives all of the taste input.

A very dense area of the brain.

A very rich area of the brain, exactly.

And from there, the sweet signal goes to this other area higher up on the brainstem.