September 20, 2007 -- Neurons for Good and Bad Surprises

Say you are walking in the forest. Birds are chirping. Sun is shining. And you come around a corner and bam, you're face to face with a grizzly. And you freeze!

Now let’s say you came around that same corner but this time you run into your old pal Joe.

Both events are equally surprising, and our amygdala, the emotional part of the brain, is activated. But how does the amygdala process what makes us recoil from the bear, but go to hug Joe?
Researchers recently reported in the journal Neuron, that there are two circuits at work.
 
They measured the firing of nearly 300 cells in five monkeys. The monkeys either received an unexpected sip of water (nice surprise) or a puff of air in their face (bad surprise).
 
Scientists found that in the amygdala, there are a group of neurons that specifically react to surprise. And then there are different neurons that react to only good or only bad surprises.
 
As for the next step in brain mapping: scientists want to see if there are dedicated neurons for different kinds of nice surprises, like for money surprises, chocolate cake surprises, or even “old pal Joe” surprises.