Inferring Behavior from Neuronal Networks

Professor William Kristan describes techniques for studying connectivity patterns in neurons and how they affect motor behavior.

So, how we find out the function of circuits is to start with the behavior and look back toward the nervous system. So, see what the behavior is and then find out what the motor neurons do - those are the ones that make the muscles contract. So, if we know the pattern of activity of the muscles, we know which leg, which arm, which part of the body is moving, we know which muscles are moving, therefore we know what the motor neurons are doing. So that tells us a lot about what the motor side of the nervous system is doing. Then we look one step back to see what cells are connected to those. We now, for several behaviors, for something called "local bending" (if you poke an animal in one place, it bends in that direction) for shortening, and for swimming, we know most of the cells that are involved in it and how they connect to one another. So, the structure of the nervous system told us where to look from animal to animal, but what we started with was the behavior with the function per se, and looked to find out the connectivity that actually produced that.