Do You Know How to Measure a Brain's Behavior?

Scientists have been able to sample from, say, 100,000 routinely now at the same time for multiple brain areas. What we've discovered is that if you have an animal doing a task, relatively simple task in terms of discrimination or judging, making a decision about whether to go right or left. And they learn how to do that. But under all of the cases that we have studied so far, it looks as if the part of the space of all the activities and all the neurons that are actually carrying the information that you need is a very low dimensional subspace.