what happens when you see one of these so-called pictures of the brain you've all seen these things they have red and blue and yellow and so on there's no red 00:01:21 and blue and yellow in the brain what happens is this if the pictures are not pictures of the brain they're pictures of gia the ratio of oxygenated to 00:01:35 deoxygenated blood in certain places and when neurons fire they need to be getting some oxygen back in there too so they can fire again and it turns out that they have different magnetic 00:01:49 properties if their oxygen if the blood is oxygenated or not and what you see actually is a bunch of pixels and each little pixel is actually 3 millimeters 00:02:03 by 3 millimeters by 3 millimeters 3 millimeters cubed and it goes over anywhere between one second and several seconds now if you ask how many neurons are in there the answer is about 125 00:02:17 million per pixel each neuron is connected to between a thousand and 10,000 other neurons so there are tens of billions of connections lots of circuitry in that one little 00:02:30 pixel and that picture doesn't show you what's going on in that circuitry very important you know we cannot see that we can say hey something is happening there