пожалуйста, возвращайтесь позднее
пожалуйста, возвращайтесь позднее
[SOUND]. So, let's now discuss the functional magnetic resonance imaging. Perhaps, this is the most popular method in neuroeconomics. It's a quite complex method. That's why I strongly recommend you to read some specialized books. Describing the details of the functional magnetic resonance imaging, for example, this book, written by Scott Huettel and colleagues. So today, I will only focus on the major aspects of the MRI, of functional MRI methods. That will help you to understand the results of your economic studies. Briefly speaking, when we will put a subject inside of the magnet, his head will be surrounded by a few different coils. The first coil, a magnet, produces a very strong magnetic field. So why do we need this strong magnetic field? Because protons of the brain will be aligned in line with the strong magnetic field. And the field is extremely strong so if you will put a metallic coil in front of this camera, it will fly inside of this camera. So next we can find a gradient coil inside of this camera. This gradient coil, produces a slight gradient in the magnetic field that will help to detect the position of the activation inside of the brain. And finally, there is a radio frequency coil that produces radio frequency magnetic field that activates protons, excitate protons during the scanning. So, let's now discuss the basic facts behind this technique. So, first of all, when you put a subject inside the fMRI scanner, the protons are aligned, in line with the strong magnetic field. Next, you apply to the brain the excitation radio frequency magnetic field. And this magnetic field activates protons. When you switch off this magnetic field, you can record the magnetic field emitted by the activated protons. This emitted magnetic field, will be slightly different depending on the tissue that surrounds the protons. So, using special algorithms, we can reconstruct the signal produced by grey and white matter, or produced by active brain regions, or less active brain regions. So here, we use a quite complicated device, and I strongly recommend you to read some literature that would explain you the details of the fMRI method. So, as you can see in this picture, MRI device is a very strange environment for the new economic studies. We use special projectors to project stimuli inside of the scanner. We use special devices to record behavioral responses of the subject. We avoid any metal inside of these devices to avoid interference with the magnetic field. But we are able to record brain activity and also record the brain structure of our subjects to exert specific behavioral tasks during the decision making process. So there are two major types of the MRI studies. The first type is called the structural MRI. So, with this method, with this protocol, we can collect a 3D atlas of the brain of our subject. But we also can use another protocol called functional MRI, with this protocol, with this sequence of pulses, we can collect the activations of different brain areas during the task. So, using the second approach, so called functional MRI, we can record the brain activity during the decision making process. So in this case, we put our subject inside of the scanner, we put sometimes for example, a small screen in front of his face. And we ask subject to make decisions inside of this camera. So we record decisions during the scanning process and we also record the brain activity during the decision making task. The result of the new economic study often looks like this picture.