[SOUND] [MUSIC] So today we will discuss six major approaches to investigate the activity of the brain. So why do we need so many methods to investigate the neural methods of decision making? Simply because there is no one ideal method. So all methods can be characterized by the temporal and spatial resolution. Temporal resolution means how well in time we can differentiate different stages of decision making process. Spatial resolution means how well in space we can differentiate different neuronal populations involved into the decision making process. Unfortunately there is no one ideal neuroscientific method that would have perfect temporal and spatial resolution. We have to combine different methods to understand the dynamic of the neural mechanisms of decision making and the localization of those mechanisms inside the brain. So let's first discuss the facts of lesions on our decisions. So, lesions can trigger some changes in our behavior and also in, in the way we make our decisions. So, neuropsychology investigates the effects of lesions on our behavior. There are really famous cases, illustrating how the trauma in the specific brain area can lead to specific changes in our decision making. So, for example, we happen to know the famous case of Phineas Gage. So, he lost a portion of his prefrontal cortex. So during an accident, a huge iron rod penetrated his brain, and removed the part of his frontal cortex. So nowadays, we can reconstruct the place that was destroyed in the brain by this iron rod. So using the modern reconstruction technique, we can actually reconstruct that, this accident and here we clearly see that the portion of the medial frontal cortex was removed by this accident. Surprisingly, he survived. But his behavior, his decision-making process changed substantially. He became a very emotionally unstable person. He got a lot of problems in social interactions. He lost his job. So, the way he made social decisions, the way he behaved, changed dramatically. So, for example, Antonio Damasio was so interested in this case, that he collected patients with similar traumas, with similar lesions. So, this picture indicates the main focus of these traumas. So, in most of the cases, the orbitofrontal cortex or the medial portion, medial ventro prefrontal cortex was damaged. And as we will see during the course, the damage of this region leads to very important changes in decision making process. So, we know now that this portion of the orbitofrontal cortex is really critical for emotional learning, for optimal decision making, for evaluation of options for the comparison of options. So, how do we normally study patients with specific traumas? So we asked these patients to perform a task and we compared behavioral results with a control group. So we simply collect behavioral information and compare the results of two groups. Results of patients and results of the normal subjects. So in this graph, you see below an example that will be discussed in this course. So you see that normal people, during the test, quite quickly differentiate optimal and su, suboptimal decisions. But patients with the lesions in the ventromedial prefrontal cortex, they do not differentiate optimal and suboptimal decisions in this particular task. They make a lot of mistakes. We will discuss the results and very influential results during the course. So, lesions in specific brain regions can lead to very specific changes in our decision-making. Overall, lesion studies bring very interesting, important insights for neuro-economics. But, as were not so many cases when we can find patients with exactly the same lesions. Normally these lesions are not very focal, so quite often large portions of the brain are damaged. Sometimes it's difficult to interpret the outcome of the lesion. Imagine that your iPod for example lost the battery. So iPod will stop to produce sounds, but it doesn't mean that battery is directly involved into the sound production. In the same way, the lesion in the brain region can lead to sudden problem in decision-making process. But it doesn't automatically mean that this brain region is directly involved into the decision-making process. But anyway, these studies, they show causal relationship between the activity of certain regions and decision-making process. And these studies give us very interesting insights. So another way to investigate the activity of certain brain regions, is the stimulation of this brain region. So there is a long history of studies that investigated the facts of the stimulation of the brain. So for a long time, we know that it would stimulate certain brain regions, especially in the hypothalamus. We can trigger aggressive behavior. So, animal behaves aggressively if you stimulate the very specific region of the hypothalamus. On the other hand, we know that we, you can induce fear by the electrical stimulation of certain brain areas. So for a long time, we know that we can actually evoke different behavioral patterns by the stimulation of the very specific brain regions. So if you would be really interested in the history, a very rich history of this stimulation studies, you can read books of Jose Delgado, who conducted various impressive studies. For example, in one study, he used remote control to stimulate the brain of the bull. So, as you see here, this bull attacks, but the remote control allowed the scientist to stop this bull using the electrical stimulation of the specific brain area. So already many years ago, we could modulate behavior of animals, and we can actually affect some decisions of animals. So during this course, we will get these examples, how electrical stimulation modulates decisions. So, we will discuss, for example, where is the simple decision making task, so called perceptual decisions. So in this case, animal and monkey has to switch gaze left or right. A monkey has to switch the gaze in the same direction as the majority of dots on the screen moves. So if all, or most of the dots are moving right, monkey has to switch gaze right. If majority of dots are moving left, monkey has to switch gaze left. So we can change the proportion of dots moving right and left and change the difficulty of the task. I will not go into details of this task now. We will discuss it in the next lecture. But, I will just show you that the full plot, the proportional specific choices made by monkey. We can change choices by the electrical stimulation of this neurons that are involved into the decision-making process. So as you see here, as the red curve indicates that after the stimulation of the specific neurons, we change choices of the monkey. So we shift this plot left. We will discuss this impressive studies next week. But it shows us that we can stimulate specific neurons in the brain and we can change decisions. Of course it's very interesting methods, but it unfortunately, it is invasive so in order to put an electrode inside of the brain, you have to damage some tissues. This is a good method to study rapid changes in decision making induced by the electrical stimulation. Unfortunately, the stimulation not very focal. Because when you electrically stimulate brain tissue, you normally stimulate a large portion of the brain. But I think these stimulation studies, they also bring us very interesting, very impressive results. There is a way to stimulate the human brain and without any damage to the brain. This method is called Transcranial Magnetic Stimulation. You see on this screen the coil. This coil consist of metallic wires, and if you apply a very strong current, this coil produces a very focused magnetic field. So by rapidly changing magnetic field, we can induce inside of the brain some rapidly changing electrical currents, that will disturb activity of neurons. So by single magnetic pulse, we can temporarily, quickly disturb activity of certain neuronal population while there're repeated magnetic pulses. We can shut down or inhibit activity of this region for 10, 20 minutes. So we will discuss the results of TMS studies. We will see that by transcranial magnetic stimulation, we can change our decisions. So, as you see on this graph, this, TMS coil induces magnetic field. Magnetic field penetrates our brain and induce some local currents in the brain that disturb, activity of neural population. So, on this scheme, this process is illustrated and explained in details. So you see that strong current in there will induce this magnetic field. Magnetic field penetrates the skull and induces current flow inside those brains that temporally inhibits the activity of the neuron in yours. So, in this video you can see an example of the TMS study. This experiment was conducted in Helsinki. And this person has to name objects presented on the screen. And by trans-cranial magnetic stimulation, we can suppress the performance of this task. So this person will not be able to name these objects. This effect is called speech arrest. So as you see, this person names this objects, but when magnetic field is applied to the specific speech related area, this person cannot speak. He cannot tell anything. So his speech is blocked by magnetic field. So in your economics, we use the same approach. So we temporarily block some aspects of the decision making. So this graph represents the key aspects of transcranial magnetic stimulation method. So, you put the coil, TMS coil, near the head, near the brain and using special algorithms, or special algorithms helps you to navigate magnetic field inside of the brain. So we can select the [UNKNOWN] in the brain and apply magnetic field to this brain area and temporarily inhibit this brain area. And, as a result, you can investigate how does this magnetic stimulation change decision making process? So, in this example, you see, the results of the very famous study showing the acceptance rates of unfair financial offers. So, as we see here, the transcranial magnetic stimulation of the right dorsolateral prefrontal cortex, leads to the higher acceptance rate of the unfair financial offers. Relative to the control, relative to the stimulation of the left dorsolateral prefrontal cortex, and relative to the sham stimulation. So, to the condition when there is no trans-cranial magnetic stimulation is applied. So, by stimulation of the certain brain region, of the right dorsolateral prefrontal cortex, we can change our reaction to the unfair financial offers. We start to agree with unfair financial offers. So by trans-cranial magnetic stimulation, we can change our decisions. We will discuss in details this kind of studies during the course. TMS is really interesting. New methods that is used in, in neural economics. So it can induce very transient effects so we can quickly change decisions by single pulses. We can induce more long lasting changes by repetitive transcranial magnetic stimulation. We can inhibit activity of certain region for 20, 30 minutes. So, this method show us also the causal relationship between the activity of the brain region and the aspect of the decision making that is changed by the transcranial magnetic stimulation. Unfortunately it is quite difficult to stimulate deep brain structures. You need too strong of a magnetic field to do it. But, most of the TMS studies focus on the cortex. On the surface of our cortex. So, there are some disadvantages of this method. Of course, this method produces some noise, acoustic noise, and also can involve some twitches of the muscles. But I think this is one of the most promising methods of the modern neuroeconomics. [SOUND] [MUSIC]
