Here you learn about some common neuroscience tools and techniques that I use in my research. Remember, my focus is on a small portion of human neuroscience. So this overview is by no means exhaustive!
To understand how the brain codes our behavior, we first have to investigate our behavior. To this end, participants typically perform some kind of task related to the topic of interest. This includes tasks on movement learning, visual recognition, working memory, long-term memory, cognitive learning, emotional responses, and many more.
Differences between individuals are typically related to variability in brain physiology. Analyzing this variability with any of the other methods, shown below, can explain how a specific brain region is associated with a given task.
Because we cannot always directly investigate the brain, it sometimes helps to make a computer simulation of the brain. Computational modeling comes in many forms. For example, some researchers use it to model how particular decision strategies will affect the activity of the brain. This in turn can be used in machine learning.
Another way to using computional modeling, that I use myself, is to simulate the effects of brain stimulation. By simulating how magnetic and electric fields affect the brain, we can estimate what the effect on behavior will be. It can also help us to determine where exactly we need to stimulate if we want to change performance.
Transcranial magnetic stimulation (TMS)
During TMS a short magnetic pulse is applied to the head. This induces an electric field in the brain, which alter activity in the targeted region. TMS can be used to induce activity. For example, a TMS pulse over the motor cortex can evoke a small movement. TMS can also interfere with ongoing brain activity. So, when your brain is active during a specific task, a TMS pulse can interrupt that activity.
TMS effects are typically short. However, when TMS is applied in a repeated fashion (rTMS) changes in brain activity last even after you stop stimulation. There is evidence that it promotes plastic changes in the brain, which means it is a promosing method for therapeutic applications. Read more about that in the link below.
Neurons communicate by tiny chemical changes. Ionic differences mean that a very small electric charge is induced. When a relatively large group of neurons is active, this electric charge can be recorded on the outside of the head. EEG records these tiny electric fields. When the brain is not involved in something these activities are relatively random, resulting in fluctuating lines. During specific situations groups of neurons will be active together in a rhythmic pattern. this results in rhythmic oscillations, looking like waves. All over the brain oscillations of different height and frequency can be found. They are related to specific brain functions.
When people perform a task, we can cut out the EEG at a specific event in the task. For example, we look at the EEG every time someone presses a button. These snippits of EEG are called event-related potentials and they reflect brain processes going on related to that specific event.
transcranial direct and alternating current stimulation (tDCS and tACS)
Like TMS, tDCS and tACS can stimulate the brain. However, not a magnetic field, but a small electric field is applied to the head. Compared to TMS, tDCS and tACS are less focal, meaning that they do not hit one precise spot in the brain. Rather they target a distributed area. This means they are useful when one wants to target an entire network of related brain areas.
TDCS applies a direct current, which can slightly increase or decrease activity in the targeted network. However, tACS applies oscillating currents. These current resemble the rhythmic brain waves that can be observed with EEG. So, tACS aims to directly affect those brain oscillations in a network.
functional magnetic resonance imaging (fMRI)
I myself have only worked with FMRI a handful of times. But, since this is one of the most important scanning techniques in neuroscience, I had to include it in this overview. An MRI machine can be found in each hospital and is kind of like a big magnet. This magnet alligns hydrogen molecules and so, parts of the body with more water molecules light up. This can be used to make images of the insights of our body, and thus also of our brain.
Interestingly, hydrogen physics differ between blood that is rich in oxygen and blood that is low in oxygen. That means we can scan those areas in the brain with a lot of oxygen and little oxygen. Oxygen is needed to feed neurons. So active neurons get more oxygen than non-active neurons. In this way we can find active areas in the brain with FMRI.
Each individual study is valuable and adds a little piece of the puzzle on how our brain works. But it is just that, just a small piece. After a while it is important to put together a few pieces. Even if this doesn't solve the puzzle, you got some bigger chunks. This is what a meta-analysis does. Results of multiple studies is summarized and an statistical analysis is performed over all these studies. This helps us in our way to a consensus if a certain method works, or if a certain brain region is really involved in a specific task. For example, I have used meta-analytic approaches to test whether a variety of brain stimulation methos is effective in changing human behavior.