A Review of Two Brain Research Tools

by Andres Tuccillo, Kenyon College, '22  

This is a listing of two commonly used neurological research tools (the fMRI and EEG). As well as a common explanation of their functions, the numerous strengths and weaknesses of each research tool will be explained below. 

One very popular and useful research tools is the fMRI (or functional magnetic resonance imaging). This technique is similar to the MRI but it allows researchers to see the brain, for lack of better terms, “in motion.” Basically, researchers are able to see which regions of the brain are activated when certain stimuli are encountered or when a certain cognitive operation is needed. In research specifically angled toward adolescence, fMRI has been useful to see how brain functions differ between age groups. Furthermore, fMRIs are able to take these images because of the simple fact that when a particular part of the brain is used, blood flow to that region aa well as blood oxygenation increases. This is commonly known as hemodynamics. Oxygenated red blood cells carries oxygen to the brain, displacing deoxygenated red blood cells. Oxygen is carried in red blood cells by the molecule hemoglobin. Deoxygenated hemoglobin (dHb) is more magnetic than oxygenated hemoglobin (Hb). The different magnetic properties of oxygenated and deoxygenated blood can be visualized by the fMRI. There are many strengths attributed to the fMRI. First off, it is a noninvasive procedure. Subjects are not poked and prodded; there are no outside elements invading their body. The fMRI is able to examine living, healthy, and developing brains by taking detailed images. However, there are limitations. These include that fact that subjects need to be motionless for the procedure, and this is not guaranteed, especially with adolescence. Also, a subject may be claustrophobic, so the tight space of the fMRI machine would be terrifying. Lastly, as of right now, there is no consensus as to how exactly analyze fMRI data. 

Another brain research tool is the electroencephalogram (EEG). An EEG measures the electrical impulses passed between neurons. To do this, the EEG test uses electrodes (consisting of small metal discs with thin wires) placed on the scalp. These electrodes collect the electrical information from the firing neurons, amplify them and it is this information that appears on a computer screen. Furthermore, neurons communicate through five different waveforms: alpha, beta, gamma, theta, and delta waves. Each different waveform signals a different cognitive process. This is how EEGs are able to tell what a person is thinking/doing and which regions are activated. Alpha waves signal that someone is waking up from sleep and beginning cognitive function; baeta waves signal anxiety, depression, or the use of sedatives; gamma waves signal peak focus and consciousness; theta waves are most common in children and young adults; and delta waves occur in young children during sleep. One major strength of the EEG is that it is a vert safe procedure. The electrodes do not produce any sensation when used, they merely collect information. Also, the EEG is less sensitive to participants moving than the MRI. Finally, the EEG records information in real time. This gives an extremely accurate image of the region of the brain that is being studied. The main limitation is that it does not provide a detailed image of the brain. Its spatial resolution is poor at best because only impulses from the surface of the brain are acquired.

Image collected from a fMRI:
 
fMRI_brain-scan.jpg

Digram of an EEG: 

ZrmxJRu.jpg

Reference List:
Galván, A. (2017). The Neuroscience of Adolescence. New York, NY: Cambridge University Press.