4-1 Cognitive Neuropsychology

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Research Methods in Cognitive Neuroscience

How Do We Study the Brain?

The study of the brain has a very long history. Even as early as the sixth century, scientists were aware that there was a relationship between the brain and functions such as movement, sensation, and cognition. Over the centuries, researchers gained a better understanding of the critical role of the brain and it was eventually accepted that the brain, and not the heart, is the control center for the body (Gross, 2009).

Scientists continue to study brain structure and function. Fortunately, recent technological advances enable scientists to obtain high-resolution 2D and 3D images of the brain structures in living humans. Researchers can also see the parts of the brain that are active when people perform various tasks. Advances in technology have led to science’s current ability to examine brain structure and function in humans using noninvasive techniques. These techniques have dramatically affected research in cognitive neuroscience and medical practice. Doctors can now view the brains in vivo of patients with damage or neurological disorders, creating new treatment avenues (Toi et al., 2022).

Many methods are used to study the brain. However, this module will focus on neuroimaging techniques used to examine the living brain in humans. Some commonly used techniques include CT scans, MRI, fMRI, DTI, PET, SPECT, EEG, MEG, and NIRS. Each of these techniques is explained briefly below:

• CT (computerized tomography): CT involves a scanning beam of multiple X-rays from different directions to produce 2D images of cross-sections of the brain or body. Head CT is used clinically to identify prominent brain abnormalities, such as fractures, tumors, or pooled blood. This type of scan is most frequently used in emergency departments or soon after head trauma.
• MRI (magnetic resonance imaging): MRI involves the use of magnetic fields and radio waves that can produce very high-quality brain images. Researchers and clinicians frequently use this technique to see the brain’s structure. A brain MRI helps examine more subtle damage to the actual brain tissue because it has better resolution than a CT. For example, a brain MRI is useful in examining tissue softening or stroke. Thus, an MRI is used clinically in the post-acute stages of recovery.
• fMRI (functional magnetic resonance imaging): fMRI also uses magnetic fields and radio waves, but this method allows scientists to see brain function rather than just structure. This technique examines brain activity when someone is doing a task, such as reading a book, solving a math problem, or listening to music. fMRI allows one to localize a function within the brain. It can examine changes in function over time.
• DTI (diffusion tensor imaging): DTI uses a modified MRI scanner and near-infrared light to reveal bundles of neurons. DTI does not show actual axons or identify specific bundles accurately. Due to the poor resolution of DTI with current technology, it identifies estimates and generalizations of functional activity.
• PET (positron emission tomography): PET scans create images based on the movement of radioactive material that is injected into the body. A computer processes the movement to produce 2D or 3D images.
• SPECT (single-photon emission computed tomography): Like PET, SPECT relies on an injected radioactive substance and nuclear imaging to observe brain functioning. SPECT is lower quality than PET and currently not often recommended for clinical use.
• EEG (electroencephalography): EEG uses electrodes placed on the scalp to record electrical activity. This technique is used in many research and clinical settings. EEG is most useful in identifying the location of seizures. The technique is common in both research and clinical settings.
• MEG (magnetoencephalography): MEG records small magnetic fields produced by brain functioning and is currently used in research settings for more accurate localization of brain activity.
• NIRS (near-infrared spectroscopy): NIRS uses the near-infrared region of the spectrum and is sometimes used as an alternative to fMRI. It allows one to localize function to some extent. However, it does not do as well as fMRI since it only scans cortical tissue. Still, it is portable, much less expensive, and can be used with children (who may move too much to get information from an fMRI). Its use is growing in pediatric care.

All these techniques are useful and have a place in research, hospitals, and other clinical settings. Each has advantages and disadvantages. The most appropriate choice depends on the situation.

Imaging techniques may also have high value, even with very young children. For example, routine MRI in at-risk neonates may help alert medical professionals to serious intracranial conditions or predict cognitive outcomes (Badke D’Andrea et al., 2022). However, first consider several issues when using imaging techniques with children. Many techniques (for example, closed MRI) likely will produce a claustrophobic response. Claustrophobic responses may be especially difficult to control in children. Also, many imaging techniques rely on the patient to remain still during the procedure, which can be especially difficult with younger patients. Moreover, research, in general, is more difficult when targeting child samples. Thus, progress can be slow in solving such issues.

References

Badke D’Andrea, C., Kenley, J. K., Montez, D. F., Mirro, A. E., Miller, R. L., Earl, E. A., Koller, J. M., Sung, S., Yacoub, E., Elison, J. T., Fair, D. A., Dosenbach, N. U. F., Rogers, C. E., Smyser, C. D., & Greene, D. J. (2022). Real-time motion monitoring improves functional MRI data quality in infants. Developmental Cognitive Neuroscience, 55. https://doi-org.ezproxy.snhu.edu/10.1016/j.dcn.2022.101116

Gross, C. G. (2009). A hole in the head: More tales in the history of neuroscience. MIT Press.

Toi, P. T., Jang, H. J., Min, K., Kim, S.-P., Lee, S.-K., Lee, J., Kwag, J., & Park, J.-Y. (2022). In vivo direct imaging of neuronal activity at high temporospatial resolution. Science, 378 (6616), 160. https://doi-org.ezproxy.snhu.edu/10.1126/science.abh4340