Neuroimaging explores the intricate structure and function of the central nervous system through cutting-edge quantitative techniques. It can be traced back to the 19th century, when Angelo Mosso, a pioneering physiologist, introduced the idea of human circulation balance. Mosso hypothesized that the brain requires increased blood supply during periods of heightened cognitive activity—a revolutionary idea that laid the groundwork for modern neuroimaging techniques.
Today, researchers employ a variety of brain imaging modalities, such as Functional Magnetic Resonance Imaging (fMRI). These methods allow us to visualize and measure brain activity by tracking changes in local blood flow, oxygenation levels, or electrical signals. In this article, we will delve into how current neuroimaging techniques work and the ethical considerations of neuroimaging.
Current Neuroimaging techniques
Positron Emission Tomography (PET)
Positron Emission Tomography (PET) is an advanced imaging technique that enables the assessment of tissues and organs' functionality. The PET process utilises radioactive tracers that tightly bind to glucose molecules. These molecules then travel through the bloodstream and accumulate in areas requiring high glucose levels. When these tracers collect in regions like the brain, they create visible bright spots that sensors within the PET scanner can detect.
The spots are captured and transformed into video images of the brain, allowing medical professionals to analyze and interpret the visual representation of brain activity. Since neurons utilize glucose for energy, PET is highly effective in depicting various levels of brain activity, making it an essential tool for identifying potential abnormalities or areas of interest within the central nervous system.
The above picture showcases an image from a PET scan of a brain. Warmer colors signal higher neuron activity, while cooler colors signal lower neuron activity.
Positron Emission Tomography (PET) offers a key advantage over other neuroimaging techniques by detecting tissue changes earlier. This early detection is crucial for diagnosing and treating various medical conditions. However, PET scans expose patients to a small amount of radiation, which poses a minor cancer risk.
Electroencephalography (EEG)
Electroencephalography (EEG) records the brain's electrical activity through electrodes placed on the scalp using specialized glue or within a unique cap. These electrodes capture the electrical signals produced by the action potential of neurons and transmit this information to a recording device. The recorded brain activity reveals distinct patterns, which can be analyzed to provide insights into various cognitive processes and potential abnormalities within the brain.
One such example of a wave pattern would be gamma waves, which are associated with brain activity when we are actively learning and have a heightened perception.
EEG is advantageous as it improves patients’ comfort by allowing patients more freedom of movement during the imaging process. However, its spatial resolution poses a drawback. Since electrodes measure electrical activity at the brain's surface, it is challenging to determine whether the signals originated in the cortex or deeper brain regions. This can impact the accuracy of pinpointing the source of brain activity and the interpretation of results.
Functional Magnetic Resonance Imaging (fMRI)
Functional Magnetic Resonance Imaging (fMRI) is a powerful neuroimaging technique that generates detailed three-dimensional brain and body anatomical images.
The fMRI process involves a scanner that utilizes magnetic fields and radio waves to manipulate the magnetic position of hydrogen protons in the body.
As these protons rotate and release energy, a powerful antenna detects these changes and transmits the information to a computer. The computer then analyses this data, performing complex mathematical calculations to create clear, cross-sectional black-and-white images of the body's internal structures. These images can be further processed and transformed into three-dimensional representations of the scanned region, as depicted in the image provided.
fMRI provides better visualization of soft tissues like muscle and fat compared to other imaging techniques. However, its requirement that patients remain within a metal tube-like scanner throughout the potentially lengthy process can be impractical for ill patients or those unable to tolerate prolonged confinement.
Brain imaging uses
These are some uses for brain imaging.
Healthcare: Brain imaging aids in diagnosing neurological disorders, assessing brain injuries, and planning treatments for various conditions.
Criminal Law: Brain imaging is increasingly used in criminal law, providing potential evidence for insanity pleas, detecting lies, or assessing a defendant's mental state.
As brain imaging technologies advance, some ethical concerns surround the use of brain imaging technologies.
Privacy concerns: Brain imaging data can reveal sensitive information about an individual's thoughts, emotions, and behavior.
Informed consent: Obtaining informed consent from individuals undergoing brain imaging is essential for respecting autonomy and privacy. Participants must understand the risks, benefits, and potential consequences of sharing their brain data.
Commercialisation of scan: As these techniques become more widespread, ensuring equitable access to these tools and preventing the exploitation of personal data will be critical.
Achieving a balance between scientific progress and personal privacy requires thoughtful consideration and collaboration among researchers, policymakers, and the public. Establishing responsible data collection and usage guidelines, promoting education and transparency, and considering ethical implications will contribute to responsible innovation and respect for individual rights.
Reference list
Benderev, C. (2020). NPR Choice page. [online] Npr.org. Available at: https://www.npr.org/2014/08/17/340906546/the-machine-that-tried-to-scan-the-brain-in-1882.
Bosquez, T. (2022). Neuroimaging: Three important brain imaging techniques. [online] ScIU. Available at: https://blogs.iu.edu/sciu/2022/02/05/three-brain-imaging-techniques/.
byjus.com. (n.d.). What are some drawbacks of MRI Magnetic Resonance Imaging? [online] Available at: https://byjus.com/question-answer/what-are-some-drawbacks-of-mri-magnetic-resonance-imaging/.
Farnsworth, B. (2022). EEG vs. MRI vs. fMRI - What are the Differences? - iMotions. [online] Imotions. Available at: https://imotions.com/blog/learning/research-fundamentals/eeg-vs-mri-vs-fmri-differences/#:~:text=A%20drawback%20for%20EEG%20is.
Smith, K. (2024). How to Choose Between a PET Scan vs. MRI - Ezra. [online] ezra.com. Available at: https://ezra.com/blog/pet-scan-vs-mri#:~:text=A%20PET%20scan%20exposes%20the [Accessed 15 Apr. 2024].
UC San Diego (2019). What is FMRI? - center for functional MRI - UC san diego. [online] Ucsd.edu. Available at: http://fmri.ucsd.edu/Research/whatisfmri.html.
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