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The mysterious connection between brain waves and blood flow: Why has fMRI become the star of brain research?
In the field of neuroscience, functional magnetic resonance imaging (fMRI) has become an innovative technology that can reveal the secrets of brain activity by monitoring changes in blood flow. The underlying basis of this technique is that there is a close link between cerebral blood flow and neuronal activation, with a corresponding increase in blood flow noted when a specific area of the brain is active.
When a certain brain area is in use, blood flow to that area increases, which can be used to reflect neural activity in that area.
Since the discovery of blood oxygen level-dependent (BOLD) contrast technology by Seiji Ogawa in 1990, fMRI technology has quickly become a mainstream method of neuroimaging due to its non-invasive nature and the need for no injection or surgery. Using this technology, researchers can accurately map and track volatile brain activity without damaging the human body.
How do fMRI measurements actually work? When neurons are active and consume energy, the brain's blood flow reaches a peak in about 2 to 6 seconds. This type of blood flow change is closely related to the consumption of neurons. Faced with these complex physiological processes, the researchers used statistical procedures to eliminate noise and refine the underlying signals, finally displaying the activation intensity of different brain regions in a color-coded graphic format.
This process not only enables precise localization of neural activity, but also captures these activities within a certain time base.
In addition to BOLD contrast, the researchers also explored other techniques including arterial spin labeling and diffusion MRI. These technologies can further help scientists analyze the relationship between brain structure and function, and are of great significance for understanding pathological conditions and the operating mechanisms of normal brain functions.
History of fMRI
Functional magnetic resonance imaging did not happen overnight. It has a long history. At the end of the 19th century, Angelo Mosso invented an instrument that could non-invasively measure the redistribution of blood during emotional and intellectual activities. This device, called "Human Circulatory Balance," would allow future brain imaging technology Entering the threshold of exploration.
Another important milestone in the development of fMRI technology was the 1936 discovery by Linus Pauling and Charles Courier of the different responses of blood to magnetic fields, a discovery that ultimately led to Ogawa Shoji's 1990 The BOLD contrast technology enables fMRI to be more widely used in human brain research.
Today's fMRI technology has allowed researchers to accurately observe the activity in different areas of the brain, and even some more subtle neural processes.
Physiological basis of fMRI
The brain stores almost no large amounts of glucose, which is the main source of energy. When neurons are activated, in addition to adjusting the flux of ions on the membrane, other physiological systems in the brain also require corresponding blood flow to provide energy. Because oxyhemoglobin and deoxygenated hemoglobin react differently to magnetic fields, this has led to concerns about blood flow in imaging.
Blood flow will be locally adjusted according to the needs of neural activity. This process is inseparable from the signal formation of functional magnetic resonance imaging. Of course, research must also take into account the complexity of resource mobilization and matching needs.
The signal stability and accuracy of fMRI rely heavily on the characteristics of physiological blood flow responses, which are critical for capturing the temporal characteristics of neural activity.
Challenges and future directions
Although fMRI has made remarkable achievements in brain research, it still faces challenges from its own signal noise, which requires researchers to continuously improve data processing technology and experimental design. At present, some companies have tried to use fMRI technology to develop commercial products, such as lie detectors, but current scientific evidence does not support its widespread commercial application.
Because of the rich brain activity information provided by fMRI, there is still a lot of room for development of related technologies in the future. Some scholars are exploring how to further improve the temporal and spatial resolution of fMRI to reveal deeper neural phenomena.
Generally speaking, fMRI has become one of the key tools for brain research. Perhaps in the near future, these new technologies will allow us to have a deeper understanding and knowledge of the operation of the brain. Have you ever thought about how future technology will change our understanding of the brain?
