Finding New Brain Area that Processes Warmth Sense

 

KRISS has revealed the secret to the pure warmth sensory perception process by using magnetoencephalography

 

The research team led by Dr. Kiwoong Kim, a principal research scientist from Ultra-low Magnetic Field Team of KRISS, has found for the first time in the world that the primary somatosensory area (S1)* of the cortex processes pure warmth sense, by using an ultra-high sensitive magnetoencephalograph.

 

? Magnetoencephalography is a technique to measure magnetic fields fromthe neuroelectric activity in a brain. The magnetic field is transparent in all the human organs, which makes it possible to accurately measure electrical activities of brain nerves without signal distortion in electroencephalography.

 

* Somatosensory Area: a part of the cerebral cortex in charge of body sensory perception, such as the sense of touch and the sense of pain. The area is divided into primary (S1) and secondary (S2) areas.

Among the five senses of the human body, the sense of touch, which reacts to external stimulus, plays a critical role in perceiving pain. Therefore, measuring tactile nerves corresponds with diagnosing pain disorder. Among tactile nerves, warmth nerves that have relatively low cell density are the ones where damage is likely to be detected at the earliest possible stage. Therefore, it is possible to detect nerve damage and to diagnose disease at an earlier stage merely by checking whether the sense of warmth is felt.

If the density of nerve cells is low, once certain cells are damaged, there are few surrounding cells that can work on behalf of the damaged cells. That is, warmth nerves having relatively low cell density become incapable of delivering stimulation to the brain even with subtle nerve damage.

 

Dr. Kiwoong Kim measured the brain reaction to a pure warmth stimulus that does not accompany pain appreciation by using a magnetoencephalography device developed based on SQUID (Superconducting Quantum Interference Device). As a result, he proved for the first time in the world that the primary somatosensory area (S1) of the cortex reacts to pure warmth stimulus.

 

The research team has developed a laser stimulation device to apply only the warmth stimulus to the human body without direct contact with it. The wavelength of the laser light has been specifically chosen to minimize the amount of the light absorbed on the skin surface and to apply the stimulus deep enough to reach the warmth nerves.

 

The secondary somatosensory area of the cortex has been the only area that has been proven to process pure warmth sense. fMRI indirectly indicated that S1 might be capable of processing the sense, but there was controversy over the possibility as the equipment failed to measure electrical activities of nerves which otherwise could prove the possible capability of S1.

 

Magnetoencephalography can analyze the exact location of the source of neuro-electrical currents that generates magnetic fields in the brain when warmth stimulus is applied. It makes it possible to find new areas that react to the stimulus, which could not be detected by other instruments, such as electroencephalogram or fMRI.

 

Currently, questionnaires that ask patients to check out the level of pain on a scale of 1 to 10 have been used, which is very subjective. Research that uses magnetoencephalography is all the more meaningful given that the findings of the research are obtained by measuring the sensory process of the human body with an objective index based on a neurophysiological cerebral reaction, not with subjective questionnaires.

 

KRISS has already developed a magnetoencephalograph at its finest for the human body by only using homegrown technologies, and was successful in technology transfer in 2016 as its excellence has been recognized.

In addition, KRISS has published a number of papers related to brain science and brain disorder through joint research using the magnetoencephalograph with renowned research institutions and hospitals in Korea. In the present study, the research institute succeeded in brain science research without cooperation with other external organizations, proving that the research competence of KRISS has reached the global level in brain science as well as in the development of measuring instruments.

 

The findings of this research were published as a cover issue article of May issue of this year in one of the best brain science journals, Human Brain Mapping.

 

 

 

1. Pure warmth Sense

warmth sense in neurophysiology is divided into two types of senses: one that accompanies pain appreciation, and another that does not. It had been thought that the primary somatosensory area (S1) can process only the warmth sense that accompanies pain appreciation (hotness, sharp coldness). However, the present research has proven that the area can process even pure warmth senses like mild warmness.

 

2. SQUID (Superconducting QUantum Interference Device)

SQUID is a precise measurement device using superconducting phenomena. The device is a sensor with ultra-high sensitivity that can reach the quantum mechanical measurement limit. The magnetic field sensor using SQUID is capable of measuring even little change in the magnetic field weak enough to be a ten billionth of the earth magnetic field.

 

3. MEG (MagnetoEncephaloGraph)

The brain consists of a number of brain nerve cells (neurons). As the nerve cells exchange electricity with one another, brain functional activity takes place. Once the electrical current flows across the nerve cells, magnetic fields are generated, forming magnetic field distribution. The technology to detect the distribution by using the ultra-high sensitive magnetic sensor, SQUID, is the magnetoencephalography.

SQUID-based magnetoencephalography measurement technology is a non-contact, non-invasive diagnostic technology with excellent time- and spatial-resolutions. The next-generation medical diagnostic technology allows the collection of 3-dimensional information about the areas where neural activities of the brain occur, which sets the technology apart from the existing diagnostic technologies for brain function.

 

 

 

▲ Magnetic fields are generated from the source of neuro-electrical currents in the brain when warmth stimulus is applied to skin. The research team has analyzed the precise point where magnetic fields are generated and proven that the primary somatosensory area (S1) also processes pure warmth sense, which has been known to be processed only by S2 (secondary somatosensory area).

 

 

▲ Dr. Kiwoong Kim, and his research team member are analyzing the results of magnetoencephalography measurement of pure warmth stimulus.