In a recently in the journal "Nature Neuroscience" published study found a research team to study leader Thomas Jentsch, that genetic hearing loss also affects the sense of touch. The reason for this is a gene that has been identified only in connection with hearing loss. Well, it was discovered that this gene also affects the previously little-explored sense of touch. According to the study of human sense of touch work with genetically caused hearing loss is more sensitive than that of healthy people-related.
Genetic deafness
In the study of Spanish and Dutch families were studied in which there is a genetic deafness type DFNA2. In this form of deafness, the function of some hair cells in the ear is disrupted by mutation.
To listen to swing the tiny hairs in the ear to the rhythm of the sound waves. This potassium ions flow into the hair cells, and it will transmit a nerve signal to the brain. The potassium ions then flowing through a channel in the cell membrane again. For the hearing impaired, this channel is broken by a mutation. The channel consists of a protein molecule called KCNQ4. By overloading it comes to the death of sensory cells.
Now, researchers found that this mutation also affects the sense of touch. Study leader Thomas Jentsch from the Leibniz Institute for Molecular Pharmacology (FMP) reported: "We have found that KCNQ4 appears not only in the ear, but also in some sensory cells of the skin." Jentsch continues: "This has brought us to the idea that the mutation could also affect the sense of touch. This we were able to show a close collaboration with the laboratory of Gary Lewin, a company specializing in touch colleagues from the MDC, in fact. "
How does the sense of touch?
Without consciously perceive the sense of touch gives us every moment of vital information about our environment. Let us for something we know through the contact, immediately, whether it's hot, cold, smooth or rough. Our surface perception works on receptors in the skin, which are divided into pain-, mechano-and thermoreceptors. So we can perceive pain, vibration, touch, temperature and pressure. As the sense of touch is so far largely unexplored, one can only speculate about the exact mechanisms. Is known, however, that available for the various tactile stimuli are sensory cells in the skin. By deformation of these cells generates an electrical nerve signal that is relayed to the brain.
To find the combination of genetically caused deafness and altered sense of touch on the trail, the researchers first developed a model study using mice showed the same mutation of the potassium channel, such as people with this form of deafness. The touch receptors in the skin die due to defective channel does not like the ear. The mutant mice, however, showed that they reacted with a different electrical signal to mechanical stimuli. The touch receptors responded significantly more sensitive to vibration stimuli in the low frequency range. The researchers concluded that the potassium channel appears to act as a kind of shock. If the channel is formed normally only be fast vibration frequencies and higher perceived. If the channel is damaged, the skin becomes more sensitive.
In the investigation of families, the researchers came to the same result. The children who had mutations in the potassium channel could feel vibrations significantly slower than their healthy siblings. Gary Lewin and Thomas Jentsch summarized: "The skin has several different types of mechanoreceptors that respond to different stimulus qualities, especially in different frequency ranges. The interaction of different classes of receptors is important for the sense of touch. Although we studied a total of receptors are more sensitive due to loss of the potassium channel, may outweigh the disadvantage of the 'wrong' mood 'to other frequencies.
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