Auditory memory causes ” noise in the head ,” according to a study. Once again, the brain is responsible. Researchers specializing in the auditory system have been able to determine the underlying cause of tinnitus. According to the study, these annoying “noises in the head” occur due to the existence of an auditory memory formed in our brain. Therefore, people with congenital deafness do not suffer from “tinnitus” because they have never perceived sounds that would allow them to generate such a memory.
We’ve probably all heard a noise, a ringing , or a buzzing in our ears at some point in our lives, even though there’s no external source. Suddenly, it goes away.
However, a percentage of the population (between 10 and 15%) hears this annoying noise continuously and never stops. For them, there is no silence, and the noise significantly impacts their quality of life.
These sounds are called tinnitus or tinnitus. It’s a little-known condition and a serious health problem that we perhaps don’t give the attention it deserves. Tinnitus can cause sleep disturbances, anxiety, and even depression.
During the day, internal noises are less noticeable, while external noises blur them. However, the drama comes when it gets dark. The silence intensifies and internal noise becomes more noticeable, preventing the patient from falling asleep. They become nervous, suffer from insomnia, and end up entering a dynamic that affects other aspects of their health.
Well, that’s what prompted researchers at the University of Calgary (Canada) and Hannover Medical School (Germany) to delve deeper into the topic. The scientists were able to determine the reason for this ringing in the ears, as they published in Hearing Research.
To this end, they examined evidence for the development of tonotopic maps (the distribution of the frequencies of sounds perceived in the ear and in the brain) in animals. They found that the onset of tinnitus requires a consolidated and used somatotopic map, which leads to the formation of the corresponding somatic memory. The lack of this experience explains the absence of tinnitus in bilateral and unilateral congenital deafness.
According to researchers, to suffer from tinnitus, you need to have auditory memory before hearing loss. If a person is deaf, they won’t suffer from tinnitus.
The brain is responsible
Tinnitus, whistling, “ noises in the head ,” buzzing, are some of the names given to the perception of sounds that we hear for 24 hours in our head, in the absence of physical sound sources inside or outside the body.
Tinnitus isn’t a disease in itself. It’s considered a disorder that indicates something is wrong with the auditory system. Well, neuroscience research has begun to reveal that tinnitus is generated by the brain itself. So, although you hear these sounds in your ear, the problem lies in the networks of brain cells or neural circuits. In short, in the brain.
The onset of tinnitus is mainly attributed to hearing loss and stress (emotional and psychosocial), as well as various infectious diseases (mumps, meningitis, among others) or even the intake of certain medications, among others.
These disorders can also appear in people who are completely deaf. It’s somewhat paradoxical. If you can’t hear external sounds, how can you hear these internal noises? Furthermore, people with congenital deafness don’t suffer from tinnitus, yet their perception of sound is the same. So what’s the explanation for this? Why do some people suffer from it and others don’t?
The reason
Eggermont and Kral, the authors of this study, determined that the existence of auditory memory (somatic memory) is what causes tinnitus. The memories that constitute memory are formed based on initial brain projections of certain sounds and their active maintenance throughout development . This memory collects different frequencies of sounds we perceive externally, forming the so-called tonotopic map.
Therefore, people who have lost their hearing at some point in their lives have been able to develop such maps up until the moment of their loss. Faced with this new condition of hearing loss in one or both ears, the brain attempts to adapt to the new situation.
In this case, tinnitus is generated.
This doesn’t happen in people with congenital deafness, as they haven’t perceived any type of sound input. Therefore, the auditory system hasn’t been shaped through life experience. Consequently, the tonotopic maps formed are rudimentary. There’s no somatic memory formation, and therefore, tinnitus won’t develop.
What happens if I have a cochlear implant?
Fortunately, technology has made great strides over the years in addressing hearing problems, both congenital and acquired. This is the case with the development of hearing aids and cochlear implants.
Researchers have found that tinnitus can appear in people with congenital deafness, but after receiving a cochlear implant, it is more common in the implanted ear.
Therefore, the authors of this study suggest that it is a byproduct of the formation of the corresponding somatic memory generated after activation of the implanted ear. Something similar to what happens in amputees.
Experts reveal that this whistling sound is usually only heard by people who have hearing aids and can be heard when they are turned off. Tinnitus most commonly occurs when the device is not in use, for example, when going to bed. People who have had the device fitted begin to perceive different sounds from outside. This causes their auditory memory to react to its configuration.
Thus, potentially, implants can cause tinnitus in the implanted ear if the tonotopic map has been partially restored.
Thus, when the implants are turned off, they stop perceiving sounds. Let’s say they return to their ” congenitally deaf ” state. However, their auditory memory already exists, so the brain, as we said, tries to adapt. Consequently, tinnitus begins.
This interesting work helps us understand what happens in the brain that causes these annoying ringing sounds. We are facing a complex problem that is difficult to solve and with many aspects to clarify. Now, as always, science will gradually take measures that will allow people suffering from tinnitus to coexist with their enemy.
