Scientists studying tinnitus have made a discovery in animal models that they believe shows that the hearing disorder occurs due to overactive neurons. They are currently developing a device to calm the hyperactive nerve cells.
A team of researchers from the University of Michigan Medical School induced tinnitus in guinea pigs, Medical News Today reports. Their findings, published in the Journal of Neuroscience, suggest that tinnitus occurs after alteration of a process in animals known as stimulus-timing dependent multisensory plasticity. They claim that this plasticity is incredibly sensitive to the timing of signals going to an important part of the brain.
Tinnitus is actually a symptom of a hearing disorder, according to the Mayo Clinic. Most people consider the term a synonym for ringing in the years. However, it's a sign of disorders like age-related hearing loss, ear injury, or a circulatory system problem.
Patients report buzzing, roaring, ringing, clicking, hissing, and a number of other annoying sounds. For some, the noise -- which isn't real, but merely a perception -- is intermittent. However, for those who experience it continually, it can be debilitating. There is no cure.
The National Institute on Deafness and Other Communication Disorders estimates that approximately 25 million Americans have experienced tinnitus. The disorder affects around 14 percent of females and more than 12 percent of males at least 65 years old.
Signals coming from the auditory nerve enter the brain at the dorsal cochlear nuclear. Neurons in that region pick up the signals and integrate them with information from other senses. The scientists noted that in animals with tinnitus, signals from somatosensory nerves in the neck and the face, which are linked to touch, become amplified in the presence of reduced ear sounds.
Lead author Prof. Susan Shore indicates that while the signals are apparently trying to compensate for reduced sounds from the ear, they manage to go into overdrive. This causes the perception of noise in tinnitus. Researchers speculate this is why some tinnitus patients are able to alter the pitch and the volume of perceived sounds by moving the neck and head or clenching teeth.
The Michigan team concluded that the exact timing of the signals in relation to each other alters the plasticity of the nervous system. When they attempted to induce tinnitus in guinea pigs, just half developed it. Among those who remained normal, the scientists observed fewer changes in plasticity.
The researchers are currently developing a device to treat tinnitus. It combines electrical stimulation of the neck and face with sound. The objective is returning neural activity to a normal level. When it's ready for human use, healthcare providers will need to customize the device to meet each patient's needs and provide treatment on a regular basis.
Vonda J. Sines has published thousands of print and online health and medical articles. She specializes in diseases and other conditions that affect the quality of life.