December 20, 2010:
Temporary hearing deprivation can lead to ’lazy ear’
It is well-known by scientists that degraded sensory experience during childhood may cause ‘lazy eyes’. But an American study shows likewise that short-term hearing deprivation at an early age may result in ‘lazy ears’.
Scientists have gained an insight into why a relatively short-term hearing deprivation during childhood may lead to persistent hearing deficits long after hearing is restored to normal. The research shows that the auditory cortex is quite vulnerable if it does not receive appropriate stimulation at just the right time.
This vulnerability has already been proven by scientists, who declare that degraded sensory experience during critical periods of childhood development can have detrimental effects on the brain and behavior. The phenomenon is called amblyopia, also known under the name ‘lazy eye’, and can arise when balanced visual signals are not transmitted from each eye to the brain during a critical period for visual cortex development.
Viscous fluid degrades hearing ability
“An analogous problem may exist in the realm of the hearing, in that children commonly experience a buildup of viscous fluid in the middle ear cavity, called otitis media with effusion, which can degrade the quality of acoustic signals reaching the brain and has been associated with long-lasting loss of auditory perceptual acuity,” explains one of the researchers, Dr. Daniel Polley from the Massachusetts Eye and Ear Infirmary.
His team observed that the temporary hearing loss in one ear distorted auditory patterning in the brain, weakened the deprived ear’s representation and strengthened the open ear’s representation.
Recovery through training
“The good news about amblyaudio is that it is unlikely to be a permanent problem for most people,” explains Dr. Polley and continues:
“Even if the acoustic signal isn’t improved within the critical period, the mature auditory cortex still expresses a remarkable degree of plasticity. We are gearing up now to study whether auditory perceptual training may also be a promising approach to accelerate recovery in individuals with unresolved auditory processing deficits stemming from childhood hearing loss.”
Source: Cell press, March 11 issue of the journal Neuron
Taken from www.eurekalert.org