Glutamate Toxicity and neuronal cells...
in neurons, cells & liver to detoxify heavy metals. Low levels ... well as hyperacusis, otitis media, and conductive hearing loss, in a ...
exposed to thimerosal in ear drops,
http://www.the7thfire.com/PycResGlutamateTox.htmThe auditory system is damaged by mercury poisoning in Minamata disease.
The auditory system may have special importance for the brain as a whole. Fisch (1970) pointed out that the auditory system is always active, even during sleep [118] -- this is why we use alarm clocks to wake up!
The auditory system evolved as an alerting mechanism for visual attention, and there is evidence that the inferior (auditory) and superior (visual) colliculi in the midbrain tectum might have special importance for general awareness and consciousness [119, 120].
Hyperacusis
The EideNeurolearning blog reports on a study into Williams Syndrome (also called Williams-Beuren syndrome), a genetic disorder characterised by mental retardation coupled with an unusual facility with language and a love for music. Because of the nature of the syndrome it made a good study on sound sensitivity. Carers of people with Williams Syndrome where asked to complete questionnaires on what and how sounds effected them and these where compared to the answers given by people with Down Syndrom, autism and a normal control group.
Normally sound sensitivity is referred to as Hyperacusis but this term is used to describe various behaviours. The study, 'Aversion, Awareness, and Attraction: Investigating Claims of Hyperacusis in the Williams Syndrome Phenotype' [PDF], found four different sound related behavior.
True Hyperacusis: Lowered hearing thresholds
Odynocusis: Lowered auditory pain threshold
Auditory Allodynia: Aversion or fear of sounds not normally aversive
Auditory Attractions: Attractions to or fascinations with certain sounds
True Hyperacusis was only found in the people with Williams Syndrome and then only in 4.7% of the group. Odynacusis and Auditory Allodynia was found in 70%+ of the Williams Sydnrome group and around 30% in the autistic group compared with 2% of normal control group. Interestingly some of the behaviour exhibited by the people with Williams Syndrome is remarkably similar to obsessive behaviour seen with autism through with sounds rather than the more common tactile obsessions seen in autism: "... one young adult spontaneously said that he loved the sound of vacuum cleaners. His parents reported that he owned 18 vacuum cleaners ...". The negative reactions to some sounds were also reminiscent of autism: "One child in our study covered her ears and cried to her mother that the birds outside were ‘hollering’ at her. One 17-year-old girl reported extreme distress from the sound of a vacuum cleaner in another room, explaining that ‘the sound reverberates in my head.’"
At an approximately 30%+ incident rate, its obvious that sound sensitivity is significant in autism and sheds light on some autistic behaviour. See also The Senses of Autism and Hearing Things.
http://en.wikipedia.org/wiki/Mercury_%28element%29From the mid-18th to the mid-19th centuries, a process called "carroting" was used in the making of felt hats. Animal skins were rinsed in an orange solution of the mercury compound mercuric nitrate, Hg(NO3)2•2H2O. This process separated the fur from the pelt and matted it together. This solution and the vapors it produced were highly toxic. Its use resulted in widespread cases of mercury poisoning among hatters. Symptoms included tremors, emotional lability, insomnia, dementia and hallucinations. The United States Public Health Service banned the use of mercury in the felt industry in December 1941. The psychological symptoms associated with mercury poisoning may have inspired the simile "mad as a hatter", and thereby the Mad Hatter of Alice in Wonderland fame.
http://en.wikipedia.org/wiki/Hallucinationhttp://en.wikipedia.org/wiki/Auditory 
