Friday, March 9, 2012

Modulation of Sound Sensitivity

An interesting discovery by researchers with be published in Neuroscience regarding the hair cells of the inner ear. Using a high voltage electron microscope, the researchers determined that the rootlets of the hair cells continue through the cell to the striated organelle which is believed to be responsible for the cell's stability. With the striated organelle connecting the rootlets to the cell membrane, this offers the opportunity of feedback from the cell to the very detectors that detect motion. One of the researchers states the following: "this suggests a new way to envision how hair cells work. Just as the brain adjusts the sensitivity of retinal cells in the eye to light, it may also modulate the sensitivity of hair cells in the inner ear to sound and head position". Feedback from the brain could be what changes the tension on the rootlets of the hair cells and their sensitivity to stimuli.

Do you find that children with sound sensitivity also have vestibular processing problems or vice versa? I have been looking for research on this topic and have come up with some that states vestibular processing problems may be associated with auditory processing problems but have come up empty handed on sound sensitivity. Can anyone offer any insight? Thanks in advance.

 Reference: University of Illinois at Chicago (2012, March 8). Discovery of hair-cell roots suggests the brain modulates sound sensitivity. ScienceDaily. Retrieved March 9, 2012, from­ /releases/2012/03/120308174651.htm


Chris said...

Children who have hearing impairments are at risk for altered balance. There are also conditions like Meniere's disease where there is altered hearing sensitivity and vestibular function. There is also the (apparent) auditory hypersensitivity of children who have autism and their risk for lower performance on motor skills tasks. So, there seems to be evidence that hearing sensitivity and lack of sensitivity might be sometimes related to balance or motor skill... but there are too many confounding variables to say for sure. As you know, correlation does not indicate causation.

I have not seen any studies that control variables cleanly enough to support claims that auditory stimulation as an intervention will improve vestibular function, but that certainly hasn't stopped those on the continuing ed circuit and the droves of people who like those courses. Oh well.

Have a good weekend.


Bea, OT said...

My son who suffered a stroke, is sensitive to sounds and also displays mild vestibular processing problems. I have used therapeutic listening techniques, SI, and Masgutova techniques with success. He started walking at 10 months and is on target with all his milestones.

In my experience, I have used vestibular based treatment to help with hearing sensitivity with good results. I have not yet seen research to support this, though it would be great if someone would study it!

Your Therapy Source Inc said...

Thank you Chris and Bea for commenting. That was exactly the type of research I was looking for Bea - vestibular stimulation effecting auditory hypersensitivity. To me, from a neuroanatomy perspective it seems as if gaining control over the vestibular system may help in auditory sensitivity. But that brings us back to the puzzle of what Chris mentioned - how do we single out those variables to show causation. On the flip side I do not "believe" (I know bad choice of words when discussing research) that auditory stimulation can change vestibular function from a neuroanatomical perspective. I do think it may help by providing rhythm to motion but that it does not change any neurological process. I just wish I could find research to back up my "beliefs" or maybe understanding is a better choice of words. Thanks again for the comments.

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