Inner Ear Biology
retrospectacle | December 15, 2007Over at Pharyngula, Mark Antimony posted this:
A friend of mine, who's name won't be mentioned, blacked out in class the other day. Since then, he's been on a seizure drug. The drug is giving a very weird side effect. It must be affecting his auditory cortex, because he is hearing all audio roughly a half-octave lower than what it really is. In fact, he's using a sound editing program to raise his entire music library up the ~half-octave to compensate. The name of the drug is Tegretol.
While I am not a medical doctor, my research is in auditory neuroscience so it might be interesting to…
retrospectacle | November 27, 2007The Scientist has a fastastic illustrated feature on the workings of cochlear hair cells in their current online issue. In addition to pointing out the different cell types in the inner ear, there are a few informative blurbs about mechanotransduction and how stereocilia are organized and linked. This is part of the larger theme "Focus on Neuroscience" issue, which has lots of short articles about from channel dynamics to Alzheimer's disease.
The hair cells of the inner ear are unique in that they are sensory epithelial cells, and not neural tissue themselves (like olfactory receptors or the…
retrospectacle | November 14, 2007
By Dr. Sonja Pyott
Department of Biology and Marine Biology
University of North Carolina, Wilmington
Wilmington, NC, USA
Specimen: Cochlea and Hair Cells
Technique: Confocal
This confocal microscopy image of the organ of Corti is just stunning. Judges at the Olympus Bioscapes Digital Imaging Competition thought so too, and awarded Dr. Sonja Pyott 4th prize in the contest. For an even larger, more hi-res version, go here. Winners receive Olympus microscopes and other prizes! Guess who the 1st place winner is? Yeah, its the Brainbow mouse, which I discussed in a previous post.
The image above…
aaronrowe | October 17, 2007
Since losing his hearing, Michael Chorost has volunteered himself as a guinea-pig for a number of experiments with the software that controls his cochlear implant. He has written extensively about those experiences.
This week, I stumbled upon one of his stories in The Best American Science Writing 2006 and thoroughly enjoyed it. My Bionic Quest for Bolero tells the tale of his quest to hear every nuance of his favorite song by traveling across the country and allowing a host of scientists to tweak the settings of his digital ear. I was fascinated to learn that researchers were able to…
retrospectacle | October 12, 2007The Fibonacci numbers form a sequence defined by this relation (don't be scared!):
What this means, in English, is that it is a sequence of numbers whose relationship is this: after the first two numbers, each proceeding number is the sum of the previous two numbers. For example 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233.....and so on. Quite simple, really.
Fibonacci numbers have an interesting property. When you divide one number in the sequence by the number preceding it, you are left with a number very close to 1.618. This number is called the "golden ratio," and rectangle whose…
retrospectacle | September 7, 2007I came across a good article in the New York Times which highlights the need for hearing tests for newborns: without them it is difficult to predict what might be wrong if the child is not speaking or reaching other developmental milestones.
Hearing tests are mandatory in 40 states, and routine but optional in the rest. There's a good reason for the rule:
"We need to identify children early and provide them with hearing tools and training by the time they are 6 months," said Dr. John Greinwald, a pediatric otologist at Cincinnati Children's Hospital Medical Center. Studies now confirm that…
retrospectacle | August 16, 2007The cochlea is the snail-shaped organ that mammals use to perceive and transduce sound, and is located deep in the inner ear. Hair cells lie on a membrane in the cochlea's interior, and sound waves disperse through the fluid-filled spaces which contact the hair cells (for more on this go here). Many people in the field have wondered over the year why the cochlea is shaped the way it is. Is it to conserve space? To better preserve the integrity of sound waves? Recently it has been discovered that the unique coiled shaped of the cochlea boosts its sensitivity to low frequencies, as reported in…
retrospectacle | July 4, 2007Happy 4th of July, however you'll be spending it. I'll be watching the hotdog-eating contest on TV, going to get a couple Coney dogs myself, and then fireworks of course! I gotta say that the hot dog eating contest just won't be the same without Takeru "Tsunami" Kobayashi, who is suffering from jaw arthritis. Maybe its all a ploy to think he's not gonna show.
Edit: Kobeyashi *did* show but came in a close second to Joey Chestnut.
So, in honor of doing crazy stuffs, I think I may try my hand at making some homemade sparklers. I posted this how-to last year but never got around to trying it…
retrospectacle | May 14, 2007
If you are hearing impaired, or if you just like hearing about interesting new sensory gadgets, lend me your ears. Well, actually, lend them to neuroscientists at UNC Chapel Hill who have just opened the first clinical trial to test a new device which combines cochlear implant and hearing aid technology--in the same ear. The device (which hearkens to a small handgun with a droopy trigger worn behind the ear) is shown to the right and is called the Electro-Acoustic System (EAS). This past April, two hearing-impaired North Carolina adults were the first to receive the device, and now the…
retrospectacle | April 16, 2007I got an email from the head of this study, David F. Colvard, MD, of Raleigh, North Carolina. His team has shown that nasal irrigation can help solve a common problem for scuba divers: middle ear squeeze. This refers to the phenomenon divers experience during ascent and descent in the sea, when external pressure differences cause compression in the middle ear. This can cause damage and hearing impairment, if serious. To combat this, usually divers take a decongestant in either pill or spray form. However, Dr. Colvard's study has shown that nasal irrigation helped divers achieve middle ear…
retrospectacle | April 11, 2007Well ear plugs seem to be the answer to all our hearing-loss woes, according to this short new piece I came across on CNN. The author suggests wearing earplugs during incredibly noisy tasks as well as everyday ones, which is ok, but rather unrealistic. Who's really going to drop hundreds on custom ear-plugs, or wear plugs during aerobics (yeah, they fall out), or during a rock concert where you want to *enjoy* the music, not muffle it. And the author also brings out the tired song and dance about earbuds/iPods being bad for your hearing (they aren't any worse than previous technology, and…
retrospectacle | April 4, 2007A recent New Scientist article (March 2007) does a pretty decent job summarizing the current state of hair cell regeneration in mammals, including the work coming out of my lab. May require a subscription or institutional access.
Here's a few of the figures from the article that I thought weren't half bad (in a popup for high resolution). View image
Hat tip Bob Abu.
retrospectacle | April 3, 2007This vaccine wasn't meant to prevent ear infections per se, but has had the welcome side effect of doing just that (for more on ear infections, go here). Pharmaceutical company Wyeth developed the vaccine PCV7 (marketed in the US under Prevnar) to ward off common bacterial infections, and has been around since 2000. However, children who received the vaccine had significantly less ear infections and a lower incidence of "tubes in the ears." (For more on ear tubes, go here.)
The vaccination, given initially at 2, 4 and 6 months of age, was designed to combat a number of pneumococcal infections…
retrospectacle | April 2, 2007The first "smart" robotic micro-drill has been used on a handful of patients in the UK, with very positive outcomes. It was developed by Dr. Peter Brett from the School of Engineering and Applied Science at Aston Univ. and first used in surgery by an ear, nose, and throat doctor who found the drill useful for patients who need cochlear implants.
Perfect for making tiny holes in breakfast foods.
The drill is applied to the cochlea, the inner ear hearing organ, is aligned to the correct place and then drills a hole less than a millimetre in diameter to enable the cochlear implant to be…
retrospectacle | March 9, 2007As I've mentioned before, my research and my lab focuses on the delivery of genes to the inner ear to repair or reverse deafness. One potential method for getting these genes into surviving cells is to insert them into a modified virus which infects the healthy inner ear cells. Following infection, the cells produce the protein of interest instead of more virus. However, this method's strength is in proof of concept rather than a direct therapy.
However, a group at Emory has devised yet another way to treat genetic deafness: compensating for a missing protein. A common cause of genetic…
retrospectacle | March 8, 2007Bob Abu sent me this really amazing website on inner ear biology and morphology. Its got some really impressive SEM pictures and very informative descriptions of the anatomy of the cochlea. I'd suggest checking it out.
Cross-section of the sensory portion of the cochlea (the organ of Corti.)
retrospectacle | February 22, 2007 NASA loves to use weird science to make useful stuff.....even proteins found in the inner ear, in the hair cells to be exact. The protein is called prestin, which is the motor protein on hair cells, which may also find a new use powering space suits. If prestin is combined with electricity-producing microbes (geobacter) in a suit, NASA hopes it will result in the physical motion of the astronaut (and even gusts of wind) being converted into energy. Cool!
Outer hair cells can contract and expand in response to sound, which results in an amplification of auditory stimulus. Prestin changes the…
retrospectacle | February 14, 2007
A great learning tool online is Promenade 'Round the Cochlea, which is in both French and English. I've just been swamped during the conference, but my presentation went great yesterday and I got lots of feedback to keep me busy with experiments forever and ever Ramen. Anyway, check out the app, as it does a great job of explaining some aspects of inner ear biology with pictures. Also, Happy Valentines!
retrospectacle | February 7, 2007This week I've been talking a bit about deafness and human hearing. A human cochlea is tiny, and is located in a bony stucture near in the skull called the bulla of the temporal bone. The temporal bone is oft said to be the hardest bone in the body. Predictably, almost all other mammals share this structure (the bulla), as a protective shield around the inner ear. Humans' bulla are quite small, about the size of a large marble, but that of a whale's (and especially, a blue whale) is enornous, reaching sizes of a Nerf football. (See picture below the fold of bulla taken from a 20 ft humpback…
retrospectacle | February 6, 2007 Yeah, I know what you must be thinking: What a weird and ridiculous title. However, trust me, it actually does make sense. In yesterday's basic concepts post on Hearing, I explained that sound is transduced in the inner ear by hair cells in the cochlea. Specifically, that the deflection of hair cells' "hairs" (the stereocillia) cause ions to enter the cell and subsequently stimulate nerves which project to auditory processing centers. All this depends on the stereocillia being properly formed and rigid----but what happens if the stereocillia are too floppy?
A recent discovery by a team at…