PAETE.ORG FORUMS
Paetenians Home on the Net

HOME | ABOUT PAETE | USAP PAETE MUNISIPYO  | MEMBERS ONLY  | PICTORIAL PAETE | SINING PAETE  | LINKS  |

FORUM GUIDELINES
please read before posting

USAP PAETE Forum Index USAP PAETE
Discussion Forums for the people of Paete, Laguna, Philippines
 
 FAQFAQ   SearchSearch    UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

(Anatomy) Hearing: Poor Hearing May Cause Poor Memory
Goto page Previous  1, 2
 
Post new topic   Reply to topic   printer-friendly view    USAP PAETE Forum Index -> Science Lessons Forum
View previous topic :: View next topic  
Author Message
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Sat Dec 15, 2007 1:31 pm    Post subject: Cholesterol fine tunes hearing Reply with quote

Baylor College of Medicine
14 December 2007

Cholesterol fine tunes hearing

Levels of cholesterol in the membranes of hair cells in the inner ear can affect your hearing, said a consortium of researchers from Baylor College of Medicine, Rice University and Purdue University in a report in today’s print edition of The Journal of Biological Chemistry.

Dr. William Brownell, professor of otolaryngology at BCM and his colleagues, said that the amount of cholesterol in the outer hair cell membrane found in the inner ear can affect hearing.

“We’ve known for a long time that cholesterol is lower in the outer hair cell membranes than in the other cells of the body,” said Brownell, senior author of the report “What we didn’t know was the relationship it had to hearing.”

Dr. Lavanya Rajagopalan, postdoctoral fellow in otolaryngology at BCM, led the research team that manipulated the cholesterol levels in outer hair cells of mice. She and her colleagues measured the mice’s hearing ability by a technique that uses inaudible sound waves emitted from the ear as it reacts to external sound. There are two types of sensory hair cells in the inner ear called the inner and outer hair cells. It is the outer hair cells that are affected by cholesterol levels and produce the inaudible sounds in the ear canal.

“Depleting the cholesterol resulted in a hearing loss. Adding cholesterol initially increased hearing but later resulted in a hearing loss,” Brownell said. “So you can change an animals hearing just by adding or subtracting cholesterol.”

The fine tuning of the cholesterol happens naturally in development and does not change significantly after birth. In contrast, cholesterol in the bloodstream can vary with eating habits. That is why avoiding fatty foods can promote a healthy heart.

“Will our hearing be affected if we continually eat greasy meals" Right now, we don’t see a connection between the two,” Brownell said. “The results of the study help us understand the cellular mechanisms for regulating hearing and give us another way to potentially help those with hearing loss.”


###
Others who took part in the study include Drs. Anping Xia, Angela Sturm, John S. Oghalai, Fred A. Pereira, and research assistant Haiying Liu of BCM, Jennifer N. Greeson and Dr. Robert M. Raphael of Rice University and Dr. Amy L. Davidson of Purdue University.

This study was supported by grants from the National Institute of Deafness and Other Communication Disorders, the National Science Foundation, the Deafness Research Foundation, the Keck Center for Interdisciplinary Bioscience Training and the Welch Foundation.

A preliminary version of the article is available at http://www.jbc.org/cgi/reprint.....type=HWCIT
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Wed Jan 02, 2008 9:26 am    Post subject: Silence may lead to phantom noises misinterpreted as tinnitu Reply with quote

American Academy of Otolaryngology, Head and Neck Surgery
1 January 2008

Silence may lead to phantom noises misinterpreted as tinnitus

New research from the journal Otolaryngology -- Head and Neck Surgery
Phantom noises, that mimic ringing in the ears associated with tinnitus, can be experienced by people with normal hearing in quiet situations, according to new research published in the January 2008 edition of Otolaryngology – Head and Neck Surgery.

The Brazilian study, which consisted of 66 people with normal hearing and no tinnitus, found that among subjects placed in a quiet environment where they were asked to focus on their hearing senses, 68 percent experienced phantom ringing noises similar to that of tinnitus. This is compared to only 45.5 percent of participants who heard phantom ringing when asked to focus on visual stimuli and not on their hearing, and 19.7 percent of those asked to focus on a task in a quiet environment.

The authors believe that these findings show that with regards to tinnitus, the role of attention to symptoms, as well as silence, plays a large role in experience and severity.

Tinnitus, an auditory perception that cannot be attributed to an external source, affects at least 36 million Americans on some level, with at least seven million experiencing it so severely that it interferes with daily activities. The disorder is most often caused by damage to the microscopic endings of the hearing nerve in the inner ear, although it can also be attributed to allergies, high or low blood pressure (blood circulation problems), a tumor, diabetes, thyroid problems, injury to the head or neck, and use of medications such as anti-inflammatories, antibiotics, sedatives, antidepressants, and aspirin.

###
Otolaryngology – Head and Neck Surgery is the official scientific journal of the American Academy of Otolaryngology – Head and Neck Surgery (AAO-HNS). The study’s authors are Keila Alessandra Baraldi Knobel, MSc and Tanit G. Sanchez, MD, PhD. They are associated with the University of Sao Paulo Medical School in Sao Paulo, Brazil.
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Thu Jan 10, 2008 7:48 pm    Post subject: Auditory neurons in humans far more sensitive to fine sound Reply with quote

University of California - Los Angeles
10 January 2008

Auditory neurons in humans far more sensitive to fine sound frequencies than most mammals

Researchers implant electrodes in the brain, and use the soundtrack from 'The Good, the Bad and the Ugly'
The human ear is exquisitely tuned to discern different sound frequencies, whether such tones are high or low, near or far. But the ability of our ears pales in comparison to the remarkable knack of single neurons in the brain to distinguish between the very subtlest of sound frequencies.

Reporting in the January 10 issue of the journal Nature, Dr. Itzhak Fried, a professor of neurosurgery and director of the epilepsy surgery program, and colleagues at the Hebrew University in Jerusalem and the Weizmann Institute of Science, show that in humans, a single auditory neuron in the brain exhibits an amazing selectivity to a very narrow sound frequency range, roughly down to a tenth of an octave. In fact, the ability of these neurons to detect the slightest of differences in sound frequencies far exceeds that of the auditory nerve that carries information from the hair cells of the inner ear to the cortex as much as 30 times more sensitivity. Indeed, such frequency tuning in the human auditory cortex is substantially superior to that typically found in the auditory cortex of non-human mammals, with the exception of bats.

It is quite a paradox, the researchers note, in that even musically untrained people can detect very small sound frequency differences, much better than the resolution of the peripheral auditory nerves. This is very different from other peripheral nerves, such as those in the skin, where the human ability to detect differences between two points (say from the prick of a needle) is limited by the receptors in the skin. Not so in hearing.

The researchers, including senior author Israel Nelken and first author Yael Bitterman from the Hebrew University, determined how neurons in the human auditory cortex responded to various sounds by taking recordings from four consenting clinical patients at the UCLA Medical Center. These patients had intractable epilepsy, and were being monitored with intracranial depth electrodes to identify the focal point of their seizures for potential surgical treatment. Using clinical criteria, electrodes were implanted bilaterally at various brain sites that were suspected to be involved in the seizures; these included the auditory cortex. The recording of brain activity was carried out while the patients listened to artificial random chords at different tones per octave, and to segments from the film “The Good, the Bad and the Ugly.’’ Thus, the sounds the patients heard were both artificial—the random chords—and more natural, the voices and noise from the movie soundtrack.

The results surprised the researchers. A single auditory neuron from humans showed an amazing sensitivity to distinguish between very subtle frequency differences, down to a tenth of an octave. This compared to a sensitivity of about one octave in the cat, about a third of an octave on average in rats, and half to one octave in the macaque.

“This is remarkable selectivity,” said Fried, who is also the co-director of UCLA’s Seizure Disorder Center. “It is indeed a mystery why such resolution in humans came to be. Why did we develop this? Such selectivity is not needed for speech comprehension, but it may have a role in musical skill. The three percent frequency differences that can be detected by single neurons may explain the fact that even musically untrained people can detect such frequency differences.

“There is also evidence that frequency discrimination in humans correlates with various cognitive skills, including working memory and the capability to learn, but more research is needed to clarify this puzzle.”

This study, said Fried, is the latest example of the power of neurobiological research that uses data drawn directly from inside a living human brain at the single-neuron level. Previous studies from Fried’s lab have identified single cells in the human hippocampus specific to places during human navigation, and single cells that can translate varied visual images of the same item, such as the identity of an individual, into a single instantly and consistently recognizable concept.
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Mon Aug 25, 2008 11:38 am    Post subject: Evolution's Ear Reply with quote

Evolution's Ear
By Bruce Bower
August 30th, 2008;
Vol.174

Recent changes in hearing-related genes may have influenced language

Imagine, for a moment, that you are smaller than a speck of dust and in the mood for some teeny-tiny sightseeing. It’s a perfect opportunity to take a scenic trip to the inner ear.


For the full article:

http://sciencenews.org/view/fe.....utions_Ear
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic   printer-friendly view    USAP PAETE Forum Index -> Science Lessons Forum All times are GMT - 5 Hours
Goto page Previous  1, 2
Page 2 of 2

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group