FY2004 President's Budget Request for the NIDCD

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Fiscal Year 2004 President's Budget Request
for the National Institute on Deafness and Other Communication Disorders

Statement by
Dr. James F. Battey, Jr.
Director, National Institute on Deafness and Other Communication Disorders

Mr. Chairman and Members of the Committee, I am pleased to present the President's budget request for the National Institute on Deafness and Other Communication Disorders (NIDCD). The fiscal year (FY) 2004 budget includes $380,377,000, which reflects an increase of $10,190,000 over the FY 2003 enacted level of $370,187,000 comparable for transfers proposed in the President's request. Disorders of human communication exact a significant economic, social, and personal cost for many individuals. The NIDCD supports research and research training in the normal and disordered processes of hearing, balance, smell, taste, voice, speech, and language. Results of NIDCD's research investment will foster the development of more precise diagnostic techniques, novel intervention and prevention strategies, and more effective treatment methods for the millions of Americans with communication disorders. My testimony will highlight some examples of research progress in human communication sciences.

Cochlear Implants. If Ludwig van Beethoven were able to reverse his deafness and regain his hearing again as he reached the climax of his career as a composer, would the world have been blessed with even more of his music? Scientific technology has advanced significantly since the 18th century, and assistive hearing devices are now able to restore sound perception to deaf individuals. One such device, the cochlear implant, has provided hope to thousands of deaf individuals worldwide. A cochlear implant converts sound into electrical impulses, bypassing the damaged sensory hair cells that detect sound, stimulating the auditory nerve directly and restoring sound perception. According to the Food and Drug Administration 2002 data, approximately 59,000 people worldwide have received cochlear implants. In the U.S., about 13,000 adults and nearly 10,000 children have received them. With over 30 years of NIH research investment, the cochlear implant has evolved from an experimental device to a commercially available treatment to assist those who are profoundly deaf or severely hearing impaired.

Hereditary Deafness Gene Discovery. Within the last seven years, over 70 different genes for hearing loss that is not associated with other inherited characteristics (nonsyndromic hereditary hearing impairment) have been mapped and over 25 identified. In addition, several genes essential for normal auditory development and/or function have been identified using mouse models. Recently, scientists have discovered a new gene of unknown function, TMC1, in which mutations cause deafness. NIDCD intramural scientists have identified a mutation in the mouse Tmc1 gene which causes similar types of dominant and recessive hearing loss found in large human family studies. In mice, mutations in the Tmc1 gene causes defects in the function of the specialized sensory hair cells of the inner ear. Hair cells detect and convert the physical stimulus of sound into electrical impulses sent to the brain via the auditory nerve. This research contributes to new models for studying specific forms of human deafness.

Sensory Stereocilia Renewal Aid Recovery to Hearing Loss. Stereocilia, or hair cell bundles, are fine projections in the inner ear that vibrate when stimulated by sound. The movement of the stereocilia activates a molecular pathway that generates an electrical signal from the auditory nerve to the brain, which is interpreted to be sound. Stereocilia are located in the surface of the inner ear and are supported by a rigid and dense core of filaments. Until recently, this core was thought of as a stable structure whose sole function was to serve as rigid supports for changes in the mechanical property of the hair cells. NIDCD intramural scientists have discovered that there is a continuous renewal of the stereocilia core every 48 hours. This process occurs in the mature bundles during recovery from temporary noise-induced hearing loss and suggests that the stereocilia core structure plays an unforeseen role in this recovery process. Such a renewal mechanism could also provide more information on the molecular basis of genetic, environmental, and age-related inner ear disorders that involve malformation or disruption of stereocilia.

Motor Protein Facilitates the Speed of Sound. One important component in the mechanical transmission of sound from the ear to the brain is Myosin-1C, a major motor protein involved in the movement of the stereocilia in the inner ear. It is hypothesized that motor proteins serve as the link between the stereocilia's membrane and cell core thereby changing the polarity of hair cells following sound vibration. NIDCD-supported scientists are in the process of deciphering how Myosin-1C works. Specifically, they used a chemical-genetic approach to inhibit Myocin-1C motor protein activity in mice by introducing a custom designed amino acid that alters the protein's function. The designer amino acid rendered the protein susceptible to a controllable inhibitor, thus allowing regulation of the protein's motor function. These results demonstrate the importance of Myosin-1C in transmitting sound to the brain, allows observation of protein function in a controllable native environment and permits assessment of protein function in a biological process.

Antibiotic Controls the Vertigo of Ménière's Disease. Ménière's disease is a distressing and often disabling disorder of inner ear function, characterized by spontaneous attacks of vertigo, fluctuating hearing loss, tinnitus and fullness in the ear. When vertigo cannot be controlled by diet or medication, severing of a vestibular nerve from the affected ear usually controls vertigo while preserving hearing. NIDCD-supported scientists have demonstrated that a single injection of the antibiotic, gentamycin, through the eardrum into the middle ear space, is an alternative to surgery and is effective in diminishing vestibular response and in controlling vertigo in individuals with Ménière's disease. Experimental studies suggest that gentamycin reduces vestibular responsiveness, and hence, vertigo, by causing a toxic effect on the vestibular hair cells, the sensory receptors that detect head motion stimuli and orientation.

Odorant Receptors Help Mosquitoes Smell Their Prey. The sense of smell (olfaction) plays an important role for blood-feeding female mosquitoes in finding a host. Mosquito-borne disease is a serious world health concern, and the mosquito is known to transmit a variety of deadly diseases, including malaria, West Nile virus, dengue and yellow fever. Host preference, especially to humans, in the female mosquito is a critical component of disease transmission. NIDCD-supported scientists are characterizing the genes that play a role in the function of the olfactory system of Anopheles gambiae and have identified odorant receptor-encoding genes selectively expressed in the olfactory organs of this malaria-transmitting mosquito. Blood-feeding and host preference selection involve only the female mosquito, so the scientists studied the expression of odorant receptor genes, AgOr, in the female mosquito's primary olfactory organ - its antennae. It was observed that AgOr1 is turned off in the olfactory tissue of the female mosquito 12 hours after a blood meal, which is consistent with decreased host-seeking behavior. These findings suggest that AgOr1 may detect an olfactory signal that is active in female mosquitoes before but not after a blood meal. Developing selective antagonists to AgOr1 may help to control the transmission of malaria and other mosquito-borne diseases, and may also represent a novel disease prevention approach that is based on an understanding of olfactory receptor genes. In addition, these findings may ultimately be useful in developing new repellants and attractants that are more effective, economical and ecologically friendly.

Discovery of an Amino Acid Taste Receptor. Taste is responsible not only for attraction and repulsion to various foods but is also responsible for providing important information about the chemical environment. The basic taste qualities are sweet, sour, salty, bitter and umami (the taste of monosodium glutamate or the taste associated with protein-rich foods). A major challenge in taste research is identifying the various types of taste receptors on the tongue that respond to different structurally diverse compounds. Recently, scientists have identified a taste receptor dedicated to tasting amino acids, the building blocks of proteins that are involved in the biological processes in the body. It has been known that sweet-, bitter- and umami-tasting substances activate G-protein-coupled receptors in the tongue. NIDCD-supported scientists discovered that two subunits in the T1R receptor family, T1R1 and T1R3, can combine to form an amino acid receptor, T1R1+3, that responds to most of the 20 standard amino acids. Identification of an amino acid taste receptor provides a new tool to help scientists decode the molecular basis for detecting different taste qualities in mammals.

Do Stutterers Have Different Brains? To study the brain activity patterns in the cortical speech-language areas of the brain of individuals who stutter, NIDCD-supported scientists performed brain imaging studies on two groups of adults; those with or without persistent developmental stuttering (PDS). Results of the analysis showed that differences in the speech-language areas of the brain are more common in adults with PDS, although no one anatomic feature accounted for the group differences. The major anatomic finding was that the size of the right and left planum temporale (PT) of the brain were significantly larger in the adults with PDS. The PT is important for higher order processing of language information. The results about the PT size and other findings, such as variations of infolding patterns of the brain, demonstrate that atypical size or shape of the speech-language area may put individuals at risk for stuttering.

Speech-Sound Disorders are Risk for Later Academic Impairments. Children with speech-sound disorders often have difficulties in other areas of language as well. These disorders are characterized by the inability to use speech sounds that are normal for the individual's age and dialect. Speech-sound disorders involve language difficulty affecting an individual's ability to learn and organize speech sounds into a system of sound patterns. Poor awareness of speech skills and a weakness in vocal sound classification in verbal memory may put children of preschool age with speech-sound disorders at risk for later spelling difficulties. In a recent NIDCD-supported study, the spelling errors of children with history of speech-sound disorders were analyzed to predict the association between weaknesses in spoken language skill in early childhood and school-age spelling abilities. The findings of this study support previous research indicating that children with early speech-sound disorders are at risk for later spelling difficulties. Evidence from studying these families raises the possibility of a common genetic cause for speech/language and written language disorders. Although the genetic cause for these disorders is not known, specific signs of the disorder suggest a male gender bias since brothers were also more likely to have the disorder than sisters. The findings of this study reveal that preschool children with speech-sound disorders are at risk for later spelling impairments even after productive speech disorders have resolved.

A Possible Gene for Childhood Language Disorders. Children who fail to develop language normally (in the absence of factors such as neurological disorders, hearing impairments, or lack of adequate opportunity) have specific language impairment (SLI). SLI has a prevalence of approximately 7% in children entering school and is associated with later difficulties in learning to read. Research studies have consistently demonstrated that SLI clusters in families, suggesting that genetic factors may be an important cause of SLI. NIDCD-supported scientists are scanning the genome for the location of the gene suspected of causing SLI, by studying families where multiple members have with language/reading disorders. The study showed significant evidence of a link between a region of chromosome 13 and susceptibility to SLI. Further analysis also suggests two additional gene locations on chromosomes 2 and 17 that may play a role in SLI. In addition, mutations in the same region in chromosome 13 is implicated in autism, and some children with autism show language deficits that are very similar to SLI.

Mr. Chairman and Members of the Committee, these are just a few examples of NIDCD's research advances. I would be pleased to answer any questions you may have.

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