Related Experiment Video
Updated: Jun 21, 2026
06:07
Isolation and Culture of Primary Cochlear Hair Cells from Neonatal Mice
Published on: September 15, 2023
Abnormal cochlear potentials from deaf patients with mutations in the otoferlin gene.
Rosamaria Santarelli1, Ignacio Del Castillo, Montserrat Rodríguez-Ballesteros
1Department of Medical and Surgical Specialities, Service of Audiology and Phoniatrics, University of Padua, Via Giustiniani 2, I-35128, Padua, Italy. rosamaria.santarelli@unipd.it
Summary
Mutations in the otoferlin (OTOF) gene cause severe hearing loss by impairing neurotransmitter release from inner hair cells. This study reveals abnormal cochlear potentials in children with OTOF mutations, indicating impaired auditory nerve function.
Area of Science:
- Genetics
- Neuroscience
- Audiology
Background:
- Otoferlin (OTOF) is crucial for neurotransmitter release at the inner hair cell (IHC) synapse.
- OTOF gene mutations lead to severe-to-profound hearing loss, often presenting as auditory neuropathy.
- Understanding the physiological impact of OTOF mutations is vital for diagnosing and treating hearing impairments.
Purpose of the Study:
- To investigate the physiological effects of OTOF mutations on sound-evoked cochlear potentials in children.
- To evaluate neurotransmitter release function in human subjects with OTOF mutations using electrocochleography.
- To compare cochlear potential characteristics between children with OTOF mutations and normally hearing children.
Main Methods:
- Transtympanic electrocochleography was used to record sound-evoked cochlear potentials in four children with OTOF mutations.
- Cochlear potentials were analyzed for amplitude, polarity, and duration in response to click stimuli.
- Recordings from affected children were compared to those from 16 normally hearing children.
Main Results:
- Cochlear microphonic (CM) amplitudes were generally normal, suggesting intact mechano-electrical transduction.
- Post-CM cochlear potentials showed reduced amplitude and prolonged duration, with negative polarity.
- Auditory nerve compound action potentials were absent or low amplitude, while summating potentials were mostly normal.
- These findings suggest impaired neurotransmitter release from IHCs, affecting auditory nerve activation.
Conclusions:
- Mechano-electrical transduction and cochlear amplification appear normal in individuals with OTOF mutations.
- Abnormal, low-amplitude, prolonged negative cochlear potentials indicate impaired neurotransmitter release from IHCs.
- This dysfunction leads to abnormal dendritic activation and impaired auditory nerve firing, explaining the profound hearing loss.
Related Concept Videos
01:13The Cochlea
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.
01:22Hair Cells
Hair cells are the sensory receptors of the auditory system—they transduce mechanical sound waves into electrical energy that the nervous system can understand. Hair cells are located in the organ of Corti within the cochlea of the inner ear, between the basilar and tectorial membranes. The actual sensory receptors are called inner hair cells. The outer hair cells serve other functions, such as sound amplification in the cochlea, and are not discussed in detail here.
01:15Auditory Pathway
Auditory pathways constitute the complex neural circuits responsible for transmitting and interpreting auditory information from the peripheral auditory system to the brain. Sound waves are initially captured by the outer ear, funneled through the ear canal, and reach the tympanic membrane (eardrum). These vibrations are transmitted via the middle ear's ossicles to the inner ear's cochlea.
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
01:16Anatomy of the Ear
Auditory sensation, commonly called hearing, involves the transformation of sonic waves into neural impulses facilitated by the structures of the auditory organ. The prominent, flesh-like structure on the side of the head, called the auricle, directs sound waves towards the auditory canal. The auricle is often mislabeled as the pinna, a term more aligned with mobile structures like a feline's external ear. The auditory canal penetrates the cranium via the external auditory meatus of the...