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Updated: Jul 9, 2026
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Cochlear Implant Surgery and Electrically-evoked Auditory Brainstem Response Recordings in C57BL/6 Mice
Published on: January 9, 2019
Cochlear implants stimulate activity-dependent CREB pathway in the deaf auditory cortex: implications for molecular
Justin Tan1, Sandra Widjaja, Jin Xu
1The Bionic Ear Institute, East Melbourne, Victoria 3002, Australia. jtan@bionicear.org
Cerebral Cortex (New York, N.Y. : 1991)
|December 8, 2007
Summary
Sensorineural hearing loss decreases key proteins for synaptic plasticity. Cochlear implants restore these proteins, suggesting molecular adaptations in the auditory cortex.
Area of Science:
- Neuroscience
- Molecular Biology
- Auditory Neuroscience
Background:
- Neural activity and signaling pathways regulate synapse maturation and functional circuit development.
- Phosphorylation of cyclic AMP/Ca(2+)-responsive element-binding protein (CREB) is a stimulus-inducible event crucial for synaptic plasticity.
- Brain-derived neurotrophic factor (BDNF) transcription, activated by phosphorylated CREB (pCREB), is vital for synaptic transmission and long-term potentiation.
Purpose of the Study:
- To investigate the molecular effects of sensorineural hearing loss and cochlear implantation on CREB and BDNF expression in the auditory cortex.
- To explore the role of the mitogen-activated protein kinase (MAPK) signaling pathway in adaptive plasticity following cochlear implantation.
Main Methods:
- Examined pCREB and BDNF expression in animal models with sensorineural hearing loss and after long-term cochlear implant stimulation.
- Analyzed the activation of the MAPK signaling pathway in response to intracochlear electrical stimulation.
Main Results:
- Sensorineural hearing loss was associated with reduced expression of pCREB and BDNF.
- Long-term intracochlear electrical stimulation in deafened animals led to increased pCREB and BDNF expression in contralateral auditory cortical neurons compared to ipsilateral ones.
- Cochlear implantation induced changes accompanied by activation of the MAPK signaling pathway.
Conclusions:
- CREB and BDNF are critical modulators of synaptic plasticity, and their expression is altered in the auditory cortex following cochlear implantation.
- These findings identify potential molecular candidates involved in adaptive brain mechanisms during functional electrical stimulation by neural prosthetic devices.
- The study provides insights into the molecular underpinnings of auditory cortex adaptation to cochlear implants.
Related Concept Videos
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...
01:13The 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.