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Functional Imaging of Auditory Cortex in Adult Cats using High-field fMRI
Published on: February 19, 2014
Age-related tonotopic map plasticity in the central auditory pathways
1Department of Otolaryngology, The Hospital for Sick Children, and University of Toronto, Canada. rvh@sickkids.on.ca
Scandinavian Audiology. Supplementum
|June 21, 2001
Summary
Neonatal cochlear lesions cause significant auditory midbrain plasticity and map reorganization in chinchillas. This developmental plasticity is reduced in adult animals, impacting auditory system function.
Area of Science:
- Neuroscience
- Auditory System Research
- Developmental Plasticity
Background:
- Inner hair cell lesions in the cochlea lead to auditory system deafferentation.
- Auditory system maps in the midbrain (inferior colliculus) change following deafferentation.
Purpose of the Study:
- To investigate the impact of neonatal versus adult cochlear lesions on auditory midbrain tonotopic map reorganization.
- To compare the extent of plasticity in the developing versus mature auditory system.
Main Methods:
- Inducing cochlear lesions in neonatal and adult chinchillas.
- Analyzing changes in cochleotopic maps based on single-unit response characteristic frequencies in the central nucleus of the inferior colliculus.
Main Results:
- Neonatal cochlear lesions resulted in more extensive reorganization of frequency maps compared to adult lesions.
- Neonatal lesions led to an over-representation of frequencies bordering the lesion site, unlike in adults.
- Significant plasticity was observed in the auditory midbrain during early postnatal development.
Conclusions:
- The auditory midbrain exhibits substantial plasticity during early development, which diminishes in adulthood.
- Early-life deafferentation drives significant map re-wiring in the developing auditory system.
- A conceptual model for frequency map re-wiring in the auditory midbrain is proposed.
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.
01:15Auditory 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.
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01:01Neuroplasticity
Neuroplasticity reflects the brain's remarkable capacity to adapt and evolve, responding dynamically to learning, experiences, or injury by reorganizing its neural circuitry. This reorganization involves creating new neural connections and refining old ones through a series of biological processes that contribute to the brain's lifelong development and adaptability.
01:21Perceiving Loudness, Pitch, and Location
The human brain perceives pitch through two primary mechanisms reflected in place theory and frequency theory. Each mechanism describes how sound waves are interpreted as specific pitches by the brain, offering insights into the intricate processes of auditory perception.
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...
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