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mGluRs modulate neuronal firing in the auditory midbrain
1Department of Anatomy and Neurobiology, Northeastern Ohio Universities College of Medicine, 4209 State Route 44, Rootstown, OH 44272, USA.
Neuroscience Letters
|February 9, 2011
Summary
Metabotropic glutamate receptors (mGluRs) in the inferior colliculus (IC) modulate sound-evoked neuronal firing. Group I mGluR antagonists block sound-induced firing suppression, potentially linking to tinnitus perception.
Area of Science:
- Neuroscience
- Auditory System Physiology
- Glutamatergic Signaling
Background:
- Mechanisms of sound-evoked neuronal firing suppression in the auditory system remain unclear.
- The inferior colliculus (IC) is a key auditory processing center.
- Metabotropic glutamate receptors (mGluRs) are implicated in neuronal excitability.
Purpose of the Study:
- To investigate the role of mGluRs in sound-evoked neuronal firing suppression in the IC.
- To explore the potential link between IC neuronal activity and auditory perception phenomena.
Main Methods:
- Iontophoretic application of mGluR agonists and antagonists to IC neurons in awake mice.
- Recording neuronal firing rates in response to drug application and sound stimuli.
- Analyzing the effects of specific mGluR groups (I, II, III) on neuronal activity.
Main Results:
- Group I mGluR agonists increased firing in 52% of neurons; antagonists decreased firing in 51%.
- Group II mGluR antagonists increased firing rate in 48% of neurons; agonists had no effect.
- Group III mGluRs did not affect IC neuronal firing.
- Sound stimuli suppressed spontaneous firing in 70% of IC neurons, reversibly blocked by group I antagonists.
Conclusions:
- Group I mGluRs play a significant role in regulating neuronal firing in the IC.
- Group I mGluRs are crucial for mediating sound-evoked suppression of neuronal firing.
- This suppression mechanism may underlie perceptual phenomena like forward masking and residual inhibition, relevant to tinnitus.
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...
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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.