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Postsynaptic Recordings at Afferent Dendrites Contacting Cochlear Inner Hair Cells: Monitoring Multivesicular Release at a Ribbon Synapse
Published on: February 10, 2011
Hair cell synaptic ribbons are essential for synchronous auditory signalling
Darina Khimich1, Régis Nouvian, Rémy Pujol
1Department of Otolaryngology and Center for Molecular Physiology of the Brain, University of Goettingen, 37099 Goettingen, Germany.
Nature
|April 15, 2005
Summary
Presynaptic Bassoon protein anchors synaptic ribbons in inner hair cells (IHCs), crucial for auditory signaling. Impaired ribbon anchoring disrupts vesicle release and synchronous neural activation, essential for normal hearing.
Area of Science:
- Neuroscience
- Auditory system research
- Cell biology
Background:
- Auditory signaling depends on synaptic transmission at inner hair cell (IHC) ribbon synapses.
- The precise function of presynaptic ribbons in IHCs remains largely undetermined.
Purpose of the Study:
- To investigate the role of the presynaptic scaffolding protein Bassoon in anchoring synaptic ribbons at IHCs.
- To elucidate the functional consequences of impaired ribbon anchoring on auditory neurotransmission.
Main Methods:
- Utilized mouse mutants lacking functional Bassoon to study ribbon synapse structure and function.
- Recorded exocytic IHC capacitance changes and sound-evoked spiral ganglion neuron activation.
- Analyzed vesicle pools, exocytosis, and endocytic membrane retrieval in IHCs.
Main Results:
- Impaired anchoring of synaptic ribbons in Bassoon-deficient mice was observed.
- Reduced readily releasable vesicle pools and impaired synchronous auditory signaling were evident.
- Hair cell exocytosis and spiral ganglion neuron activation correlated with anchored ribbon numbers.
Conclusions:
- Ribbon anchoring by Bassoon is critical for maintaining the readily releasable vesicle pool at IHC synapses.
- Ribbon-dependent synchronous release is essential for normal auditory signaling and hearing.
- While sustained exocytosis and endocytosis are intact, ribbon deficiency leads to membrane profile accumulation.
Related Concept Videos
01:12Synaptic Signaling
Neurons communicate at synapses, or junctions, to excite or inhibit the activity of other neurons or target cells, such as muscles. Synapses may be chemical or electrical.
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.
01:13The 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.
01:09Synaptic Signaling
Neurons communicate at synapses, or junctions, to excite or inhibit the activity of other neurons or target cells, such as muscles. Synapses may be chemical or electrical.
Most synapses are chemical, meaning an electrical impulse or action potential spurs the release of chemical messengers called neurotransmitters. The neuron sending the signal is called the presynaptic neuron, and the neuron receiving the signal is the postsynaptic neuron.
The presynaptic neuron fires an action potential that...
Most synapses are chemical, meaning an electrical impulse or action potential spurs the release of chemical messengers called neurotransmitters. The neuron sending the signal is called the presynaptic neuron, and the neuron receiving the signal is the postsynaptic neuron.
The presynaptic neuron fires an action potential that...
01:28Electrical Synapses
Electrical synapses found in all nervous systems play important and unique roles. In these synapses, the presynaptic and postsynaptic membranes are very close together (3.5 nm) and are actually physically connected by channel proteins forming gap junctions.
Gap junctions allow the current to pass directly from one cell to the next. In contrast, in the chemical synapse, the neurotransmitters carry the information through the synaptic cleft from one neuron to the next. They consist of two...
Gap junctions allow the current to pass directly from one cell to the next. In contrast, in the chemical synapse, the neurotransmitters carry the information through the synaptic cleft from one neuron to the next. They consist of two...
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...