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Synaptic Transmission at the Ribbon Synapses of the Eye and Ear

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Air date: Monday, November 1, 2010, 12:00:00 PM
Time displayed is Eastern Time, Washington DC Local
Views: Total views: 316 * This only includes stats from October 2011 and forward.
Category: Neuroscience
Runtime: 01:10:47
Description: Neuroscience Seminar Series

Sensory information is conveyed by neurons specialized to faithfully transmit large amounts of information at high rates. A key event in synaptic transmission is the release of neurotransmitter via vesicle fusion at synaptic terminals. Direct studies of synaptic terminals have been hampered by technical constraints. However, using high time resolution patch-clamp and membrane capacitance measurements, Dr. Von Gersdorff Lab has studied the kinetics of vesicle fusion (exocytosis) and subsequent membrane retrieval (endocytosis) in single, live synaptic terminals from bipolar cells of the goldfish retina and from hair cells of the frog amphibian papilla. These cells have compact ribbon-type active zones that contain a large pool of releasable vesicles suitable for the transfer of high bandwidths of information. Following short depolarizations, a fast form of endocytosis can be observed, indicating that synaptic vesicle membrane is quickly re-internalized after vesicle fusion. They are presently investigating mechanisms for short-term synaptic plasticity at reciprocal synapses in retinal slices, and multivesicular release at the hair cell synapse using capacitance measurements together with paired recordings of hair cells and their afferent fibers.

To study conventional active zone synapses, the lab has been examining the calyx of Held nerve terminal, a pivotal element in the auditory brainstem circuitry that computes sound source localization. Precise timing of action potential discharges is essential for accomplishing this task. Nevertheless, the mechanisms that modulate and preserve the timing of spikes are poorly understood. Dr. Von Gersdorff Lab is studying these mechanisms and short-term forms of plasticity at this synapse. The large size of the calyx terminal allows them to patch-clamp the terminal and the postsynaptic cell simultaneously, and thus to measure Ca2+ currents, presynaptic capacitance changes, and glutamate release. This direct access to the terminal allows the lab to study the kinetics of synaptic vesicle exocytosis and endocytosis, neurotransmitter reuptake, and the modulation of neuronal output patterns by presynaptic receptors and the Na+/K+-ATPase pump. Presently, the lab is focused on developmental changes that fine-tune auditory synapses for high frequency firing, and developing techniques for imaging the fast dynamics of Ca2+ and Na+ ions in the nerve terminal and axonal afferent fibers.
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NLM Title: Synaptic transmission at the ribbon synapses of the eye and ear / Henrique von Gersdorff.
Author: Von Gersdorff, Henrique.
National Institutes of Health (U.S.)
Publisher:
Abstract: (CIT): Neuroscience Seminar Series Sensory information is conveyed by neurons specialized to faithfully transmit large amounts of information at high rates. A key event in synaptic transmission is the release of neurotransmitter via vesicle fusion at synaptic terminals. Direct studies of synaptic terminals have been hampered by technical constraints. However, using high time resolution patch-clamp and membrane capacitance measurements, Dr. Von Gersdorff Lab has studied the kinetics of vesicle fusion (exocytosis) and subsequent membrane retrieval (endocytosis) in single, live synaptic terminals from bipolar cells of the goldfish retina and from hair cells of the frog amphibian papilla. These cells have compact ribbon-type active zones that contain a large pool of releasable vesicles suitable for the transfer of high bandwidths of information. Following short depolarizations, a fast form of endocytosis can be observed, indicating that synaptic vesicle membrane is quickly re-internalized after vesicle fusion. They are presently investigating mechanisms for short-term synaptic plasticity at reciprocal synapses in retinal slices, and multivesicular release at the hair cell synapse using capacitance measurements together with paired recordings of hair cells and their afferent fibers. To study conventional active zone synapses, the lab has been examining the calyx of Held nerve terminal, a pivotal element in the auditory brainstem circuitry that computes sound source localization. Precise timing of action potential discharges is essential for accomplishing this task. Nevertheless, the mechanisms that modulate and preserve the timing of spikes are poorly understood. Dr. Von Gersdorff Lab is studying these mechanisms and short-term forms of plasticity at this synapse. The large size of the calyx terminal allows them to patch-clamp the terminal and the postsynaptic cell simultaneously, and thus to measure Ca2+ currents, presynaptic capacitance changes, and glutamate release. This direct access to the terminal allows the lab to study the kinetics of synaptic vesicle exocytosis and endocytosis, neurotransmitter reuptake, and the modulation of neuronal output patterns by presynaptic receptors and the Na+/K+-ATPase pump. Presently, the lab is focused on developmental changes that fine-tune auditory synapses for high frequency firing, and developing techniques for imaging the fast dynamics of Ca2+ and Na+ ions in the nerve terminal and axonal afferent fibers.
Subjects: Hair Cells, Auditory--physiology
Retinal Rod Photoreceptor Cells--physiology
Synaptic Transmission--physiology
Publication Types: Lecture
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NLM Classification: WW 270
NLM ID: 101549231
CIT Live ID: 9738
Permanent link: https://videocast.nih.gov/launch.asp?16240

 

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