Section2-1-2 - e.g., antibiotics Congenital (genetic)...

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2/7/12 1 Terminal T T T T T T T T Vesicles containing Neurotransmitter Receptor Action Potential Depolarization ++ ++ ++ ++ Voltage-gated calcium channels Synaptic cleft or gap Excitatory post-synaptic potential ( EPSP ) Channels • Channels allow ions through the membrane • Are Proteins embedded in the lipid (fat) membrane • Are classiFed by – What opens (gates) them – What ions they let through • An action potential starts with voltage-gated Na + channels open Voltage -gated vs Ligand -gated channels Ligand-gated = Neurotransmitter Receptor Endolymph (±uid in cochlear duct) has very high K + concentration But…“Receptor potential” results in release of NT: K + comes in (depolarization), Ca ++ comes in (V-gated Ca ++ channels), NT release Auditory nerve Note: different than neurons High external K + no action potential Deafness: Normal Damaged Hair cells don’t grow back (in mammals) Major cause: Loss of hair cells Presbycusis: age-related Noise-induced Some drugs
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Unformatted text preview: e.g., antibiotics Congenital (genetic) Tonotopic (frequency map) Organization The Cochlear Implant Coil of electrodes placed inside cochlea • ²or most deafness, the Hair Cells are damaged, but the auditory nerve Fbers are still there! • Brain doesn’t care how auditory nerve is stimulated, but if it is, you will hear a sound (doctrine of speciFc nerve energies). 2/7/12 2 Different electrodes can stimulate different places, so different frequencies are perceived (Tonotopic organization: labeled line coding). Electrode array in cochlea Receiver under skin with wire to implant Transmitter worn outside provides commands to activate electrodes Part implanted in patient Implanted in cochlea Placed under the skin Part worn outside The Cochlear Implant • VERY successful • Many patients can go from profound deafness to talking on the telephone! Simulation...
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This note was uploaded on 04/09/2012 for the course EXP 3202 taught by Professor Staff during the Spring '12 term at Florida State College.

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Section2-1-2 - e.g., antibiotics Congenital (genetic)...

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