NEU258_Lecture11_Audition2 notes

NEU258_Lecture11_Audition2 notes - Lecture 11 Audition II...

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Lecture 11... Audio recording started: 11:02 AM Thursday, October 18, 2012 Auditory transduction The trick of hearing deals with the cilia (of hair cells) and how they are bent Hair Cell (cross-section) - See Diagram 1 Long one is the kinocilium Bottom of hair cell is located at the bottom of the organ of Corgi Everything depends on the bending of hair cells In the cross section we would see 3 different cilia Has cilia sticking out of the top On the basilar membrane the are rows of hair cells - outer rows - on a given hair cell, there are also rows of cilia Output from the brain to the hair cells tends to be dominant in modulating the cell Each inner hair cell (about 10 inner hair cells synapsing on a single fiber) - 10 are needed to depolarize/sent signals onto the postsynaptic neuron (about a 10:1 ratio) Sounds of given frequencies and loudness can kill hair cells 95% of output form the brain comes from inner hair cells Why does the bending of the cilia lead to a change in the electrical inductance within the cell? A channel that would normally let in potassium (cell would become more positive inside and more depolarized - eventually activating the auditory nerves/spiral ganglion neurons) There is a springy door which is normally closed (on the receptor) - positive charge cannot flow into the hair cell when it is closed There is also a similar receptor on the longer cilia The doors of the receptors are connected together by tip links Bending in one direction (rightwards) - move the doors apart (tension opens up doors allowing ions to flow in); hence, no ions can flow in) It is a mechanically-gated channel Bending in the other direction (leftwards) - moves the doors closer (compression of tip-links closed doors; he If right one moves down - it becomes a lot closer to the other gate (tension is removed and the system becomes less sensitive to vibrations) Movement further away makes tension higher and make the door more likely to open - very sensitive to changes in position.
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  • Fall '11
  • Graziano
  • hair cell, hair cells, cochlear nucleus

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