PSY270H1 Lecture Notes - Lecture 2: Myelin, Silver Nitrate, Resting Potential
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PSY270H1 Full Course Notes
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19th century: believed brain was 1 continuous network. Staining of neurons- not high resolution couldn"t distinguish b/w individual neurons. Believed that brain was a connected net of connections. Stained neurons w/ silver nitrate stained 1% of neurons (saw individual neurons) Shows that neurons don"t all connect- grouped in certain pathways. Drew neurons & noticed that neurons don"t physically touch each other. Communication is sending messages b/w the gap. Composed of soma, dendrites, axons and myelin sheaths. Axons are covered in myelin sheath- faster & more efficient communication. Terminal buttons: where two neurons have their synapse (communicate) All or nothing principle: they either happen or they don"t, action potentials do not vary in degree all action potentials are exactly the same. Creates different signals (strong & weak) by varying firing frequencies: strong signal (ex. loud noise)- rapid, frequent firing, weak signal (ex. soft whispers) slower, less frequent firing. Resting potential depolarize surpass threshold repolarization .
