PSYC 2030 Lecture Notes - Lecture 14: Myelin
29 May 2018
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PSYC 2030 Lecture 14 Notes
Introduction
How Neurons Communicate
• In myelinated neurons, the action potential speeds up by hopping from the end of one
eli sausage to the et.
• The mind boggles when imagining this electrochemical process repeating up to 100 or
even 1000 times a second.
• But this is just the first of much astonishment.
• Each neuron is itself a miniature decision- making device performing complex
calculations as it receives signals from hundreds, even thousands, of other neurons.
• Most sigals ae eitato, soewhat like pushig a euo’s aeleato.
• Some are inhibitory, more like pushing its brake.
• If excitatory signals exceed the inhibitory signals by a minimum intensity, or threshold,
the combined signals trigger an action potential.
• Think of it this way: If the excitatory party animals outvote the inhibitory party poopers,
the pat’s o.
• The action potential then travels down the axon, which branches into junctions with
hudeds o thousads of othe euos o with the od’s usles ad glads.
• Increasing the level of stimulation above the threshold will not increase the neural
ipulse’s itesit.
• The euo’s eatio is a all- or- none response
• Like gus, euos eithe fie o the do’t.
• How, then, do we detect the intensity of a stimulus?
• How do we distinguish a gentle touch from a big hug?
• A strong stimulus can trigger more neurons to fire and to f ire more often.
• But it does not affect the atio potetial’s stegth o speed.
• “ueezig a tigge hade wo’t ake a ullet go faste.
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