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The conduction velocity of the squid giant axon can reach 30 m/s. Is there any known example of an even faster conducting unmyelinated axons?

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The conductance velocity in the unmyelinated axon has been calculated and measured to be proportional to the square root of the axon diameter (see for example: Rushton, 1951). Since the giant axon is, well, giant, it conducts much faster than others. AFAIK, all other large neurons studied are myelinated. Maybe try to find bigger squids! ;)

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Did he show that the diameter is the only factor? –  user24 Jan 10 '12 at 9:03
No, that's just one factor, but thought to be more variable than others, such as membrane capacitance or cytoplasm resistance, that are less variable among different cell types. –  Aleadam Jan 11 '12 at 5:10
+1 for answer and making me laugh. Giant axons are giant, man! –  Poshpaws Jan 12 '12 at 20:44

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