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?


1 Answer 1


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! ;)

  • $\begingroup$ Did he show that the diameter is the only factor? $\endgroup$
    – user24
    Jan 10, 2012 at 9:03
  • 1
    $\begingroup$ 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. $\endgroup$
    – Aleadam
    Jan 11, 2012 at 5:10
  • $\begingroup$ +1 for answer and making me laugh. Giant axons are giant, man! $\endgroup$
    – Poshpaws
    Jan 12, 2012 at 20:44

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