IUBio

Refractory Period

William Calvin wcalvin at hardy.u.washington.edu
Wed Apr 29 14:17:31 EST 1992


rowe at pender.ee.upenn.edu (Mickey Rowe) writes:

>Whoops, I forgot something else that I wanted to add.

>In article <75178 at netnews.upenn.edu> pedro at mulab.physiol.upenn.edu
>     (maldonado) writes:

>>In physiological (real) conditions, the highest rate are only up to
>>1Khz.

>While this is a good rule of thumb, there are some cells that are
>known to be a bit faster.  You might want to look into Renshaw Cells
>(in mammalian spinal cord).  I think that they can respond at rates
>one or two magnitudes higher.

WRONG.  1000 spikes/second is an approximate upper limit, though I've
routinely seen neurons in external cuneate with 0.8 msec interspike
intervals -- but only when firing in doublets (that's 1300 Hz
instantaneous rate).  Renshaw cells can fire a bit faster than 1000 Hz but
soon slow down.

The more appropriate figure for an upper limit is probably down around 200
spikes/sec -- and it varies, even among pyramidal track neurons (the
smaller ones have a lower upper limit).  
    William H. Calvin   WCalvin at U.Washington.edu
    University of Washington  NJ-15
    Seattle, Washington 98195 FAX:1-206-720-1989



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