John H. <johnh at faraway.xxx> wrote:
> At what time scale does the nervous system operate?
Well, that's still an open question isn't it? There are 2 schools of
thought (grossly oversimplifying), one that says timing is exquisitely
important, and the relative timing of 2 spikes might encode information down
to the 100 microsecond range, and the other that says that only the average
firing rate, averaged over a certain time window and over neighboring
spikes, is what matters.
If you look at the book "Spikes" by Bialek and others, they take the
position that it's half-way between the time code and the rate code, i.e.
you have about 1 spike per relevant time-scale. Say you listen to speech,
and extract the spectral envelope which changes (phonemic rate) _about_ every
30 msec. If the primary auditory cortical neurons are the ones in charge of
extracting spectral envelope, you will find as a correlate that primary
auditory neurons fires at about a rate of 30 Hz...
So the answer, as ever, is "it depends".
For timing issues, look at the paper on
http://homepage.mac.com/cariani/CarianiWebsite/Publications.html
called "As if time really mattered"
Didier
--
Didier A Depireux ddepi001 at umaryland.edudidier at isr.umd.edu
685 W.Baltimore Str http://neurobiology.umaryland.edu/depireux.htm
Anatomy and Neurobiology Phone: 410-706-1272 (off)
University of Maryland -1273 (lab)
Baltimore MD 21201 USA Fax: 1-410-706-2512
