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[Neuroscience] Re: Frequencies of impulses in brain

Matthew Kirkcaldie via neur-sci%40net.bio.net (by m.kirkcaldie At removethis.unsw.edu.au)
Sat Dec 9 22:55:41 EST 2006


In article <1165701310.527446.233760 At n67g2000cwd.googlegroups.com>,
 "Marcin" <marcin.gierlicki At gmail.com> wrote:

> Hi,
> 
> I'm looking for informations about signals frequencies in brain
> depending on area of it. For example range of frequencies for area
> responsible for hearing or motor function. I need this information to
> my master thesis about recordin extracellular signals from neuronal
> cells.
> Can someone help ?
> 
> Kind of animal dosen't matter ;)
> 
> Thanks,
> Marcin

Maximum spike rate in neurons can be up to 2kHz - I believe there are 
phase-locked responses in cochlear afferents about this fast.

In cortex, 500-1000 spikes per second is the upper limit.  Almost never 
see 2 action potentials close than 1ms apart, aside maybe from burst 
firing in a basket cell.

In cortical extracellular recording, we typically use bandpass filtering 
to include, say, 300Hz - 10kHz, and would generally sample at 
10kHz-20kHz depending on specific requirements (and yes, we know about 
Nyquist limits!).  Including lower frequencies causes a lot of baseline 
shifts in potential to interfere with spike discrimination.  Sadly the 
baseline shifts are probably very important to cortical function, we 
just don't know how!

      Cheers, MK.


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