[Neuroscience] Re: Neuronal activity in the brain
(by m.kirkcaldie from removethis.unsw.edu.au)
Sat Oct 21 19:41:03 EST 2006
In article <ehdkh3$are$1 from mailhub227.itcs.purdue.edu>,
"Fijoy George" <tofijoy from yahoo.co.in> wrote:
> Hi all,
> Would someone be able to help me with the following question?
> When we look at the neuronal activation areas in Functional Magnetic
> Resonance Images obtained from various experiments, we see that in each
> area, the activity is most intense at the center and slowly declines towards
> the boundary. Now, suppose we were to actually measure the neuronal currents
> in the activation areas. Will the current amplitudes follow the same
> pattern? That is, will the current amplitudes be highest near the center of
> the area, and smoothly decline toward the boundary?
> Thank you very much
Fairly unlikely, in my estimate. The nearest correlate to fMRI signal I
know of is firing rate in neurons, but the decrease at the edges of the
fMRI signal is likely to be a combination of measurement artifact
(limited resolution of the technique) and the anatomy of the blood
vessels - in particular, anastomoses between vessels, spreading
increased blood flow around the activated area. I'm not exactly sure
what you mean by "neuronal currents" - firing rates? Evoked
potentials? More info would allow a better answer.
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