To : tvaughan at athena.mit.edu
Stimulation of neurones
I had the same problem as you, I couldn't find anything anywhere
about the amount of current or voltage required to stimulate neurons.
I look everywhere, infact I found the very first article descriping the
technique of focal stimulation :
Coombs JR, Eccles JC, Fatt P, (1955)
The specific ionic conductances and their ionic movements across the
motorneuronal membrane that produce the inhibitory post-synaptic
potential. J. Physiol (Lond) 130:326-373
The reference is used in B. Hille "Ionic channels of excitable
membranes"
Coombs et al used a double-electrode, one line for recording and one for
stimulation. The normal way today (if you want to do intracellular
recordings) is to have two separate electrodes.
What you need to do stimulation in hairy skin is a constant current
source driven by a huge potential source. I built one for use in in
vitro measurements of enteric neurones of the porcine small intestine.
The device is working very good and it is delivering currents in the
range 0.1-10 mA and in timeranges from 0.1-2 ms. It is driven by 32 9V
batteries = 288 V. This will in some circumstances not be a high enough
voltage.
So you need a CONSTANT CURRENT SOURCE, all electronic freaks know how to
built one.
MS Lars Thomsen
The Royal Veterinary & Agricultural University
Copenhagen Denmark
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