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action potential - neuroscientific Achilles heel

GREGORY C.O'KELLY gokelly at delphi.com
Mon May 9 18:28:03 EST 1994


People harp on me for holding that ion currents don't act like electrical currents, for believing that whereas all electricity is currrent, not all current is electricity.  I try to make it clear with an analogy to water being composed of ions, to water'
s flow not involving the equations of electrical circuitry even if its currents involve the movement of charge.  The essay "Action Potentials - " is the first in a trilogy of essays.  In the third, "Biology and Electricity: an Historical Perspective", I 
discuss the limits of metaphor with regard to the electron as a particle, and relate it to and contrast the scientific paradigms of Newtonian classical mechanics and modern day field theory or electrodynamics.  Herein with regard to the issue of action p
otentials is an example of those limits.  Dr. Koester tries to appeal to an equation for work W = f x d when discussing electricity.  In the examples he shows are a graph of  f vs d for a constant f and d, with the area under the curve darkened as work; 
 and he shows a hand moving an electrically charged tip on a wand from one plate to another, the two being oppositely charged.  He talks of force, and for him this force is the electrostatic force which must be resisted for the movement.  But if this for
ce is electrical then the equation to use is W = C x Vsquared/2 which is the area for the curve under the equation relating capacitance and voltage.  Voltage is called ELECTROMOTIVE FORCE, but it is not a force, and already contains the value of d in its
 unit of measure, i.e., the work needed to move a coulomb one meter against a force of one Newton.  Dr. Koester's metaphor has gotten the better of him;  he has removed the issue from the area of the equations of electricity which do not support his case
 even if there is such a thing as electrical ion current, and he as couched the issue in terms of classical mechanics where a force acts over a distance.
	Classical mechanics, flowing from Newton, treated only one of the four fundamental forces of nature, gravity.  It could not explain light, magnetism, electricity, chemistry (the periodic table of the elements in particular).  Classical mechanics is inad
equate for describing with equations electricity, though it can still provide powerful metphors if we think of the electron has a particle.  But Feynman, Schwinger, and Tomonaga got a Nobel in 1965 for their work in the late 40's for showing the electron
-as-particle view to be totally inadequate.  Not coincidently this was the time when the theory of action potentials was being formulated which was awarded a Nobel in 1963.



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