RECONSTRUCTION OF MYELINATED NERVE TRACT ACTION POTENTIALS - AN ARITHMETIC METHOD

Compound action potentials from central nerve tracts or peripheral nerves may be constructed from corresponding fiber diameter histograms by a new direct method. The ordinate for each fiber diameter group is determined by the product of the number of fibers and the cube of the mean diameter (ND3), and the abscissa, by the position of the mean group diameter on a scale proportional to the reciprocal of fiber diameters ( 1 D). The time scale is derived from a prominent component, conveniently the first spike peak, of the corresponding recorded compound action potential. Direct comparison with published reconstructions from peripheral nerves is made, using the original morphologic data. Reconstruction for a central tract, the cat optic nerve, is also shown. The method avoids the cumbersome geometry of the classical approach, and is especially convenient for the correlated anatomic and physiologic analysis of central tracts where accurate measurement of conduction distances is difficult, and where postsynaptic activity may distort the record of tract potential. © 1968.