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Biomedical subjects

L Goldman

Publications and source records attributed to L Goldman.

At least 559 records · Page 31Linked to original sources
PubMed1968

Computation of impulse conduction in myelinated fibers; theoretical basis of the velocity-diameter relation.

For myelinated fibers, it is experimentally well established that spike conduction velocity is proportional to fiber diameter. However no really satisfactory theoretical treatment has been proposed. To treat this problem a theoretical axon was described consisting of lengths of passive leaky cable (internode) regularly interrupted by short isopotential patches of excitable membrane (node). The nodal membrane was assumed to obey the Frankenhaeuser-Huxley equations. The explicit diameter dependencies of the various parameters were incorporated into the equations. The fiber diameter to axon diameter ratio was taken to be constant, and the internode length was taken to be proportional to the fiber diameter. Both these conditions reflect the situation that exists in real, experimental fibers. Dimensional analysis shows that these anatomical conditions are equivalent to Rushton's (1951) assumption of corresponding states. Hence, conduction velocity will be proportional to fiber diameter, in complete agreement with the experimental findings. Digital computer solutions of these equations were made in order to compute a set of actual velocities. Computations made with constant internode length or constant myelin thickness (i.e., nonconstant fiber diameter to axon diameter ratio) did not show linearity of the velocity-diameter relation.

Action Potentials↗
PubMed1967

Giant axon of Myxicola: some membrane properties as observed under voltage clamp.

A new space-voltage clamped giant (500 to 900 microns) axon preparation is described (Myxicola infundibulum). Normal value for resting and action potentials are 71 and 89 millivolts, respectively. This preparation under voltage clamp exhibits relations between current and voltage like those described for the squid axon. The early inward current component is reduced in a solution with low sodium concentration. This preparation, then, acts in all its essential features like the squid giant axon. Myxicola, however, can be made available the year around and should prove to be an extremely useful preparation for the study of excitable membranes.

Animals↗