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Conduction of impulses in myelinated axons has been studied by a new method of computer simulation. The contributions of nodal and internodal characteristics and parameters were examined. Surprisingly, the conduction velocity, theta, was found to be quite insensitive to the nodal area or the exact description of its excitable processes. The conduction(More)
It has been argued theoretically and confirmed experimentally that conduction velocity (theta) should be proportional to nerve fibre diameter for myelinated fibre tracts, such as normal peripheral nerve, exhibiting 'structural' similarity'. In some axons, however, the nodes of Ranvier are more closely spaced than in normal peripheral nerve. Analytic(More)
Clinical and laboratory observations both suggest that it may be possible for action potentials to traverse, in a continuous manner and without interruption, demyelinated zones along some axons. This continuous mode of conduction requires the presence of sufficient numbers of sodium channels in the demyelinated region. One of the factors which will tend to(More)
The properties of constancy models based on the proportionality rule of von Kries are examined in a series of simplified examples. It is found that the breadth of receptor-sensitivity functions causes metamerism, thwarting color constancy. Overlap of these functions limits the accuracy of von Kries adaptation for a more subtle reason: it causes nonzero(More)
Necessary and sufficient spectral conditions are presented for Von Kries chromatic adaptation to give color constancy. Von-Kries-invariant reflectance spectra are computed for illuminant spectral power distributions that are arbitrary linear combinations of the first three daylight phases. Experiments are suggested to test models of color constancy using(More)