## Info

As a simple example, assume a dendrite of diameter D stretching from x = 0 to x = x. At x = 0, a voltage source holds vm(0) at Vm0 V. vm(x) = 0, Ie - 0. Thus it is clear that B = K = 0, and A = Vm0. The dc voltage along the dendrite decays exponentially as x ^ x.

The space constant, X, of a dendrite is an important parameter because it is a measure of the steady-state electrotonic spread of epsps and ipsps. It can be shown that the bulk parameters of the UM and the axoplasm are related to X by

where D is the diameter of the dendrite in cm, GM is the leakage conductivity of the membrane in S/cm2, and pi is the axoplasm resistivity in ohm cm. Note that X increases with the square root of the diameter of the dendrite, other bulk parameters being held constant.

The rate of spread of a transient voltage induced on a passive dendrite is inversely proportional to the product, (ro + ri)cm (Kandel et al., 1991). If one assumes that ri > ro, and expresses (ri cm)-1 in terms of the bulk parameters of the membrane, then

where D is the dendrite diameter in cm, pi is the axoplasm resistivity in ohm cm, and Cm is the bulk membrane capacitance in F/cm2. Thus, the larger the dendrite diameter, the faster the passive spread velocity.

Was this article helpful?

This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.

Get My Free Ebook

## Post a comment