Question

What is the definition of the length constant? What does the length constant tell you in terms of the electrical signal? Neurons are designed to maximize the length constant – why? What aspect of a neuron’s cable properties are manipulated to maximize the length constant? How are neurons modified (i.e. what is done to the structure of the neuron) to maximize the length constant?

Answer 1

In neurobiology, the length constant (?) is a mathematical constant used to quantify the distance that a graded electric potential will travel along a neurite via passive electrical conduction.

In terms of electrical signal,The greater the value of the length constant, the farther the potential will travel.

A large length constant can contribute to spatial summation—the electrical addition of one potential with potentials from adjacent areas of the cell.

The length constant increases with increasing radius of the neuron..

The length constant is a way to characterize how far passive current flow spreads before it leaks out of the axon, with leakier axons having shorter length constants.

To improve the passive flow of current along an axon, the resistance of the plasma membrane should be as high as possible and the resistances of the axoplasm and extracellular medium should be low.