Neuronal Growth Cone Guidance by Physiological DC Electric Fields

Neurons exist within a complex milieu, in which they are exposed to many factors that affect their growth, survival, and function. These factors can be grouped into three general categories: chemical (growth factors, neurotransmitters, or adhesion molecules, which can be either soluble or substratum bound), physical (contours of the three-dimensional space surrounding the cell), and electrical (standing extracellular voltage gradients). During development and repair, neurons use these environmental factors to guide the tips of growing axons, called growth cones, to appropriate targets (e.g., another neuron or a.