This paper presents a short selective tutorial on the processes in neurons and neural tissue, such as saltatory excitation transfer in myelinated axons, nonsynaptic propagation of excitation from one activated neuron to the nearest neighbors (ephaptic coupling), and their mathematical descriptions. All these processes are associated with charging the active axon membrane to a potential difference exceeding the threshold, due to currents in the extracellular and intracellular media, resulting in the initiation of action potentials. Also, the issues of control of the activity of nervous tissue in external microwave or ultrasonic fields are considered. It is shown that such an effect can be a result of the action potential activation threshold changing, caused by the forced redistribution of the unbounded transmembrane protein ion channels.