 Dear students, in this module we shall discuss the methods of transmission of signal in a single neuron. A nerve cell receives inputs through tendrites or membranes of its soma. The soma or cell body integrates the messages from all inputs and determines if the response is to be propagated through active processes that is through the production of action potential or through passive processes that is through graded, electrotonically conducted messages. The information received at the receptor site produces a stimulus-generated local depolarization. This local depolarization can spread through two methods that is passive-electrotonic conduction that happens in non-spiking local circuit neurons while the active regenerative action potentials are generated in those neurons which have voltage-gated ion channels. First, we will talk about non-spiking neurons that do not generate action potentials. We will talk about local circuit neurons. These neurons are usually small in size and they lack voltage-gated ion channels. They have only resting potassium channels. These resting potassium channels do not generate action potentials because of these. To generate action potentials, actually voltage-gated ion channels should be generated. A cell that does not have these cannot generate action potentials. So, in these neurons, conductance depends on their passive electrical properties which include the capacitance and resistance. These cable properties make the exon comparable to an electrical wire. These cable properties affect the speed and distance of transmission of electrical signals in the neurons. Cable properties have some effects. For example, if a current passes through an electrical wire, some electrical current is lost. There is a loss. Similarly, these neurons that are working because of passive electrical properties have a little loss or decay in the current. This decay happens because of the resistance of the cytoplasm that it presents to the flow of ionic current. The second reason is that if the external membrane does not have insulation because the layer of myelin does not exist, then because of this, potassium ions, i.e., the current, outflows which causes the current loss. These local circuit neurons which are only a few millimeters in length can only conduct signals through graded potentials. And these graded potentials are transferred in passive electronic way from the exon terminal to the next neurons. These do not take the aid of action potentials. In all this process, the amplitude of signal is attenuated. This signal becomes weak as it reaches here. However, signals are still large enough at the exon terminals that they can be released by neurotransmitters. Compared to this, the neurons that generate action potentials have functional voltage-gated ion channels. And they have active electrical properties. These neurons carry electrical signals without decrement by producing regenerative action potentials. Such neurons often have longer exons and they can transmit signals to long distances.