I believe the answer to your question is the synapse. "In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell."  Typically a synapse is the space between the axon and the dendrite. It is within the space that a neurotransmitter is released.  The neurotransmitter carries messages from one neuron to another.

There are two different kinds of synapses:

1. Chemical Synapse-a neurotransmitter is released to carry messages between neurons.
2. Electrical Synapse-are channels that are capable of passing electrical current.  " Electrical synapses are often found in neural systems that require the fastest possible response, such as defensive reflexes."