What role do neurotransmitters play in neuronal communication?

Neurotransmitters play a crucial role in neuronal communication by facilitating the transmission of signals between neurons. When an electrical impulse, or action potential, reaches the end of a neuron at the synapse, neurotransmitters are released into the synaptic cleft. These chemical messengers then bind to receptor sites on the postsynaptic neuron, leading to a response that can either initiate a new action potential or inhibit one.

This bonding process essentially 'restarts' the signal in the next neuron, allowing for the propagation of the nerve impulse throughout the nervous system. In this way, neurotransmitters are essential for communication between neurons, enabling the coordinated function of neural circuits involved in everything from muscle contraction to sensory perception and cognitive processes.

The other options describe processes that do not accurately represent the function of neurotransmitters. They do not send electrical impulses themselves, nor do they create structures such as myelin sheaths, which are important for the insulation of axons. While neurotransmitters do influence ion flow, particularly in the postsynaptic neuron, their primary role is to facilitate the transfer of signals through synapses, making 'restarting impulses in the next neuron' the most accurate description of their function.