Final answer:
A neural circuit in which a single impulse is transmitted over and over is a reverberating circuit. It features neurons arranged in a loop that allows the signal to travel through a series of synaptic connections, with the last neuron re-exciting a previous one to sustain the circuit's activity.
Step-by-step explanation:
A neural circuit in which a single impulse is transmitted over and over is a reverberating circuit. In such circuits, the signal travels through a chain of neurons, each making excitatory synapses with the next neuron. After the last neuron in the circuit, there is often a neuron that sends an excitatory signal back to a previous neuron in the pathway to start the process again, therefore creating a loop that can continue to activate itself.
When a signal is transferred from one neuron to another, it typically travels from the axon terminal of the presynaptic neuron across the synaptic cleft, where neurotransmitters are released, to the dendrites of the postsynaptic neuron. The neurotransmitters released by synaptic end bulbs bind to receptors on the postsynaptic neuron, causing graded potentials that may summate to reach the threshold and initiate a new action potential in the postsynaptic neuron.