Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: Did you ever watch a relay race? After the first runner races, he or she passes the baton to the next runner, who takes over. Neurons are a little like relay runners. Instead of a baton, they pass neurotransmitters to the next neuron. Examples of neurotransmitters are chemicals such as serotonin, dopamine, and adrenaline. Answer: neurotransmitters
A:
What do neurons pass to the next neuron?