Final answer:
A neurotransmitter is a chemical messenger within the brain that activates specific cells. It helps transmit signals between neurons and is involved in various functions of the nervous system.
Step-by-step explanation:
A neurotransmitter is a chemical messenger within the brain that activates specific cells. It is responsible for transmitting signals between nerve cells, or neurons, in the brain. Neurotransmitters play a crucial role in various functions of the nervous system, such as regulating mood, controlling movement, and facilitating communication between neurons. Examples of neurotransmitters include serotonin, dopamine, and acetylcholine.
Learn more about neurotransmitters