As batteries generate electricity from chemical events, so the neuron's electrical impulse arises from chemical events. Neural Messages 3. Describe how nerve cells communicate and discuss the impact of neurotransmitters and drugs on human behavior. When electrical impulses reach the axon terminal , they stimulate the release of chemical messengers, called neurotransmitters , which cross the synapse, the junction between neurons. After these molecules cross the tiny synaptic gap between neurons, they bind to receptor sites on neighboring neurons, thus passing on their excitatory or inhibitory messages.
Different neurotransmitters have different effects on behavior and emotion.
For example, release of acetylcholine, the neurotransmitter found at every junction between a motor neuron and a muscle, causes the muscle to contract. When the brain is flooded with opiate drugs such as heroin and morphine, however, it may stop producing its own natural opiates, and withdrawal of these drugs may result in pain until the brain resumes production of its natural opiates. Researchers have used this information about neurotransmitters in the brain in their efforts to create therapeutic drugs, such as those used to alleviate depression. Some drugs mimic a natural neurotransmitter, while others block its effects. Still others work by hampering the neurotransmitter's natural breakdown or its reabsorption.