Are you getting ready to take the AP® Psychology exam? Are you nervous about keeping all those pesky neurotransmitters straight? Have no fear, because the ultimate AP® Psych guide to neurotransmitters is here.

First Things First: What are Neurotransmitters?

A neurotransmitter is a chemical messenger inside the body. Neurotransmitters carry messages between neurons. They are produced only in the neurons, and because they are a rarer chemical in the body, neurons will recycle the neurotransmitters through a process called re-uptake.

Remember: neurons are the nerve cells that create a giant communication network in our nervous system. There are two major types of neurons, motor neurons and sensory neurons, that allow us to (you guessed it) move around and feel things.

But how do these neurons talk to each other? That’s where the neurotransmitters come in. They are contained in a part of the neuron called the axon terminal button until they are sent to another neuron. Neurons never touch each other, so to get to that other neuron, the neurotransmitter has to cross a small gap called the synapse. The neurotransmitter then crosses over to the neighboring neuron and signals it to activate with an electrical impulse.

When a neuron is not “firing,” it is at its resting potential. When a neuron is signaled by a neurotransmitter to “fire,” leading to an action potential. This means that a neuron sends information down the axon of the neuron – the part that looks like a tail – away from the cell body. An action potential is sometimes referred to as an impulse.

Another important part of the neuron to remember when you’re thinking about neurotransmitters is the myelin sheath. The myelin sheath is a layer of fatty cells – also called glial cells – that surround the axon fibers of the neuron. The myelin sheath is important because it acts as a conductor and insulator, which makes the electrical impulse triggered by the neurotransmitters travel faster down the neurons.

In terms of neurotransmitters, the most important part of the neuron is the synapse. The synapse, or synaptic gap, is where the end of one neuron meets the beginning of another neuron. At the synaptic terminal, vesicles containing neurotransmitters connect to the synaptic membrane, releasing the neurotransmitters into the synaptic cleft. Then, the neurotransmitter binds to receptors on the postsynaptic side of the synapse – the dendrites of the next neuron. That receptive neuron then becomes more or less likely to fire an action potential, depending on the excitatory or inhibitory function of the neurotransmitter.

So that’s how the neurons use neurotransmitters to send messages to the brain. So far, researchers have identified about 15 to 20 neurotransmitters. In general, neurotransmitters can be divided into two types: excitatory and inhibitory. These categories are based on how a neurotransmitter behaves at the synapse – what it signals the next neuron to do. Excitatory neurotransmitters send signals that stimulate the brain. Inhibitory neurotransmitters send signals to calm the brain down and create balance. If they become overactive, excitatory neurotransmitters can easily overshadow the inhibitory neurotransmitters and reduce their effect.

Important Neurotransmitters to Know for the AP® Psych Exam

Agonists and Antagonists

Neurotransmitters don’t always act on their own. Drugs can affect the degree of a neurotransmitter’s impact. This effect on the neurotransmitter occurs at the synapse.

If a drug increases the effect of a neurotransmitter, it is called an agonist. So if an agonist acts on an excitatory neurotransmitter, the excitatory effect will increase. Here are some examples of common agonists:

• Caffeine: agonist for ACH.
• Selective Serotonin Reuptake Inhibitors (SSRIs): agonists for serotonin. SSRIs increase the amount of serotonin available to the brain, and are commonly prescribed for depression.
• Adderall, methamphetamine, cocaine, and speed: agonists of norepinephrine. When these drugs increase the excitatory effects of norepinephrine, they create feelings of euphoria and extreme alertness.
• Benzodiazepines and alcohol: agonists of GABA.
• Opiates (morphine, oxycodone, heroin, etc.): agonists of endorphins.

If a drug decreases the effect of a neurotransmitter, it is called an antagonist. So if an antagonist acts on an excitatory neurotransmitter, the excitatory effect will decrease. Here are some examples of common antagonists:

• LSD: antagonist for serotonin.
• PCP: antagonist of glutamate. PCP causes a dissociative state that inhibits memory and learning.
• Some drugs that are dopamine antagonists are used to treat psychosis, schizophrenia, and bipolar disorder.

Be careful: agonists and antagonists do not change the type of change a neurotransmitter causes. An antagonist will not change an excitatory neurotransmitter into an inhibitory one; it will just lower the degree of the excitatory response.

Reuptake Mechanisms

Sometimes, there are extra neurotransmitters left in the synapse. To avoid wasting these precious chemicals, the axon terminal will suck up the excess neurotransmitters to be recycled.

Some drugs are re-uptake inhibitors. These drugs do exactly what their name suggests – they prevent the axon terminals from engaging in the re-uptake of neurotransmitters. Cocaine, for instance, is a re-uptake inhibitor for dopamine. Its stimulating effects are caused by extra dopamine leftover in the synaptic gap.

What You Need to Know for the AP® Psychology Exam

Biological bases of behavior, including the function and types of neurotransmitters, make up about 8-10% of the total exam. According to the College Board’s AP® Psych course description, AP® Psych students should be able to talk about not only the different types of neurotransmitters, but also about the effects of drugs on their effects. This includes agonists, antagonists, and re-uptake mechanisms.

Neurotransmitters can also come into play on the AP® Psychology exam in discussions about sensation and perception, memory and learning, motivation and emotion, and abnormal behavior. Because of the wide variety of ways to think about neurotransmitters, it is important to understand both their functions and the problems associated with their surplus or deficit.

The College Board does not release multiple-choice questions from past AP® Psych exams. However, consider the following sample multiple-choice question from the AP® Psych course description:

Treating a patient for Parkinson’s disease includes administering a chemical that will lead to increases in the patient’s

(a) monoamine oxidase inhibitors (MAOIs)

(b) acetylcholine

(c) norepinephrine

(d) dopamine

(e) serotonin

The correct answer choice is D, dopamine. If you have studied our neurotransmitter chart, then you know that insufficient dopamine production is associated with Parkinson’s disease. However, your knowledge of other neurotransmitters, and the effect of drugs on their messages, can also help you narrow down possible answers in this kind of multiple-choice question.

Answer choice B is incorrect. Deficits of ACH are associated with Alzheimer’s disease, not Parkinson’s – dopamine is not associated with memory.Answer choices C and E, norepinephrine and serotonin, are both associated with mood disorders.

Now that you know norepinephrine and serotonin are not the correct answers, you also know answer choice A cannot be correct. Monoamine oxidase inhibitors, or MAOIs, are antidepressants that function by increasing the amounts of serotonin and norepinephrine, as well as blocking MAO, which breaks down many neurotransmitters.

Your knowledge of neurotransmitters may also be important on the Free-Response Section of the AP® Psych exam. Neurotransmitters are most likely to appear in a discussion of abnormal behavior, psychological disorders, and their treatment.

For instance, here is a past AP® Psych FRQ that asked students to discuss neurotransmitters:

Often misunderstood, schizophrenia is a psychological disorder affecting one percent of the population. In addition to treating the disorder, psychologists work to identify its nature and origins.

• Identify two characteristic symptoms used to diagnose schizophrenia.
• Discuss a research finding that supports a genetic basis for schizophrenia.
• What is the dopamine hypothesis regarding the origins of schizophrenia?
• Describe how medications used to treat schizophrenia affect the actions of neurotransmitters at the synapses.
• Identify a risk inherent in using medications in the treatment of schizophrenia.
• People sometimes confuse schizophrenia with dissociative identity disorder (DID). Identify two key characteristics that differentiate DID from schizophrenia.

You will need to know about more than just neurotransmitters to completely answer all parts of the prompt, but in this crash course review we will focus on the importance of neurotransmitters in understanding and treating schizophrenia.

The third point of this prompt asks you to explain the dopamine hypothesis. The dopamine hypothesis is that schizophrenia is caused by an over activity or excess of dopamine. A more specific way to answer this question is to explain that drugs that block dopamine decrease symptoms, and drugs that increase dopamine increase symptoms.

To answer the next point of the FRQ, you must explain that schizophrenia medications work by reducing dopamine activity. You can say this in any of the following ways: the medications lower levels of dopamine, prevent the release of dopamine, block dopamine receptors, or are dopamine antagonists. Just choose the explanation that makes the most sense to you. Remember to be clear and specific, and answer the question asked of you.

In other types of FRQs, you could be asked to connect the function of a specific neurotransmitter to its physical location. Here is another example FRQ:

For each of the following pairs of terms, explain how the placement or location of the first influences the process indicated by the second.

• Rods, peripheral vision
• A list of unrelated words, word recall
• Serotonin, reduction of depression
• Retinal disparity, depth perception
• Motor cortex, body movement
• Presence of others, performance
• Proximity, perception

Notice how the prompt asks you to explain how the placement of serotonin, not just its function, impacts the reduction of depression. It isn’t enough to say that serotonin is in the body. To answer this part of the prompt completely, you must indicate that increased amounts of serotonin in the brain are linked to reduced depression. You could also indicate that serotonin is located in the nervous system, neurons, synapses, receptors, or other neuron-related locations.

Phew – now you’ve made it through our crash course review of neurotransmitters. It’s a lot of information to take in, but we’ve given you all the tools you need to build a knowledge of neurotransmitters and apply your skills to multiple-choice questions and FRQs on the AP® Psychology exam.

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