Neuronal communication involves the use of different neurotransmitters at synapses. The variety of these neurotransmitters can influence behavior.
Neuronal communication is an electrochemical event. The dendrites contain receptors for neurotransmitters released by nearby neurons. If the signals received from other neurons are sufficiently strong, an action potential will travel down the length of the axon to the terminal buttons, resulting in the release of neurotransmitters into the synapse.There are several different types of neurotransmitters released by different neurons, and we can speak in broad terms about the kinds of functions associated with various neurotransmitters. Much of what psychologists know about the functions of neurotransmitters comes from research on the effects of drugs in psychological disorders. Psychologists who take a biological perspective and focus on the physiological causes of behavior assert that psychological disorders like depression and schizophrenia are associated with imbalances in one or more neurotransmitter systems. In this perspective, psychotropic medications can help improve the symptoms associated with these disorders. Psychotropic medications are drugs that treat psychiatric symptoms by restoring neurotransmitter balance.
Psychoactive drugs can act as agonists or antagonists for a given neurotransmitter system. Agonists are chemicals that mimic a neurotransmitter at the receptor site and, thus, strengthen its effects. An antagonist, on the other hand, blocks or impedes the regular activity of a neurotransmitter at the receptor. Agonist and antagonist drugs are prescribed to correct the specific neurotransmitter imbalances underlying a person’s condition. For example, Parkinson’s disease, a progressive nervous system disorder, is associated with low levels of dopamine. Therefore dopamine agonists, which mimic the effects of dopamine by binding to dopamine receptors, are one treatment strategy.Specific symptoms of schizophrenia are associated with overactive dopamine neurotransmission. The antipsychotics used to treat these symptoms are antagonists for dopamine—they block dopamine’s effects by binding its receptors without activating them. Thus, they prevent dopamine released by one neuron from signaling information to adjacent neurons.
Key Points
• Neuronal communication is an electrochemical event.
• There are several different types of neurotransmitters released by different neurons, and we can speak in broad terms about the kinds of functions associated with various neurotransmitters
• Psychoactive drugs can act as agonists or antagonists for a given neurotransmitter system. Agonists are chemicals that mimic a neurotransmitter at the receptor site and, thus, strengthen its effects. An antagonist, on the other hand, blocks or impedes the regular activity of a neurotransmitter at the receptor.
• In contrast to agonists and antagonists, which both operate by binding to receptor sites, reuptake inhibitors prevent available neurotransmitters from being transported back to the neuron. This leaves more neurotransmitters in the synapse for a longer time, increasing its effects.
Key Terms
neurotransmitters: a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure
biological perspective: a way of looking at psychological issues by studying the physical basis for animal and human behavior
psychotropic medication: any drug that affects behavior, mood, thoughts, or perception
agonist: chemicals that mimic a neurotransmitter at the receptor site and strengthen its effects
antagonist: blocks or impedes the normal activity of a neurotransmitter at the receptor
dendrite: branched projections of a neuron that conduct the impulses received from other neural cells to the cell body
neurons: a basic working unit of the brain
action potential: the electrical message sent down a neuron