Dopamine and serotonin are neurotransmitters--chemicals secreted by nerve cells that influence the activity of other nerve cells. They receive much attention from researchers, the press and the public for their particular activities and effects in the brain and body, which influence mental, emotional and physical health when they are not in balance.
Locations of Production and Receptors in the Brain
Serotonin production in the brain is localized in the raphe nucleus of the reticular formation, a diffuse aggregation of neurons in the brain stem that is responsible for conscious awareness and screening out of extraneous stimuli, and managing the sleep/wake cycle. Pathways for serotonin are present throughout the brain stem, cortex--the higher-level control centers and spinal cord, according to the website Brain Explorer.
Dopamine production is localized higher up in the brain, in an area known as the basal ganglia, which communicates with the cortex to control movement and learning. Receptor neurons for dopamine are widely distributed throughout the brain.
Pathways of Distribution in the Brain
Pathways for serotonin are present throughout the brain stem--where life support functions are located; cortex--the higher-level control centers; and spinal cord. The greatest concentrations of serotonin in the brain are found in the pineal gland, where it is converted to the hormone melatonin.
Receptor neurons for dopamine are widely distributed throughout the brain in three systems: the nigrostriatal--between the substantia nigra and the corpus striatum in the cerebral lobe; the mesocorticolimbic--connecting the midbrain to the limbic system--where arousal and emotions are generated; and the tuberohypophyseal--connecting the hypothalamus--which controls body temperature and appetite--to the pituitary gland, according to Brain Explorer.
Actions
Dopamine is involved in movement and also in motivational and pleasure seeking behaviors. Dopamine also modulates the transfer of information within the brain for tasks associated with memory, attention and problem-solving.
Serotonin plays a role in physical, emotional and psychological conditions such as depression, migraine headaches, bipolar disorder, anxiety and appetite. Serotonin acts a bit differently on each individual, making it a challenge to ascertain its precise effect on mood, says the International Society for Complexity, Information and Design.
Symptoms of Excess
Too much dopamine leads to uncontrollable movements such as tremors, twitches and repetitive tapping or jerking movements. The heart muscle responds to excess dopamine by increasing pulse rate and blood pressure from increased strength of contractions. This overworks the heart and leads to potential complications.
Excess serotonin leads to what is known as serotonin syndrome and is characterized by shivering, diarrhea, muscular rigidity, fever and seizures. This is a fatal condition in its extreme form, but symptoms usually subside within one day when the cause, usually a serotonin-increasing medication, is discontinued, according to the Mayo Clinic.
Symptoms of Deficiency
Fatigue, lack of motivation and depression are the behavioral hallmarks of low dopamine. Difficulty initiating and controlling the trajectory or precision of movement are the muscular manifestations.
Serotonin deficiency symptoms include anxiety, depression--with accompanying feelings of unworthiness and difficulty concentrating, fatigue, and sleep and appetite disorders. Premenstrual syndrome and bulimia can also occur in conjunction with low serotonin, according to the website Smart Publications.
