The brain consists of many subdivisions and parts. The outermost portion, which is the wrinkled, grayish portion of the brain most familiar to many individuals, is called the cerebral cortex. This part of the brain is subdivided further, with the portions on the sides of the brain, just above each ear, called the temporal lobes. These areas of the cortex engage in production of language and the sensation of hearing, among other functions. There are several major neurotransmitters, or chemicals, of the temporal lobes.
Noradrenaline
One of the major neurotransmitters of the temporal lobes of the brain is noradrenaline, also called norepinephrine. This compound is chemically similar to epinephrine, or adrenaline, which is a hormone made by a gland on top of the kidney, explains Dr. Lauralee Sherwood in her book, "Human Physiology." Unlike adrenaline, however, noradrenaline is made by--and sensed by--neurons in the brain. Its primary purpose is to help maintain arousal, meaning an individual's ability to stay aware of and pay attention to surroundings. It also plays a part in endogenous reward systems, meaning that it helps indicate to an individual that they've done something "good" that promotes life.
Serotonin
Another important temporal neurotransmitter is serotonin, one of the brain's "happy" neurotransmitters. Serotonin helps ensure that neurons of the brain get the message that a person feels comfortable, relaxed and secure. A lack of serotonin can lead to depression, anxiety and other psychiatric disorders. In their book "Biochemistry," Drs. Reginald Garrett and Charles Grisham explain that the brain makes serotonin from the amino acid tryptophan, which is a component of protein. While most individuals produce serotonin in appropriate quantities as needed, serotonin synthesis in the neurons tends to increase when blood levels of tryptophan are high, or after eating a high-carbohydrate meal.
Acetylcholine
Acetylcholine is another important temporal lobe neurotransmitter. It's intimately involved in learning and short-term memory, explains Dr. Neil Carlson in his book, "Foundations of Physiological Psychology." Acetylcholine doesn't only appear in the brain--in fact, it plays important roles in other portions of the nervous system as well. For instance, it's the neurotransmitter that motor neurons use to communicate with muscles, and in this context, it signals muscles to contract and produce movement. In neuron-to-neuron communication in the brain, however, acetylcholine plays a different role--it stimulates neural pathways in such a way that the pathways become "established," producing new memories or learned behaviors.
References
- "Human Physiology"; L. Sherwood, Ph.D.; 2004
- "Biochemistry"; R. Garrett, Ph.D. and C. Grisham, Ph.D.; 2007
- "Foundations of Physiological Psychology"; N. Carlson, Ph.D.; 2004
