prevent their reuptake.

K E Y T A K E A W A Y S

•The central nervous system (CNS) is the collection of neurons that make up the brain and the spinal cord.

•The peripheral nervous system (PNS) is the collection of neurons that link the CNS to our skin, muscles, and glands.

•Neurons are specialized cells, found in the nervous system, which transmit information. Neurons contain a dendrite, a soma, and an axon.

•Some axons are covered with a fatty substance known as the myelin sheath, which surrounds the axon, acting as an insulator and allowing faster transmission of the electrical signal

•The dendrite is a treelike extension that receives information from other neurons and transmits electrical stimulation to the soma.

•The axon is an elongated fiber that transfers information from the soma to the terminal buttons.

•Neurotransmitters relay information chemically from the terminal buttons and across the synapses to the receiving dendrites using a type of lock and key system.

•The many different neurotransmitters work together to influence cognition, memory, and behavior.

•Agonists are drugs that mimic the actions of neurotransmitters, whereas antagonists are drugs that block the action of

neurotransmitters.

E X E R C I S E S A N D C R I T I C A L T H I N K I N G

1.Draw a picture of a neuron and label its main parts.

2.Imagine an action that you engage in every day and explain how neurons and neurotransmitters might work together to help you engage in that action.

3.2 Our Brains Control Our Thoughts, Feelings, and Behavior

L E A R N I N G O B J E C T I V E S

1.Describe the structures and function of the “old brain” and its influence on behavior.

2.Explain the structure of the cerebral cortex (its hemispheres and lobes) and the function of each area of the cortex.

3.Define the concepts of brain plasticity, neurogenesis, and brain lateralization.

If you were someone who understood brain anatomy and were to look at the brain of an animal that you had never seen before, you would nevertheless be able to deduce the likely capacities of the animal. This is because the brains of all animals are very similar in overall form. In each animal the brain is layered, and the basic structures of the brain are similar (see Figure 3.6 "The Major Structures in the Human Brain"). The innermost structures of the brain—the parts nearest the spinal cord—are the oldest part of the brain, and these areas carry out the same the functions they did for our distant ancestors. The “old brain” regulates basic survival functions, such as breathing, moving, resting, and feeding, and creates our experiences of emotion. Mammals, including humans, have developed further brain layers that provide more advanced functions— for instance, better memory, more sophisticated social interactions, and the ability to experience emotions. Humans have a very large and highly developed outer layer known as the cerebral cortex (see Figure 3.7 "Cerebral Cortex"), which makes us particularly adept at these processes.

Figure 3.6 The Major Structures in the Human Brain

The major brain parts are colored and labeled.

Source: Adapted from Camazine, S. (n.d.). Images of the brain. Medical, science, and nature things: Photography and digital imagery by Scott Camazine. Retrieved from http://www.scottcamazine.com/photos/brain/pages/09MRIBrain_jpg.htm.

Figure 3.7 Cerebral Cortex

Humans have a very large and highly developed outer brain layer known as the cerebral cortex. The cortex provides humans with excellent memory, outstanding cognitive skills, and the ability to experience complex emotions.