• Choose a category
• All
• Classic-Fiction

• Percentile score—the percentage of scores at or below a particular score.

• Correlation coefficient (r)—a statistical measure of the degree of relatedness or association between two sets of data that ranges from −1 to +1.

• Inferential statistics—statistics that are used to interpret data and draw conclusions.

• Statistical significance (p)—the condition that exists when the probability that the observed findings are due to chance is less than 1 in 20 (p < .05) according to some psychologists, or less than 1 in 100 (p < .01) according to those with more stringent standards.

• Ethical guidelines—suggested rules for acting responsibly and morally when conducting research or in clinical practice.

CHAPTER 7

Biological Bases of Behavior

IN THIS CHAPTER

Summary: As you read this page, lots of things are going through your mind. Your mind is what your brain does, according to many psychologists. The relationships of behavior, the mind, and the nervous system, especially the brain, have become increasingly clear as improvements in technology have enabled scientists to make better observations. In all areas of anatomy and physiology, structure is related to function. Specialized structures throughout your body enable regulatory function at all levels of organization from your neurotransmitter molecules to your nervous and endocrine systems.

Neuropsychologists explore the relationships between brain/nervous systems and behavior. Neuropsychologists are also called biological psychologists or biopsychologists, behavioral geneticists, physiological psychologists, and behavioral neuroscientists.

This chapter focuses on what we know about our nervous system and all of its parts at different levels of organization, and the tools that have enabled us to learn about them.

Key Ideas

Techniques to learn about structure and function

Nervous system organization

Brain structure and function

Neuron structure and functions

Endocrine system structure and function

Evolution and behavior

Genetics and behavior

Techniques to Learn About Structure and Function

As technology has improved, scientists have used a wide range of techniques to learn about brain and neural function. Over 150 years ago, studying patients with brain damage linked loss of structure with loss of function. Phineas Gage was the level-headed, calm foreman of a railroad crew (1848) until an explosion hurled an iron rod through his head. After the injury severed the connections between his limbic system and frontal cortex, Gage became hostile, impulsive, and unable to control his emotions or his obscene language. Observed at autopsy, his loss of tissue (where the limbic system is connected to the frontal lobes) revealed the relationship between frontal lobes and control of emotional behavior. In another case, Paul Broca (1861) performed an autopsy on the brain of a patient, nicknamed Tan, who had lost the capacity to speak although his mouth and vocal cords weren’t damaged and he could still understand language. Tan’s brain showed deterioration of part of the frontal lobe of the left cerebral hemisphere, as did the brains of several similar cases. This connected destruction of the part of the left frontal lobe known as Broca’s area to loss of the ability to speak, known as expressive aphasia. Carl Wernicke similarly found another brain area involved in understanding language in the left temporal lobe. Destruction of Wernicke’s area results in loss of the ability to comprehend written and spoken language, known as receptive aphasia.

“Structure is always related to function in living things.”

—Adrianne, AP teacher

Gunshot wounds, tumors, strokes, and other diseases that destroy brain tissue enabled further mapping of the brain. Because the study of the brain through injury was a slow process, quicker methods were pursued. Lesions, precise destruction of brain tissue, enabled more systematic study of the loss of function resulting from surgical removal (also called ablation), cutting of neural connections, or destruction by chemical applications.