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Chapter 1 The Major Issues. Biological Psychology. The study of the physical roots of behavior. Emphasizes: Physiology Evolution (genetics) Development Brain functioning. Brain functioning on a microscopic level: neurons and glia, the cells of the brain.
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Biological Psychology • The study of the physical roots of behavior. • Emphasizes: • Physiology • Evolution (genetics) • Development • Brain functioning
Brain functioning on a microscopic level: neurons and glia, the cells of the brain
Biological explanations of behavior fall into four categories: • Physiological- emphasis on brain and other vital organs. • Ontogenetic- describes the development of a structure or behavior. • Evolutionary- focuses upon the genetic history of a behavior. • Functional- describes why a structure or behavior evolved as it did.
The Mind-Brain Relationship • Biological explanations of behavior bring into focus the relationship between the mind and the brain, also known as the “mind-body” or “mind-brain problem”. • The “mind-brain problem” has a variety of explanations.
Dualism isthe belief that there are different kinds of substances and the mind and the body are separate entities. • Defended by French philosopher Rene Descartes. • Most common belief among nonscientists. • Rejected by most neuroscientists.
The Mind-Brain Relationship • Monism is the belief that the universe is only comprised of one type of substance. • Forms of monism include: • Materialism- everything that exists is physical by nature. • Mentalism- only the mind truly exists. • Identity position- mental processes are the same as brain processes but simply described in different ways.
The Genetics of Behavior • Both genes and environment interact to shape human behavior. • How much of a role does genetics play in shaping human behavior? • Examples: psychological disorders, weight gain, personality, sexual orientation, sexual identity?
“Bringing Up Monkey” Link to Video
The mechanism used to pass the message of inheritance from one generation to the next. A trait that depends largely on hereditary influences is said to have high heritability. Heredity
Researchers study monozygotic (identical) and dizygotic (fraternal) twins to infer how much of a genetic component exists for a particular behavior. Researchers also study adopted children and their resemblance to their biological parents to infer the influence of heredity. Research: Twins and Adopted Children
Genetic tendencies that guide behavior will result in a change in the environment that magnifies the original tendency. Multiplier effect
Traits with a strong hereditary influence can be modified by environmental intervention. PKU (phenylkentonuria): a genetic inability to metabolize phenylalanine that results in brain damage—unless phenylalanine is removed from the diet
Chromosomes contain genetic information 46 chromosomes in every cell Exception: Sex cells (eggs and sperm) have 23 Sexual reproduction involves making 23 new chromosome pairs Genetics of Human Life
The 23rd chromosome pair (sex chromosomes) determines sex of child During reproduction: Females contribute an X chromosome. Males contribute either an X or a Y chromosome that determines the sex of the child. If X, female If Y, male
Basic units of heredity that maintain their structural identity from one generation to another Inheritance through genes was demonstrated by 19th century monk Gregor Mendel Strands of genes form chromosomes Genes
A double-stranded chemical that contains genetic information Genes/chromosomes are composed of DNA Deoxyribonucleic Acid (DNA)
One strand of DNA serves as a model for the synthesis of ribonucleic acid (RNA). Fig. 1-7, p. 12
Ribonucleic acid (RNA) • A single strand chemical that can serve as a template/model for the synthesis of proteins. • Proteins determine the development of the body by: • forming part of the structure of the body. • serving as enzymes that serve as biological catalysts and regulate chemical reactions in the body.
Homozygous for a gene: identical pair of genes on the two chromosomes Heterozygous for a gene: unmatched pair of genes on the two chromosomes A dominant gene shows a strong effect in either the homozygous or heterozygous condition. A recessive gene shows its effect only in the homozygous condition. Pea plant flowers (parents are heterozygous for color): Genes come in pairs
Dominant traits: Recessive traits: Genes can be dominant or recessive
Example: The ability to taste PTC (phenylthio-carbamide), a bitter organic compound, is dominant Fig. 1-8, p. 13
Types of genes include: • Autosomal genes - all genes except for sex- linked genes. • Sex-linked genes -genes located on the sex chromosomes.
Y chromosome: genes for 27 proteins X chromosome: genes for approximately 1500 proteins Thus, sex-linked genes usually refer to X-linked genes. (Example: Red-green color deficiency) Sex-limited genes are genes that are present in both sexes but mainly have an effect on one sex (Chest hair, breast size, etc.) Human Sex-linked genes
Recombination refers to a new combination of genes in the off-spring that yield characteristics not found in either parent. Mutation refers to a change in a single gene that is rare, random and often independent of the needs of the organism. Genetic Variation
Evolution of Behavior • Evolution refers to a change in the frequency of various genes in a population over generations • Evolution attempts to answer two questions: • How did some species evolve? • How do species evolve?
Evolutionary psychology focuses on functional explanations of how behaviors evolved. • Assumes that behaviors characteristic of a species have arisen through natural selection and provide a survival advantage. • Examples: differences in peripheral/color vision, sleep mechanisms in the brain, eating habits, temperature regulation.
Organisms with desired traits are chosen to be parents of the next generation Used by breeders Sometimes used by human parents Artificial Selection
The Use of Animals in Research • Important source of information • Highly controversial topic • Amount of stress and/or pain that is caused to the animal varies • Colleges and research institutions in the US are required to have an Institutional Animal Care and Use Committee (IACUC). • Oversees and determines acceptable procedures.
Reasons for studying animals include: • The underlying mechanisms of behavior are similar across species and often easier to study in nonhuman species. • We are interested in animals for their own sake. • What we learn about animals sheds light on human evolution. • Some experiments cannot use humans because of legal or ethical reasons.
Opposition to animal research varies: “Minimalists” favor firm regulation on research and place consideration upon the type of animal used and the amount of stress induced. “Abolitionists” maintain that all animals have the same rights as humans and any use of animals is unethical. The Use of Animals in Research