Chapter 1

THE MAJOR ISSUES

I The Mind-Brain Relationship

Big Question: How does clump in brain cause consciousness?? Or, How does matter, physical world give rise to mental/ Psych experience?

Smaller/ Easier/ Specific Question: Which genes/ Biological factors cause scizophrenia, depression etc? Which brain area is involved in fear, learning…?

A Biological Psychology: The study of the physiological, evolutionary, and developmental mechanisms of behavior and experience. Much of biological psychology is devoted to studying how the brain functions.

B Biological explanations of behavior fall into four categories:

1. Physiological explanations: Relates behavior to the activity of the brain and other organs. Deals with the machinery of the body.

2. Ontogenetic explanations: Describes the development of a structure or a behavior. Looks at the influence of genes, nutrition, experience and the interaction among these influences on behavior.

3. Evolutionary explanations: Examines a structure or a behavior in terms of evolutionary history. Examines the continuity (unbroken course) of a behavior from past ancestors to the present.

4. Functional explanations: Describes why a structure or behavior evolved as it did.

Looks for the benefit or advantage for having certain behaviors.

Example: Goosebumps / rubbing skin when cold

C The Brain and Conscious Experience

1. The mind-body or mind-brain problem: What is the relationship between the mind and the brain?

2. Dualism: The belief that mind and body are different kinds of substances (thought substance and physical substance), that exist independently but somehow interact.

3. Monism: The belief that the universe consists of only one kind of existence. Monism comes in various forms which primarily fall in the following categories:

Materialism: The view that everything that exists is material or physical. Psychology can eventually be explained in physical terms.

Mentalism: The view that only the mind really exists. Physical is in our (or God’s) imagination

Identity position: The view that the mental processes are the same as certain kinds of brain processes, but described in different terms.

II. Nature and Nurture

A Genetics Of Behavior

1. Gregor Mendel (monk experimenting on peas, end 19^th century): inheritance occurs through genes (prior to that thought that: inheritance is like mixing paint!)

2. Genes: - units of heredity that maintain their identity from one generation to the next.

- aligned along chromosomes (strands of genes). Chromosomes come in pairs, except sex chromosomes which do not come in pairs

3. Chromosome: composed of a double-stranded chemical called DNA

4. A strand of DNA (deoxyribonucleic acid) serves as a template (model) for the synthesis of ribonucleic acid (RNA).

5. RNA is a single-stranded chemical: one type of RNA serves as a template for the synthesis of protein molecules. (FIG 1.6)

6. Proteins can be part of the structure of the body or serve as enzymes (biological catalysts that regulate chemical reactions in the body).

7. If individuals have an identical pair of genes on the two chromosomes, they are homozygous for that gene; if they instead have an unmatched pair of genes, they are heterozygous for that gene (e.g., a gene for black hair on one chromosome and a gene for brown hair on the other).

8. Certain genes can be identified as dominant or recessive.

Dominant genes show a strong effect in either homozygous or heterozygous conditions; recessive genes show their effects only in homozygous conditions (e.g., a carrier for both a black hair gene dominant and a brown hair gene (recessive) will have black hair).

9. In certain cases, the inheritance of one gene is linked to inheritance of another gene. This typically happens when two genes are on the same chromosome.

Crossing over is an exception to the linkage of inheritance of genes on the same chromosome where chromosome pairs will break apart and reconnect to each other during reproduction. Leads to greater genetic variety.

10. All mammalian chromosome pairs (with the exception of sex chromosomes) are referred to as autosomal chromosomes. Genes located on autosomal chromosomes are autosomal genes; genes located on sex chromosomes are sex-linked genes.

11. A female mammal has two X chromosomes; a male has one X and one Y (small!) chromosome.

12. The Y chromosome carries the gene which causes the person to develop as a male; the X chromosome carries many genes (these are usually referred to as sex-linked genes). Since they don’t have a counterpart on the Y chrom, recessive genes on X are expressed in males, but not often in females, since the other X might have the dominant gene that outweighs the recessive gene. Ex Color blindness, hemophilia

13. Sex-linked recessive genes have their effects only in the absence of the dominant gene.

14. Sex-limited genes: Have an effect in only one sex or at least a much stronger effect in one sex. Such genes need not be on sex chromosomes and both sexes will have these genes. The differential effect is because these genes must be activated by sex hormones.

15. Evolution is only possible when variation exists. Two common sources of variation are recombination and mutation.

Recombination: A new combination of genes that occurs during reproduction

Mutation: A random change in a single gene; most mutations produce recessive genes.

16. Heritability: An estimate of how much of the variance in some characteristic is due to heredity. Heritability ranges from 0 to 1. A heritability of 1 indicates that heredity is responsible for all observed differences; a heritability of 0 indicates heredity is responsible for none of the observed differences.

17. Heritability in humans is studied in two ways. First by comparing monozygotic (identical) twins and dizygotic (fraternal) twins. Second, by comparing adopted children and their biological parents.

18. Environmental influences may affect traits with high heritability (e.g., Phenylketonuria (PKU): A genetically caused form of mental retardation that can be avoided with a strict diet that prevents build up of phenylalanine).

19. Genes affect behavior through the proteins they produce and their influence on specific body systems.

1. Evolution: Change over generations in the frequencies of various genes in a population.

2. Offspring generally resemble their parents, but because of mutations and recombinations new inheritable variations in the gene pool can occur.

3. Artificial-selection: Breeding animals for desirable individual characteristics (this causes changes in various genetic frequencies in a population).

4. Misconceptions in evolution:

· Lamarckian evolution: Use or disuse of some structure or behavior causes an evolutionary increase or decrease in that feature.

· Humans are no longer evolving because of modem medicine and prosperity.

· Evolution necessarily improves the fitness (the number of copies of one' s genes that endure in later generations) of the population.

· Evolution acts to benefit the individual or the species.

5. Altruistic behavior: Behaviors that benefit others rather than the individual committing the behavior. This is in contrast to the belief that genes evolve for their own benefit.

If altruistic genes exist, they may spread through reciprocal altruism (the notion that animals help those that help themselves) or kin selection (selection in favor of a gene because it benefits the animal's relatives)