What is Biopsychology?

Transcription

1 What is Biopsychology? The Origins of Biopsychology Nature and Nurture 1

2 The Origins of Biopsychology What is Neuroscience? The multidisciplinary study of the nervous system s role in behavior What is Biopsychology? Study of body / behavior relationships by psychologists. What are the annual costs of brain disorders and addictions? A trillion dollars!?! What kinds of questions do neuroscientists study? 1990 was the decade of the brain, but lots of elaborate and expensive studies are under way right now in Europe and the U.S. of A. Many of them are oriented toward building computer models. 2

3 The Origins of Biopsychology The mind-brain problem What is the mind, and what is its relationship to the brain? Monism Mind and body are single substance Mentalistic monism (all mind) Materialistic monism (all physical) Dualism Mind and brain are separate One can exist without the other BRAIN/ BODY MIND & BRAIN/ BODY MIND 3

4 The Origins of Biopsychology Model- proposed mechanism for how something works Descartes Hydraulic model: Animal spirits and the pineal gland, eventually rejected Empiricism Information through observation Wilhelm Wundt Founded the first psychology laboratory in Leipzig, Germany in Figure 1.3: Descartes ( ) 4 Sources: (a) National Library of Medicine, (b) Corbis.

5 The Origins of Biopsychology The Electrical Brain Galvani (late 1700s) Muscles respond to electricity Fritsch & Hitzig (1870) Movement results from electrical stimulation of the brain Helmholtz calculated the speed of nerve impulses (90 feet per second). Slow? Established that: Neural conduction is biological in nature. Neural functioning is open to scientific study. 5

6 The Origins of Biopsychology Figure 1.5: Paul Broca ( ) Localization Phineas Gage Broca and speech Phrenology Gall s extreme theory of localization 6 SOURCES: Broca: Getty Images; Phrenology: Bettmann/Corbis

7 The Origins of Biopsychology Figure 1.7: Some of the Brain s Functional Areas Equipotentiality (Lashley) Damage extent, not location, determines amount of function lost. Localization and Distribution of function 7

8 The Origins of Biopsychology The brain-mind problem is still being debated. Discovery Institute Promotes intelligent design, nonmaterial view. The institute funds non-material neuroscientists. Non-materialists: psychotherapy changes brain activity as evidence of mind changing the brain. The materialist neuroscientists response: This research can also be interpreted as the brain changing the brain. 8

9 Nature versus nurture question How important are environmental influences (nurture) in shaping behavior? Arguments are often based on emotion, not evidence. An increasing number of behaviors are turning out to have some degree of hereditary influence (nature). Necessary to understand what nature and heredity are. Let s start with the nature piece. 9

10 Genes Fundamental unit of inheritance One direct function is to direct the building of proteins Found on Chromosomes 10

11 Figure 1.8: A Set of Human Chromosomes Chromosomes Body cells: 23 pairs of 2 Sex cells: 22 pairs of 2, 1 pair sex chromosomes XX produces female, XY produces male 11 SOURCE: US National Library of Medicine

12 Zygote is a fertilized egg. 23 chromosomes from the male parent s sperm. 23 chromosomes from the female parent s ovum. Embryo First 8 weeks of life Fetus From 8 weeks to birth 12

13 Figure 1.9: A Strand of DNA Deoxyribonucleic acid (DNS) Double stranded chain Contains directions for making proteins Bases (A, T, G, C) are the genetic alphabet 13

14 Nature and Nuture Application: A Computer Made of DNA George Church has also used DNA as a storage medium for text, graphics and materials from his most recent book. Garrett: Brain & Behavior 4e * 14

15 Different versions of a gene are called alleles Alleles determine a characteristic (blood type) or disease (Huntington s disease), 1 on each chromosome Dominant alleles (R) Expressed regardless of the other allele (A, B blood alleles) Recessive alleles (r) Only expressed when by itself (O blood allele) Homozygous versus Heterozygous Genotype versus Phenotype X-linked traits Unpaired in men (XY)- affected or not Paired in women (XX)- normal, carrier, or affected 15

16 Figure 1.10: Blood types in the Offspring of Two Sets of Parents with Type A Blood Unrelated humans differ from one another (genetically) by only ½ of 1%. Monozygotic (identical) twins share 100% of their DNA. 16

17 Some traits are determined by a single pair of alleles. This is rare. Most characteristics are determined by several genes and hence are referred to as polygenic traits. Height Intelligence: The most investigated characteristic thus far Skin color Psychological disorders Genes do not provide a script for behavior, they control the production of proteins. 17

18 Figure 1.11: Human Junk DNA Turns on Genes in a Mouse Embryo s Paw Human Genome Project ( and beyond) Identify the genome, or all the genes on our chromosomes What has the map revealed? 97% of DNA is non-protein-encoding Role in gene expression Humans share 98+% of our genes with chimps, but we vary dramatically in expression 18 SOURCE: Prabhakar, S., et al Human-Specific Gain of Function in a Developmental Enhancer. Science, 321, 1348.

19 Figure 1.12: Charles Darwin ( ) trillion possible genetic combinations from two parents Sexual reproduction increases variability of offspring, an essential component of Darwin s Principle of Natural Selection. Individuals whose genes provide them with a greater ability to adapt are more likely to survive, and pass on these beneficial genes to more offspring. 19 SOURCE: Courtesy of Library of Congress.

20 Figure 1.13: Twin Studies of Behavioral and Medical Disorders Heritability: Percentage of variation in a characteristic that is attributed to genetics. Calculated by comparing concordance rate for twins Identical twins share 100% of their genes and DNA. Fraternal twins share 50% of their genes & 99.5% DNA. 20 SOURCE: Plomin, R., Owen, M.J., & McGuffin, P The Genetic Basis of Complex Human Behavior. Science, 264, 1734.

21 Variability in behavioral characteristics Interaction of genetic and environmental influences. Genes fluctuate their activity levels over time, as well as the timing for when they become active / inactive Vulnerability: More genes for a disorder reduces the threshold required to produce it. Most scientists reject the Nature versus Nurture concept, adopting a Nature AND Nurture approach. 21