PY253, Week 1 Notes Cont.
PY253, Week 1 Notes Cont. PY253
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This 70 page Class Notes was uploaded by Sarah Atkinson on Thursday January 21, 2016. The Class Notes belongs to PY253 at University of Alabama at Birmingham taught by Dr. Trost in Winter 2016. Since its upload, it has received 54 views. For similar materials see Brain Mind and Behavior in Psychlogy at University of Alabama at Birmingham.
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Date Created: 01/21/16
Biopsychology Basics PY 253-2C: Brain, Mind and Behavior Zina Trost, PhD Today’s Class 1) The Dichotomies: Physiological vs. Psychological….. Nature vs. Nurture? 2) Understand how Evolution is involved in Behavior 2) Basics of Genetics 3) Provide an example of genetics in action Today’s Class (1) THE DICHOTOMIES DICHOTOMIES: What are they? Dichotomy = When something is divided into two separate parts Like: Physiology or Psychology? Like: Nature or Nurture? We like to think this way. Why? DICHOTOMY 1: Physiological vs. Psychological? th Step 1: 17 Century Europe: Science vs. Church Step 2: Enter Renee Descartes CARTESIAN DUALISM • SCIENCE: Physical world • CHURCH: Spiritual world: human mind, soul, self, sprit …Mind controls human behavior …and also, you can do autopsies now! Step 3: People buy into it • CARTESIAN DUALISM = human activity that is independent of the brain DICHOTOMY 2: Is it Inherited or Learned? AKA: Nature vs. Nurture GENETICS vs. EXPERIENCE? Tell me you have never thought this way. DICHOTOMIES: SO MANY PROBLEMS DICHOTOMY 1: Physiological vs. Psychological? PHYSIOLOGICAL vs. PSYCHOLOGICAL AKA: BRAIN vs. MIND QUESTION: Can a brain really do this? Argument 1: Brain injury Psychological changes Argument 2: “Mind” in non-human species Argument 1: Brain injury Psychological changes BRAIN DAMAGE CHANGES PSYCHOLOGICAL FUNCTIONING AND PERSONALITY EXAMPLE: ASOMATOGNOSIA Aghh! Whereis my leg? And what is that attached to me? Argument 2: “Mind” in non-human species CHIMPS ARE SELF-AWARE (REALLY) Less complex brains, but pretty complex Behavior! DICHOTOMY 2: NATURE vs NURTURE DICHOTOMY 2: NA TURE vs NURTURE Is this better? “Howmuch of it is genetic and how much of it is the result of experience?” No…. WHY NOT: STILL NOT ANINTERACTION Current thought: How Biopsychologists think: Natureand nurture interact in many ways to make youunique. Behavior is best viewed as the product of: • genetic potential interacting with… • past experience and … • current situational factors Today’s Class (2) EVOLUTION EVOLUTION First, the basics Mr . Darwin On the Origin of Species (1859) • Postulated that species evolved as adaptation to their environment • Was the first to collect really good evidence (give me a minute) • Was first to suggest a mechanism (psst: natural selection”) The most influential theory. Darwin’s Evidence 1) Fossil records. 2) Structural similarities. Darwin’s Evidence 3) Selective Breeding 4) Modern Studies: Rapid evolution in progress! Darwin’s Big Idea Natural Selection: The mechanism of evolution! • First: Members of each species VARY a great deal • Second: Some characteristics are associated with better FITNESS FITNESS = HIGH RATES OF SURVIVAL AND REPRODUCTION • These characteristics are most likely to be passed on • “Survival of the fittest” • Leads to better adaptation to environment Lots of things evolve over time Not just structure: Also behavior! Think about it: Behavior is also important to fitness OBVIOUS Behaviors that contribute to fitness: • Eating, not getting eaten NOT SO OBVIOUS: • Social Aggression • Courtship Hierarchies Socially Dominant Males and Females Example: So: How is this related to evolution? Terms to Know: 1) Species: a group of reproductively isolated organisms that can produce fertile offspring (can exchange genes, interbreed) • Sometimes not so much 2) Conspecifics: members of the same species that are reproductively set apart for one reason or another… • Religious beliefs • Courtship behaviors • Geographical isolation EVOLUTION Course of Human Evolution 1. Evolution of Vertebrates 1) 600 million years ago: multiple celled organisms 2) 450 millions years ago: chordates (dorsal nerve cords) 3) 425 million years ago: chordates with backbones (vertebrates!) At that point: Just bony fishes :-/ 2. Evolution of Amphibians 410 million years ago: Bony fish go for a walk (venture onto land). Lucky because…. • More food sources • Fresher water Natural selection: • Fins Legs • Gills Lungs 3. Evolution of Reptiles 300 million years ago: Reptiles evolve from a branch of amphibians • Lizards, snakes, turtles • Eggs! • Why Eggs? Why Scales? • Less reliant on water. 4. Evolution of Mammals 180 million years ago… (there are dinosaurs) • Branch of reptiles • Mammary glands • Stopped laying eggs (instead: bodies) • Longer development – more complex Today: 20 different orders of mammals exist • The order we belong to are … primates! Let’s take a moment for Primates Primates • The order we belong to • Hard to categorize based on traits • Chimpanzees share about 99% of our DNA 75% of ourDNA?hares 5. Emergence of Humankind Humankind (Hominins) Evolutionary Stages: • 6 million years ago: Australopithecines (Around for about 5 million years) • 2 million years ago, Homo speciesevolved • Larger brain size than the previous guys • But not as large as humans today • 200,000 years ago, Homo sapiens show up in the fossil record • 50,000 years ago, modern humans migrate out of Africa EVOLUTION Some Thoughts and Some T erms 8 Useful Thoughts about Evolution 1. Not a straight line and not always better 2. Humans are very recent and not the “best” 3. Evolution can be slow or fast 4. Present species represent a fraction (1%) of the species that have evolved on earth. 8 Useful Thoughts about Evolution 5. Evolution is not a perfectionist 6. Evolution is not always adaptive 7. Sometimes structures or behaviors evolve in response to one type of evolutionary pressure, but later perform a different function 8. Similarities do not necessarily mean common ancestors 3 Useful Evolutionary Terms 1) Homologous: Similar structures due to common origin 3 Useful Evolutionary Terms 2. Analogous: Similar structures without a common origin 3 Useful Evolutionary T erms 3) Convergent Evolution: Similar evolution due to same environmental demands …. Structures are analogous Today’s Class (3) BASICS OF GENETICS Gregor Mendel Step 1: Remember the Cell? Chromosomes, Genes, and Alleles Chromosomes: Thread-like structures in the nucleus of each cell Chromosome are composed of strands of DNA Genes are short segments of your DNA that control a certain trait. Recipes for proteins. Chromosomes, Genes, and Alleles Human specieshas 23 pairs of chromosomes (46) One pair from each parent Chromosomes, Genes, and Alleles 2 Genes control a certain trait. Genes come in variations (2+). One variation = Allele Alleles are the two genes that control the same trait. • Gene for eyecolor has several allele types • Example: Brown eyes Chromosomes, Genes, and Alleles One allele from Dad, and the other from Mom WAIT : Genotype and Phenotype GENOTYPE • Your genetic make up; What alleles are present PHENOTYPE • Physical traits expressed as a result of what alleles are present • Blue eyes Types of Alleles: Homozygous and Heterozygous Homozygous • Two copies of the same allele for a given trait • Blue eyes (bb) Heterozygous • Two different alleles for a given trait • Brown eyes (Bb) Types of Alleles: Dominant and Recessive DOMINANT ALLELE • An allele that masks the expression of other alleles • Brown eyes (B) RECESSIVE ALLELE • An allele that is only expressed in the absence of another allele • Blue eyes (b) Same Trait Homozygous Heterozygous BB Bb The Punnett Square The Punnett Square • Used to predict genotype/phenotype • Only when you know the parental genotypes • Can also be used in reverse The Punnett Square B b B b The Punnett Square B b homozygous dominant B BB b The Punnett Square B b heterozygous B BB Bb b Bb The Punnett Square B b homozygous recessive B BB Bb b Bb bb Putting together Dominant/Recessive and Homozygous/Heterozygous bb BB Putting together Dominant/Recessive and Homozygous/ Heterozygous bb Bb BB Putting together Dominant/Recessive and Homozygous/ Heterozygous bb Bb BB Bb Putting together Dominant/Recessive and Homozygous/Heterozygous bb Bb BB bb Bb Because, remember? B b B BB Bb b Bb bb Ummmm…. bb Bb bb Good Genetic T erms to know Replication : The doubling of DNA for two identical replicas from one original • Allows cell to divide • 4 nucleotidebases: adenine, thymine, guanine, and cytosine • Duringreplication…. Mutation: Whenthings go wrong: An error in DNA replication HumanGenomeProject (1990) • Let’s sequence all human genes! • Approximately 20,000 genes in a human (vs. um, corn) • Surprise! Genes are only 1% of human DNA…”JUNK DNA”… or is it? • Originally medical hopes, but… EPIGENETICS Epigenetics • The study of changes in an organism that is due to expression of genes, not changes in genes themselves. • So: small number of genes • Example: “Junk DNA”? • Experience can alter gene expression • ….and be passed on! Today’s Class (4) GENETICS IN ACTION ! Genetics in Action: Rats in Mazes SelectiveBreeding • “Maze-bright” and “Maze-dull” rats… for 21 generations of rats Genetics in Action: Rats in Mazes So, what does this demonstrate? Also… other features are selected And: Gene- environment (experience) interaction! Genetics in Action: Doggies Mutation in action: A one gene problem Phenylketonuria (PKU) • Fölling diagnosed his kids • Caused by a single recessive gene mutation • Buildup of phenylalanine • Inability to convert phenylalanine to tyrosine • Leads to abnormal brain development • Can be preventedby diet • SO: Gene-environment interaction How to do genetics… Wrong Minnesota Twin Study • Monozygotic vs. Dizygotic twins raised together or raised by different families • Personality and Intelligence tests (many, many…) • In general… • Found that heritability estimates for IQ were .70. “70% of intelligence is genetic” What is a “Heritability Estimate” Heritability Estimate– proportion of the variability in a trait that can be accounted for by genetic differences BUT: In a particular study NOTHING to say about the contribution of genes or experience for a particular individual SO: What’s wrong with saying that 70% of intelligence is genetic? So…. Heritability Estimate • Must take genetic AND environmental factors into account • Not easy to generalize to other situations So when you hear: “Complex traits and behaviors have substantial heritability estimates… between 40% and 80%” … what should you think of? Future Studies: Twin studies of Epigenetic Effects • Epigenetic changes, triggered by environmental experience • Look at Monozygotic Twins’ DNA as they grow • Compare at different ages Big implication!!! Future Studies: Twin studies of Epigenetic Effects Disorders not shared by twins suggest epigenetic component Disease-discordant monozygotic twins • e.g., one has schizophrenia and the other does not. Effects of Experience Turkheimer et al. (2003) Heritability estimate of IQ in… …. High SES environment (.70) …. Low SES environment (.10)
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