Whatis Biopsychology? The OriginsofBiopsychology

Nature and Nurture Gar

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TheOriginsofBiopsychology • 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.

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TheOriginsofBiopsychology

• 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 MIND

BRAIN/ BODY

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MIND &

BRAIN/ BODY

 

   

   

   

TheOriginsofBiopsychology

• 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 1879.

Figure1.3:Descartes(1596-1650)

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Sources: (a) National Library of Medicine, (b) Corbis.

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TheOriginsofBiopsychology

• 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. G

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TheOriginsofBiopsychologyFigure 1.5: Paul Broca (1825-1880)

• Localization • Phineas Gage

• Broca and speech

• Phrenology • Gall’s extreme theory of localization

• http://phrenology.org

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SOURCES: Broca: Getty Images; Phrenology: Bettmann/Corbis

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TheOriginsofBiopsychologyFigure 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

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TheOriginsofBiopsychology

• 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. G

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Nature and Nurture

• Nature versusnurture 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.

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Nature and Nurture

• Genes • Fundamental unit of inheritance

• One direct function is to direct the building of proteins • Foundon Chromosomes

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Nature and Nurture Figure 1.8: A Set of Human Chromosomes

• Chromosomes • Body cells: 23 pairs of 2 (46 total) • Sex cells: 23 individual chromosomes. #23 of a sperm cell may be an X or a Y. #23 of an ovum will be an X. When combined, an XX pair will yield a female, and XY pair a male zygote

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SOURCE: US National Library of Medicine

     

  

   

Nature and Nurture

• Zygote is a fertilized egg. • 23 chromosomes from the male parent’ssperm. • 23 chromosomes from the female parent’sovum.

• Embryo • First 8 weeks of life

• Fetus • From 8 weeks to birth

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Nature and Nurture Figure 1.9: A Strand of DNA

• Deoxyribonucleicacid (DNA) • Double stranded chain

• Contains directions for making proteins

• Bases (A, T, G, C) are the genetic “alphabet”

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Nature and Nuture Application:AComputerMadeofDNA

GeorgeChurchhasalsousedDNAasa storagemediumfortext,graphicsand materialsfromhismostrecentbook.

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Nature and Nurture

• Different versions of a gene are called alleles • Alleles determine a characteristic (blood type) ordisease (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

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Nature and Nurture Figure 1.10: Blood types in the Offspring of Two Sets of Parents with Type ABlood

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Unrelated humans differ from one another (genetically) by only ½ of 1%. Monozygotic (identical) twins share 100% of their DNA. 16

   

 

  

   

 

Nature and Nurture

• 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

• Skincolor • Psychological disorders

• Genes do not provide a script for behavior, they control the production of proteins.

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Nature and Nurture Figure 1.11: Human Junk DNA Turns on Genes in a Mouse Embryo’s Paw

• Human Genome Project (1999-2003 and beyond) • Identify the genome, or all the geneson ourchromosomes

• What has the map revealed? • 97% of DNA is non-protein-encoding

• Role in gene expression

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• Humans share 98+% of our genes with chimps,butwevary dramatically in expression

SOURCE: Prabhakar, S., et al. 2008. Human-Specific Gain of Function in a Developmental Enhancer. Science, 321, 1348.

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Nature and Nurture Figure 1.12: Charles Darwin (1809-1882)

• 60-70 trillion possiblegenetic combinationsfrom two parents

• Sexual reproductionincreases variability ofoffspring, an essentialcomponent of Darwin’s Principle of Natural Selection. • Individuals whose genesprovide them with agreater ability to adapt aremore likely to survive, andpass on these beneficialgenes to more offspring.

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SOURCE: Courtesy of Library of Congress.

 

     

Nature and Nurture 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 concordancerate for twins

• Identical twins share 100% of their genes and DNA. • Fraternal twins share 50% of their genes & 99.5% DNA.

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SOURCE: Plomin, R., Owen, M.J., & McGuffin, P. 1994. The Genetic Basis of Complex Human Behavior. Science, 264, 1734.

     

 

 

Nature and Nurture

• 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. G

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