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Unformatted text preview: 1 Behavioral Genetics Genes and Behavior How do genes influence behavior? How does the environment affect what genes do? What is Behavioral Genetics? smart gene found in mice Human behavioral genetics, a relatively new field, seeks to understand both the genetic and environmental contributions to individual variations in human behavior -Human Genome Project Genes as Blueprints Genes represent blueprints for proteins Generally speaking, behavior is caused by the action of proteins Nerve cells Enzymes that produce neurotransmitters or hormones Receptors DNA Protein Behavior RNA gene expression Central Dogma Outline Mutations and Behavior Narcolepsy in humans and dogs Quantitative traits Tameness in foxes Alcoholism Alcohol addiction Caused by alcohol abuse Alcohol dehydrogenase Enzyme that breaks down toxic accumulation of acetaldehyde after consuming alcohol A genetic variant in this gene reduces function of this enzyme and is associated with reduced risk of alcoholism Narcolepsy Excessive daytime sleepiness Abnormal REM sleep Can include sleep paralysis, a condition in which it is not possible to move despite being awake Cataplexy Muscle weakness triggered by emotions Hypnagogic hallucinations Dream-like auditory or visual hal ucinations while dozing or fal ing asleep 2 Narcolepsy: Impact Affects about 1 in 1000 in US, Japan and Europe Drowsiness typically treated with amphetamines Headache, nausea, nervousness, anxiety cataplexy Narcoleptic Dobermans Some Dobermans exhibit behavioral symptoms that are very similar to narcolepsy Using genetic mapping, a single mutation was found to be associated with narcolepsy like symptoms Hypocretin receptor Canine Model of Narcolepsy Hypocretin and Narcolepsy Narcolepsy in humans is not associated with the same mutation seen in dogs Patients with narcolepsy have virtually no hypocretin in postmortem cerebral cortex or pons samples New directions Although the specific mutations in dogs do not directly explain narcolepsy in humans, their discovery sparked new research directions New drugs targeting the hypocretin pathway are now being tested in clinical trials Outline Mutations and Behavior Narcolepsy in humans and dogs Quantitative traits Tameness in foxes Qualitative vs. Quantitative Qualitative: uses categories Small, medium or large Often regulated by a single gene Examples: blood type, Huntingtons disease Quantitative: uses a scale 35 g, 50 g, 100 g Usually regulated by many genes Eye and hair color, personality traits Quantitative traits Quantitative traits Influenced by many genes Variation is quantitative Offspring can have intermediate phenotype relative to parents Complex Inheritance Most behaviors are affected by multiple genes Polygenic trait: a trait affected by multiple genes The more genes that influence a behavioral trait, the more combinations are possible 3...
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- Fall '08