Class_5and6_Behavioral+Genetics

Class_5and6_Behavioral+Genetics - Genes and Behavior...

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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”
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2 Outline • Mutations and Behavior – Narcolepsy in humans and dogs • Quantitative traits – Tameness in foxese 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 hallucinations while dozing or falling asleep 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
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Hypocretin and Narcolepsy • Narcolepsy in humans is not associated with the same mutation seen in dogs • Patients with narcolepsy havevirtually 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 foxese Qualitative vs. Quantitative • Qualitative: uses categories – Small, medium or large – Often regulated by a single gene – Examples: blood type, Huntington’s 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
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This note was uploaded on 11/08/2010 for the course PSC Psychology taught by Professor Cossowings during the Spring '08 term at UC Davis.

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Class_5and6_Behavioral+Genetics - Genes and Behavior...

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