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Recovery from brain damage/injuryDestruction of neurons forces other neurons to take over the lost functions for recoverySurviving neurons can restore functionality by modifying themselves structurally or biochemically oStructurally: sprout new dendrites or extending axons to form new synapsesoBiochemically: release more neurotransmitters Recent findings suggest that brains of mature primates and humans are capable of producing new neurons (neurogenesis)Brain is capable of greater plasticity early in life oBecause 1 to 2 year olds have 50% more brain synapses than mature adults do Unused or weaker synapses deteriorate or suicide with age, so brain loses its plasticity
Genetics – Heritability & Disorders09/12/2013October 10, 2013°Genetics of Behaviour: Nature vs. Nurture °Nature: something we’re born with °Nurture: something we learn Genes: strand-like molecules of DNA that are linked on chromosomes Karyotype: genetic blueprint XY male XX female °Genes (DNA) RNA proteins molecules (sequences of amino acids) °°Protein synthesiscan influence all your attributes. Genes influence protein synthesis, andcan help to determine the range of possibilities – not to what degree you will express them. Thereare no genes for a particular attribute. There is no gene for intelligence, but many people measureintelligence by reaction time. °°Environment can influence protein synthesisas well; environment can contribute to the degree of expression of genes. Environmental exposure at specific interval is critical (i.e. white-crowned sparrow must hear adult song between 7thand 60thday or it will never sing that adult song!!!) Environmental triggers (in critical periods) are important in gene expression. °°Important to distinguish between genotype vs. phenotype: Genotype: set of genes inheritedPhenotype: outward expression of genotype (characteristics, behaviours, etc.) oDominant vs. recessiveOutward characteristics may not indicate underlying genetic contribution. Homozygous (identical) vs. heterozygous alleles (not the same)oHomozygous alleles make genotypic predictions easy
oHeterozygous involves finding dominant and recessive allelesCodominance (i.e. sickle cell anemia) °°Polygenetic Effects: traits related to action of more than 1 gene or chromosome (more than one gene codes for a trait)Recombinant DNA procedures: using certain enzymes to cut long molecules of DNA into pieces, combine them with DNA from other organism and insert them into host organismGene knockout procedure: deactivates one gene to observe effect on behaviour oExample: insert genetic material that will prevent neurons from transmitting serotonin (knockout mechanism for serotonin reuptake), causing very anxious behaviour oProblems: very few behaviours are controlled by on gene, disruption of gene may affect a wide range of functions, and ethical considerations°Calculating heritability: H2 = variance due to genes/ total varianceEstimate of how much observed variability due to genetic aloneH2