Chapter 3: Biology and BehaviorI. Nature and NurtureA. Genetic and Environmental Forces1) Vocabularya) Genome(i) The complete set of genes in any organismb) Genotype(i) Genetic makeup of an individualc) Phenotype(i) Displayed characteristic derived from the genotyped) Environment(i) Every aspect of life surrounding an individual other than genes2) Parent’s Genotype-Child’s Genotypea) Vocabulary(i) Chromosomes- Molecules of DNA(ii) DNA- Genetic material of an organism(iii) Genes- Basic unit of heredity- Sections of chromosomesb) Human heredity(i) 46 chromosomes in each cell (23 pairs)c) Sex determination(i) Males have XY sex chromosomes(ii) Females have XX sex chromosomesd) Diversity and Individuality(i) Mutation- Atypical change in a section of DNA(ii) Crossing over- Process of a segment of DNA switching to another chromosome3) Child’s Genotype-Child’s Phenotypea) Gene expression: Developmental changes(i) Gene-environment interaction(ii) Regulator genes- Genes that control the ebb and flow of other genes’ processesb) Gene expression: Dominance patterns(i) Alleles- Different forms of the same gene(ii) Dominant traits override recessive traits(iii) Polygenic inheritance- Several genes contribute to the formation of a character trait or behavior4) Child’s Environment-Child’s Phenotypea) Norm of reaction(i) All phenotypes that may result from a given genotype in relation to all the environments in which it can survive and developb) Examples of genotype-environment interaction(i) Genetically identical organisms can develop different characteristics depending on environment interaction(ii) Phenylketonuria (PKU)- No significant defects if diet is restricted(iii) Abusive parenting- Different individuals in the same environment react differentlyc) Parental contributions to the child’s environment(i) Parent-provided environment depends on parents’ genetics(ii) Parenting styles also stem from genes5) Child’s Phenotype-Child’s Environmenta) Active child interaction with their developmentb) Children’s genetically predisposed behavior promotes certain responses from othersc) Children actively select surroundings and focus on objects of desireB. Behavior Genetics1) Study of how genetic and environmental factors influence behavior and development2) Behavior Genetic Research Designsa) Family study(i) Study of various familial relationships and effects on a certain trait & comparison of correlations between relationshipsb) Family studies of intelligence(i) Displayed effect of genetics and environment on IQ3) Heritabilitya) Statistical estimate of the depth of influence of genetics on a characteristicb) Heritability of 75%: 75% of variation in trait is due to genetic differencesc) Applies only to populationsd) Applies only to a particular population living in a particular area at a particular time4) Environmental Effectsa) Environment plays very little effect on certain traitsb) Birth order(i) Oldest child reared by “different” parents than youngest(ii) Parents behave toward different children differently(iii) Siblings may strive to differentiate themselves from each otherII. Brain DevelopmentA. Structures of the Brain1) Neuronsa) Specialized electrical brain cellsb) Sensory neurons(i) Receive sensory stimulic) Motor neurons(i) Transmit information from the brain to muscles and glandsd) Interneurons(i) Intermediaries between sensory and motor neurons(ii) Located in spinal corde) Structure of a neuron(i) Dendrites- Receive input from other cells(ii) Cell body- Contains basic biological material(iii) Axon- Longest portion of a neuron- Conducts signals away from cell body to terminal- Covered in myelin sheath Increases conductance rates(iv)Axon terminals- Sending portion of neuron- Neurotransmitters sent out in vesicles from axon terminals(v) Synapse- Space between two neurons through which neurotransmitters pass2) Glial Cellsa) Brain’s white matterb) Form myelin sheath around neuron axonsc) “nanny” cells of the brain3) The Cortexa) Cerebral cortex(i) Occipital lobe- Located near the nape of one’s neck- Involved in processing visual information and vital functions(ii) Temporal lobe- Located near both temples- Involved in processing auditory information, memory, and emotion(iii) Parietal lobe- Located at the crown of the head- Involved in spatial and somatosensory processing(iv)Frontal lobe- Located behind forehead- Involved in executive functions(v) Association areas- Located between major sensory and motor areasb) Cerebral lateralization(i) Specialization of the hemispheres of the brain for different modes of processing(ii) Hemispheres- Left Arithmetic Rhythm Sense of time Language Speech Writing Ordering of complex movements- Right Perception Spatial skills Visualization Emotion Recognition of faces, patterns, melodies Simple language comprehension(iii) Corpus callosum- Connection between right and left hemispheresB. Testing of the Brain1) Brain imaging can only occur when patients are stilla) Babies can’t be told to stay stillb) Eliminates MRI or fMRI2) PET scansa) Cannot inject radioactive material into an infant for research purposes3) EEG/ERPa) Can measure electrical activity in the brain4) Postmortema) Ethical, but opportunities are very limitedC. Developmental Processes1) Neurogenesis and Neuron Developmenta) Creation of new neurons through mitosis (cell division)b) Complete by 18 weeks after conception(i) But adult neurogenesis does continue(ii) Presence of stem cells throughout lifetimec) Neurons grow axon first, followed by dendritesd) Arborization(i) Increase in size and complexity of the dendrites(ii) Includes formation of spines- Spines increase connectivity with other neuronse) Myelinization(i) Formation of myelin sheaths around axons by glial cells(ii) Completed in different areas of the brain at different times (frontal lobe last)2) Synaptogenesisa) Formation of synapses between neuronsb) As with myelination, frontal lobe is last to develop3) Synapse Eliminationa) Newborns may experience synesthesia before synaptic pruning takes placeb) Synaptic pruning(i) 40% of total synapses are pruned(ii) Process of eliminating unnecessary synapses(iii) First large-scale pruning follows birth(iv)Second pruning occurs during adolescencec) Steady increase in grey matter until age 20 or soD. The Importance of Experience1) Plasticitya) Ability of the brain to adjust to the environment and experienceb) Evidence of