Chapter 3 Biology and Behavior I Nature and Nurture A Genetic and Environmental Forces 1 Vocabulary a Genome b Genotype c Phenotype d Environment i The complete set of genes in any organism i Genetic makeup of an individual i Displayed characteristic derived from the genotype i Every aspect of life surrounding an individual other than genes 2 Parent s Genotype Child s Genotype a Vocabulary i Chromosomes Molecules of DNA ii DNA iii Genes Genetic material of an organism Basic unit of heredity Sections of chromosomes b Human heredity c Sex determination i 46 chromosomes in each cell 23 pairs i Males have XY sex chromosomes ii Females have XX sex chromosomes d Diversity and Individuality i Mutation Atypical change in a section of DNA ii Crossing over 3 Child s Genotype Child s Phenotype a Gene expression Developmental changes i Gene environment interaction ii Regulator genes b Gene expression Dominance patterns i Alleles Different forms of the same gene ii Dominant traits override recessive traits iii Polygenic inheritance Process of a segment of DNA switching to another chromosome Genes that control the ebb and flow of other genes processes Several genes contribute to the formation of a character trait or behavior 4 Child s Environment Child s Phenotype a 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 develop b 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 differently c Parental contributions to the child s environment i Parent provided environment depends on parents genetics ii Parenting styles also stem from genes 5 Child s Phenotype Child s Environment a Active child interaction with their development b Children s genetically predisposed behavior promotes certain responses from others B Behavior Genetics c Children actively select surroundings and focus on objects of desire 1 Study of how genetic and environmental factors influence behavior and development 2 Behavior Genetic Research Designs a Family study i Study of various familial relationships and effects on a certain trait comparison of correlations between relationships b Family studies of intelligence i Displayed effect of genetics and environment on IQ 3 Heritability a Statistical estimate of the depth of influence of genetics on a characteristic b Heritability of 75 75 of variation in trait is due to genetic differences c Applies only to populations d Applies only to a particular population living in a particular area at a particular time 4 Environmental Effects a Environment plays very little effect on certain traits b 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 other II Brain Development A Structures of the Brain 1 Neurons a Specialized electrical brain cells b Sensory neurons i Receive sensory stimuli c Motor neurons d i Transmit information from the brain to muscles and glands Interneurons i Intermediaries between sensory and motor neurons ii Located in spinal cord e Structure of a neuron i Dendrites Receive input from other cells ii Cell body iii Axon Contains basic biological material 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 Space between two neurons through which neurotransmitters pass v Synapse 2 Glial Cells a Brain s white matter b Form myelin sheath around neuron axons c nanny cells of the brain 3 The Cortex a 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 Parietal lobe iii 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 areas b 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 Corpus callosum iii Connection between right and left hemispheres B Testing of the Brain 1 Brain imaging can only occur when patients are still a Babies can t be told to stay still b Eliminates MRI or fMRI 2 PET scans 3 EEG ERP 4 Postmortem a Can measure electrical activity in the brain a Ethical but opportunities are very limited C Developmental Processes 1 Neurogenesis and Neuron Development a Cannot inject radioactive material into an infant for research purposes a 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 lifetime c Neurons grow axon first followed by dendrites d Arborization i Increase in size and complexity of the dendrites ii Includes formation of spines Spines increase connectivity with other neurons e 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 Synaptogenesis a Formation of synapses between neurons b As with myelination frontal lobe is last to develop 3 Synapse Elimination a Newborns may experience synesthesia before synaptic pruning takes place b 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 adolescence c Steady increase in grey matter until age 20 or so D The Importance of Experience 1 Plasticity a Ability of the brain to adjust to the environment and experience b Evidence of experience dependent neural change 2 Experience Expectant Processes a Experience expectant plasticity i Brain adjustment to virtually universal experience across the human race ii Fewer genes need to