PSY201H - Chapter 3 Biology of Behavior
PSY201H - Chapter 3 Biology of Behavior PSY 201H
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This 8 page Class Notes was uploaded by Brandon Harvey on Sunday October 16, 2016. The Class Notes belongs to PSY 201H at Marshall University taught by Dr. Fugett in Fall 2016. Since its upload, it has received 3 views. For similar materials see General Psychology Honors in Psychology at Marshall University.
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Date Created: 10/16/16
Chapter 3 Biology of Behavior Genes and Behavior o Chromosomes o DNA o Genes Genome Alleles Mutations Dominant genes: show effect even if there is only one copy of that allele Recessive genes: only show if both alleles are identical o Behavioral genetics Four principles The relationship between specific genes and behavior is complex Most specific behaviors derive from dozens or hundreds of genes – not one or two By studying twins and adoptees, behavioral geneticists may disentangle the contributions of heredity and environment that influence behavior The environment influences how and when genes affect behavior Complex Connection Between Genes and Behavior o Genes seldom make behaviors certainty o Genes and environment make anxiety more likely o Huntington’s disease (incurable neuromuscular disease) is genetic o Environmental events (smoking during pregnancy, childhood experiences, stress or trauma, and enriched environments) interact with genes to make specific behaviors more or less likely Polygenic Influence on Behavior o Few traits are from a single gene o Monogenic: traits determined by a single gene Huntington’s disease o Genes contribute to intelligence o Polygenic: traits determined by the interaction of many genes Skin color Mental disorders Personality (adventurous, etc.) Height Weight Genes and the Environment o Teasing apart and identifying genetic and environmental influences on behavior require special techniques o Heritability: the extent to which a characteristic is influenced by genetics o Twin-Adoption Studies Fraternal twins: develop from two different eggs, fertilized by two different sperm; genetically different like nontwin siblings - ~50% Identical twins: develop from a single fertilized egg, which splits into two independent cells; two embryos with identical genetic information – 100% Twin-adoption studies: research into hereditary influence on twins, both identical and fraternal, who were raised apart (adopted) and who were raised together Adopted children and adoptive parents share no genetic information Greater genetic similarity, should lead to greater similarity on trait Similarity strongest in identical twins reared together and next in identical twins reared apart Similarity hold this pattern for intelligence, mental disorders, personality, suggesting moderately strong genetic components o Gene-by-Environment Studies Allows researchers to assess how genetic differences interact with the environment to produce certain behavior in some people but not others Directly measure genetic variation in parts of the genome itself, and examine how such variation interacts with different kinds of environments to produce different behaviors Individuals differ in the form, or allele, a gene takes Genetic marker Interact with stressful environment to make depression more likely in some (short DNA) than in others (long DNA) Epigenetics o Study of changes in the way genes are expressed o Methylation Turning “off” of genes when methyl group attaches to sequence, cytosine in particular o Identical twins do not have identical fingerprints Organization of Nervous system o CNS Brain and spinal chord o PNS All other nerve cells Somatic (voluntary) nervous system Body sensations, voluntary movement Transmits sensory information to the brain and spinal cord and from the brain and spinal cord to the skeletal muscles Autonomic (involuntary) nervous system Internal organs and glands Sympathetic nervous system o Fight or flight o Arousing Parasympathetic nervous system o Relaxation o Calming Cells of the Nervous System o Glial cells The “glue” that hold the CNS together Insulation (myelin sheath) Blood brain barrier Metabolism Regulation of neuron transmission o Neurons Cells that process and transmit information in the nervous system Three major principles of neuroscience Neurons are building blocks of nervous system and comprise brain structures Information travels within a neuron in form of electrical signal by action potentials Information is transmitted between neurons by neurotransmitters Dendrites, Soma, Axon, Terminal buttons – sacs of neurotransmitters Types Sensory o Receives information from sensory organs (eyes, ears, mouth, nose, skin) Motor o Carry commands for muscle movement o Mirror neurons: muscle memory (partially) active when we observe others performing an action as well as when we are performing the same action “monkey see, monkey do” Interneurons o Communicate only with other neurons o Most common o Implicated in over excitation in brain for epilepsy, and schizophrenia Neurotransmitters o Acetylcholine Muscle movement Learning Memory Sleeping Dreaming Alzheimer’s disease: o lower Acetyl levels o Dopamine Voluntary movement Reward anticipation Pleasure Cocaine: o Blocks reuptake (reuptake: neurotransmitters taken back into vesicle in terminal button) o Epinephrine (adrenaline) Energize Arouse Tends not to affect mental status o Norepinephrine Increases mental arousal, alertness Increases physical arousal ADHD: o Lower norepinephrine levels o Serotonin Dreaming Attention Learning Depressions/anxiety & anger/aggression: o Low serotonin levels Ecstasy (MDMA): o High serotonin levels o Interferes with brain’s ability to produce serotonin SSRI’s drugs to increase serotonin levels by blocking reuptake o GABA Inhibitory (tell postsynaptic neurons “Do NOT fire!” Regulation Slows CNS Control Alcohol: o High GABA levels, relaxing, uncoordinated o Glutamate Excitatory Learning, memory, selective attention Facilitate neural development Nicotine: o interferes with neural development Overview of Brain Regions o Forebrain Collectively control cognitive, sensory, and motor function and regulate temperature, reproductive functions, eating, sleeping, and the display of emotions. Bilateral (two of each – one on each side) Thalamus Receives input from ears, eyes, skin, or taste buds and relays sensory information to the appropriate part of cerebral cortex Sensory relay station Does not receive olfactory information Limbic system Middle of brain Emotion and motivation Debate over whether system is actually a “system” Hypothalamus o Below thalamus o Regulates almost all of major drives and motives: hunger, thirst, temperature, sexual behavior o Controls pituitary gland: produces and controls hormones Hippocampus o Wraps around thalamus o Sensory information from sense organs o Learning, selection for lasting memory o Most open to change Amygdala o Small, almond shape in front of hippocampus o Connects with many areas of brain Hypothalamus ANS Hippocampus Memory Thalamus Sense organs Cerebral cortex o Emotional significance of stimuli, especially fear Cingulate gyrus o Belt like in middle o Front part plays role in attention and cognition o Problem solving o Schizophrenia Basal ganglia o Collection of structures around both sides of thalamus, above limbic system, connect with cerebral cortex, thalamus, and brainstem o Voluntary motor control o Parkinson’s and Huntington’s disease Responsible for dopamine (rewards) and dementia/Alzheimer Smell and connection to memory Cerebrum o Hindbrain Directly connected to spinal cord Regulate breathing, heart rate, arousal, and other basic survival functions Pons – “bridge” between lower brain regions and higher midbrain and forebrain activity; body movement and various sensations relayed from cortex via pons to cerebellum Cerebellum – “little brain”; body movement, balance, coordination, and fine motor skills e.g. typing and playing piano; important in cognitive actions such as learning and language Medulla – extends directly from spinal cord; regulate breathing, heart rate, and blood pressure; involved in various reflexes e.g. coughing, sneezing, swallowing, and vomiting o Midbrain Smallest Control eye muscles, process auditory and visual information, initiate voluntary movement of body Parkinson’s disease Brainstem – midbrain, medulla, and pons reticular formation: network of nerves that runs through midbrain and hindbrain, and plays a key role in wakefulness Cerebrum and Cerebral Cortex o Cerebral cortex: outer layer and convolutions Human thought, planning, perception, and consciousness o Cerebrum: Upper most portion of the brain; folded into convolutions, divided into two large hemispheres, and composed of four bilateral lobes Four lobes Frontal o Primary motor cortex (back part of the lobe left fissure between frontal and parietal) o Planning, impulse control, abstract thinking, etc. o Phineas Gage Parietal o Somatosensory cortex (touch) (front part of lobe, just right of fissure) o Parallels the Motor Cortex Temporal o Auditory cortex (hearing) o Memory, emotion Occipital o Primary Visual Cortex Insula: small structure deep inside cerebrum and separates temporal and parietal lobes; active in perception of bodily sensations, emotional states, empath and addictive behavior Two hemispheres Different processions styles o Right – insight and solutions to ideas; holistic o Left – analytical and focused Aphasia (language) – disorder of language (lesion of areas of the brain) – mainly seen in stroke victims, concussions Broca’s area (left frontal/temporal) o Speech production o Patient aware of what they want to say, but cannot find a word to make a sentence. Mostly verbal, but also written. Know what they want to say, and are aware of their disorder. Frustrating to patient. Wernicke’s area (temporal) o Speech comprehension o People say things and do not make any sense. “Word salad.” Unaware that you have this disorder. Corpus Callosum o Thick bundle of nerve fibers that connect the two hemispheres; cutting corpus callosum stops communication between hemispheres. Communication Between the Hemispheres o Activity across the corpus callosum allows hemispheres to communicate/collaborate Right visual field – goes to left side of brain – speech/writing Left visual field – goes to right side of brain – comprehension Brain Plasticity and Neurogenesis o Principles of brain plasticity Neuroplasticity Ability to adopt new functions Reorganize existing functions Make new neural connection throughout life as a function of experience Almost every major structure of neuron is capable of experience based change Experience-based change o Things that fire together, wire together – synaptogenesis (learning) – formation of new connections with other neurons o Occurs throughout the brain and throughout life o Neurogenesis (new cells) o Arborization (new dendrites) Plasticity varies for different parts of brain Plasticity varies for different ages; strongest in infancy and gradually decreases Blind/deaf people better at processing peripheral senses Endocrine System o System of glands that secrete and regulate hormones o Hormone: chemicals, secreted by glands, that travel in the bloodstream and carry messages to tissues and organs all over the body. o Pituitary gland: the master endocrine gland of the body; controls the release of hormones from glands throughout the body. Thyroid – metabolism Pancreas – blood sugar levels Ovaries/testes – sex hormones o Adrenal glands: sit on top of kidneys and regulate stress o Catecholamine: chemicals released from the adrenal glands that function as hormones and as neurotransmitters to control ANS activation. o Cortisol: a stress hormone produced by the body to ensure that the body gets enough fuel during emotional arousal and stress.
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