Chapter 3 Outline
Chapter 3 Outline PSY 2012
Popular in General Psychology
Popular in Psychlogy
This 26 page Class Notes was uploaded by Amanda Martinez on Friday February 5, 2016. The Class Notes belongs to PSY 2012 at University of Florida taught by in Fall 2015. Since its upload, it has received 27 views. For similar materials see General Psychology in Psychlogy at University of Florida.
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Date Created: 02/05/16
Chapter 3: Biological Psychology • Ancient Egyptians believed that the heart was the center of the human soul and the brain was irrelevant to metal life • Greeks said the brain was the source of the psyche o Some were convinced that the brain was only a radiator o Cooling the heart that when it becomes overheated • Ancients correlated that the heart was the center of everything because it speeds up when we get emotional • Today, we know the brain is the most complex structure in the universe o Consistency of gelatin o Weighs 3 lbs o Capable of astonishing feats • Biological psychologists-‐ researchers who study the relationship between the nervous system and behavior o Also called neuroscientists o Bridge multiple levels of analysis within psychology Nerve Cells: Communication Portals • Brain’s most basic form of communication-‐ its cells o Known as neurons Neurons: The Brain’s Communicators • Neurons-‐ nerve cell specialized for communication • Brain’s connect about 85 billion neurons • More than 10x as many neurons to each of our brains as people on Earth • About 160 trillion connections in the human brain • Neurons are shaped differently than other cells o Cell body-‐ aka Soma § Central region of neuron § Manufactures new cell components § Contains nucleus § Damage is fatal § Provides continual renewal of cell components o Dendrites-‐ branch like extensions for receiving information from other neurons § Spread out to “listen in” on conversation from neighboring neurons and pass them on to the cell body o Axons and axon terminals-‐ transmitters § Axon-‐ portion of the neuron that sends signals § Specialized for sending messages to other neurons § Synaptic vesicles-‐ spherical sac containing neurotransmitters • Travel the length of the axon § When it reaches the end of it’s journey to the axon terminal, it releases neurotransmitters-‐ chemical messenger specialized for communication from neuron to neuron o Synapses-‐ space between the two connecting neurons through which the messages are transmitted chemically § Synaptic cleft-‐ a gap into which neurotransmitters are released from the axon terminal • Surrounded by small patches of membrane on each side • Neurotransmitters are picked up quickly by the dendrites of nearby neurons Glial Cells • Glial cells-‐ cell in nervous system that plays a role in the formation of myelin and the blood-‐brain barrier, responds to injury, removes debris, and enhances learning and memory o Astrocytes-‐ interact closely with neurons, increase the reliability of their transmission, control blood flow in the brain, play a vital role in the development of the embryo § Involved in thought, memory and the immune system § Can find them abundantly in the blood-‐brain barrier-‐ protective shield that insulates the brain from infection by bacteria and other intruders o Oligodendrocyte-‐ promotes new connections among nerve cells and releases chemicals to aid in healing § Myelin sheath-‐ glial cells wrapped around axons that act as insulators of the neuron’s signal • Nodes-‐ numerous gaps all the way along the axon o Help the neuron conduct electricity more efficiently o Neural signal jumps from node to node o Clear away debris; brain’s cellular garbage disposal Electrifying Thought • Neurons respond to neurotransmitters by generating electrical activity • Scientists have used electrodes to measure the potential difference-‐ difference in electrical charge inside vs. outside the neuron • All electrical responses depends on an uneven distribution of charged particles across the membrane surrounding the neuron • Resting potential-‐ electrical charge difference (-‐60 millivolts) across the neuronal membrane, when the neuron is not being stimulated or inhibited o No neurotransmitters acting on the neuron o Neuron isn’t doing anything o More negative particles inside than outside the neuron o Particles of both types (+ and -‐) are flowing into and out of the neuron • Threshold-‐ membrane potential necessary to trigger an action potential o Electrical charge inside the neuron reaches a high enough level relative to the outside • Action potentials-‐ electrical impulse that travels down the axon triggering the release of neurotransmitters o Language of neurons; what they use to communicate o Abrupt waves of electric discharge triggered by a change in charge inside the axon o Can describe the neuron as “firing” o All or none law-‐ they either fire or they don’t o Originate in the trigger zone near the cell body o Continue all the way down the axon to the axon terminal o + charged particles flow rapidly into the axon, then flow out just as rapidly, causing a spike in + charge, followed by a decrease in charge o Inside ends with a slightly more negative level than it’s original resting value o Shifts in energy produce a release of electricity o When electrical charge reaches the axon terminal, it triggers the release of neurotransmitters • Neurons can fire extremely rapidly o 100-‐1000 times per second o Energy travels at 220 mph o Absolute refractory period-‐ time during which another action potential is impossible; limits maximal firing rate § Follows each action potential Chemical Communication: Neurotransmission • Chemical events triggered by neurotransmitters cause communication among neurons • Receptor sites-‐ location that uniquely recognizes a neurotransmitter o Where neurotransmitters bind after they are released into the synapse o Found on dendrites of neighboring neurons o Lock and key formation • Can be halted by reuptake-‐ means of recycling neurotransmitters o Synaptic vesicle reabsorbs the neurotransmitter • Glutamate and GABA: o Most common neurotransmitters in the CNS o Neurons in virtually every brain area use these 2 chemical messengers to communicate with each other o Glutamate-‐ rapidly excites neurons § Enhanced learning and memory § Elevated-‐ schizophrenia and other mental disorders o GABA-‐ inhibits neurons, dampening neural activity § Suppress overactive areas in the brain § Plays critical roles in learning, memory and sleep § Scientists want to create drugs that target GABA to treat anxiety, insomnia, depression and epilepsy • Acetylcholine: o Plays roles in arousal, selective attention, sleep and memory o Alzheimer’s-‐ neurons containing acetylcholine are destroyed leading to memory loss o Medications boost acetylcholine levels in the brain o Neurons that connect to muscles release acetylcholine to trigger movement • Monoamines: o Norepinephrine, dopamine and serotonin o Only contain 1 amino acid o Dopamine-‐ critical role in rewarding experiences that occur when we seek out or anticipate goals o Norepinephrine and serotonin activate or deactivate various parts of the brain § Influence arousal and readiness to respond to stimuli • Anandamide: o Cells make anandamide, which binds to the same receptors as THC o Plays roles in eating, motivation, memory and sleep o May explain why marijuana makes people hungry and sleepy • Neuropeptides: o Short strings of amino acids o More narrowly targeted in their jobs o Endorphins-‐ chemical in the brain that plays a specialized role in pain reduction o Our brains contain their own receptors for endogenous opioids § Morphine o Human made endorphins hijack the endorphin system, binding to endorphin receptors and mimicking their effects o Some neuropeptides regulate hunger and satiety, and others learning and memory • Drugs that interact with neurotransmitter systems are called psychoactive o Affect mood, arousal and behavior • Opiates function as agonists-‐ increase receptor site activity o Codeine and morphine o Reduce emotional response to painful stimuli o Mimic endorphins • Antagonists-‐ decrease receptor site activity o Act as “fake neurotransmitters” fooling receptors into thinking they are dopamine without exerting the effects of the neurotransmitter Neural Plasticity: How and When the Brain Changes • Plasticity-‐ ability of the nervous system to change • Few human behaviors are hardwired • Nervous system is continually changing as we learn • Doesn’t change enough followed by injury or stroke o Can lead to paralysis or disability • Brain is most flexible during early development • Network of neurons changes over the course of development in 4 primary ways o Growth of dendrites and axons o Synaptogenesis, the formation of new synapses o Pruning, consisting of the death of certain neurons and the retraction of axons to remove connections that aren’t useful o Myelination, the insulation of axons with the myelin sheath § Pruning is the most surprising § As many as 70% of all neurons die off § Streamlines neural organization § Our brains can process info more efficiently with fewer neurons • Our brains change as we learn o Result from the formation of new synapses § Generate increased connections and communication among neurons § Strengthening of existing synaptic connections • Stronger and prolonged response from neighboring neurons • Known as potentiation o Structural plasticity-‐ change in the shape of neurons § Critical for learning o Exposure to enriched environments also results in structural enhancements to dendrites • Brain and spinal chord display limited regeneration after injury or illness • Certain brain regions can take over functions previously performed by others • Neurogenesis-‐ creation of new neurons in the adult brain o Odds are high that neurogenesis occurs in adult brains o By triggering it, scientists might one day be able to induce the adult nervous system to heal itself o May also pay a role in learning • Stem cells-‐ a cell, often originating in embryos, having the capacity to differentiate into a more specialized cell o Haven’t committed themselves to a specific function o Offer several ways of treating diseases marked by neural degeneration § Can implant stem cells directly into the host’s nervous system and induce them to grow and replace damaged cells § Genetically engineer stem cells to provide gene therapy o Controversial § Advocates praise its potential for treating serious diseases § Opponents say research requires investigators to create and extract lab-‐ created balls of cells that are 4-‐5 days old • Early form of human life The Brain-‐Behavior Network • Connections among neurons provide physiological bases of our thoughts, emotions and behaviors • Central Nervous System (CNS)-‐ part of the nervous system containing the brain and spinal cord that controls the mind and behavior o Sensory information • Peripheral Nervous System (PNS)-‐ nerves in the body that extend outside the CNS o Somatic nervous system-‐ voluntary behavior o Autonomic nervous system-‐ nonvoluntary functions of the body § Automatic § Controls behaviors that occur outside of our conscious awareness The Central Nervous System: The Command Center • Brain and spinal cord are protected by meninges-‐ three thin layers of membranes • Cerebral ventricles-‐ pockets in the brain that contain cerebrospinal fluid (CSF), which provide the brain with nutrients and cushion against injury o CNS’s shock absorber • Cerebral cortex-‐ outermost part of forebrain, responsible for analyzing sensory processing and higher brain function o Outermost part of the cerebrum o Cortex = “bark” § Surrounds the hemispheres like bark on a tree o Contains 4 regions called lobes § Each associated with somewhat different functions • Cerebrum (forebrain)-‐ forward part of the brain that allows advanced intellectual abilities o Most highly developed area of the human brain o 12-‐20 billion neurons o Consists of 2 cerebral hemispheres-‐ 2 halves of the cerebral cortex, each of which serve distinct yet highly integrated functions § Look alike but serve different functions • Corpus callosum-‐ large band of fibers connecting the 2 cerebral hemispheres o Means “colossal body” in Latin • 4 Lobes: o Frontal lobe-‐ forward part of the cerebral cortex responsible for motor function (movement), language, memory and planning § Executive functioning-‐ overseeing and organizing most other brain functions § Central sulcus-‐ deep groove; separates frontal lobe from the rest of the cortex § Motor cortex-‐ part of the frontal lobe responsible for body movement • Lies next to central sulcus and is part of frontal lobe • Each part controls a specific part of the body • Initiates movement, which is then passed on to the cerebellum for finer details § Prefrontal cortex-‐ part of the frontal lobe responsible for thinking, planning and language • Broca’s area-‐ language area in the prefrontal cortex that helps to control speech production o Formation of speech o Damage = can’t speak • Also contributes to mood, personality and self-‐awareness o Parietal lobe-‐ upper middle part of the cerebral cortex lying behind the frontal lobe that is specialized for touch and perception § Back region is the primary sensory cortex • Sensitive to touch, pressure, pain and temperature § Helps us track objects locations, shapes and orientations § Helps us process others’ actions and represent numbers § Relays visual and touch info to the motor cortex § Damage results in trouble making sense of their immediate surroundings • Neglect of the opposite side of the body where the damage happened o Temporal lobe-‐ lower part of the cerebral cortex that plays roles in hearing, understanding language and memory § Separated from the rest of the cortex by the lateral fissure § Top contains auditory cortex-‐ devoted to hearing § Wernicke’s area-‐ part of the temporal lobe involved in understanding speech • Damage results in difficulties understanding speech • Damaged patients speak gibberish § Lower part is critical for storing memories o Occipital lobe-‐ back part of the cerebral cortex specialized for vision § Contains visual cortex § We have more of our brain dedicated to the visual cortex because we rely strongly on visual imputs • When info from the outside world is transmitted by a specific sense, it reaches our primary sensory cortex-‐ regions of the cerebral cortex that initially process info from the senses • It’s then passed to the association cortex-‐ regions of the cerebral cortex that integrate simpler functions to perform more complex functions o Most of the cerebrum (about ¾) consists of association cortex o Much of what makes us smart relies on integrating (associating) info across different brain areas o Association cortex synthesizes info to perform more complex functions o Overall organization is hierarchical § Processes become increasingly complex as info passes up the network • Basal ganglia-‐ structures in the forebrain that help to control movement o Buried deep in the cortex and help control movement o Damage = Parkinson’s disease o Sensory info is transmitted to the basal ganglia after the primary and association cortexes § Calculate a course of action and transmit it to the motor cortex o Allows us to perform movements to obtain rewards • Limbic system-‐ emotional center of brain that also plays roles in smell, motivation and memory o Processes info about internal states o Thalamus-‐ gateway from the sense organs to the primary sensory cortex § Connects many areas which connect to a specific region of the cerebral cortex § Sensory relay station o Hypothalamus-‐ part of the brain responsible for maintaining a constant internal state § Means “below the thalamus” § Different areas play various roles in emotion and motivation § Helps regulate hunger, thirst, sexual motivation and other emotional behaviors § Assists with controlling body temp. o Amygdala-‐ part of the limbic system that plays key roles in fear, excitement and arousal § Plays key role in fear conditioning o Hippocampus-‐ part of the brain that plays a role in spatial memory § Spatial memory-‐ memory of a physical layout of things in our environment § Make a mental map = using out hippocampus § Damage = problems forming new memories • Leaves old memories intact • Cerebellum-‐ brain structure responsible for our sense of balance o Latin for “little brain” o Mini version of the cortex o Enables us to coordinate movement and learn motor skills § Performs actions received by motor cortex o Contributes to executive, memory, spatial and linguistic abilities o Damage = balance problems • Brain stem-‐ part of the brain between the spinal cord and cerebral cortex that contains the midbrain, pons and medulla o Performs basic bodily functions that keep us alive o Midbrain-‐ part of the brain stem that contributes to movement, tracking of visual stimuli and reflexes triggered by sound o Reticular activating system (RAS)-‐ brain area that plays a key role in arousal § Connects forebrain with cerebral cortex § Damage = COMA § Pathways activate the cortex by jacking up the signal-‐to-‐noise ratio among neurons in the brain o Hindbrain-‐ region below the midbrain that contains the cerebellum, pons and medulla o Pons-‐ part of the brain stem that connects the cortex with the cerebellum o Medulla-‐ part of the brain stem that connects the cortex with the cerebellum § Regulates breathing, heartbeat and other vital functions § Controls nausea and vomiting § Damage = brain death • Irreversible coma • Totally unaware of surroundings and unresponsive • No signs of spontaneous movement, respiration or reflex activity • Often confused with persistent vegetative state (cortical death) o Spinal cord-‐ thick bundle of nerves that conveys signals between the brain and body § Extends from brain stem, runs down middle of our backs, conveying info between the brain and the rest of the body § Nerves extend from neurons to the body • Travel 2 directions • Sensory nerves-‐ carry sensory info from the body to the brain • Motor nerves-‐ carry motor commands from the brain to the body § Interneurons-‐ neuron that sends messages to other neurons nearby • Connect sensory nerves with motor nerves within the spinal cord without having to report to the brain • Reflexes-‐ automatic motor response to a sensory stimulus The Peripheral Nervous System • Consist of nerves that extend outside of the CNS • Somatic nervous system-‐ part of the nervous system that conveys info between the CNS and the body, controlling and coordinating voluntary movement o Carries info to muscles • Autonomic nervous system-‐ part of the nervous system controlling the involuntary actions of our internal organs and glands, which (along with the limbic system) participates in emotion regulation o Sympathetic nervous system-‐ division of the autonomic nervous system engaged during a crisis or after actions requiring fight or flight § Active during emotional arousal, especially crisis § Fight or flight-‐ increased heart rate, respiration and perspiration o Parasympathetic nervous system-‐ division of the autonomic nervous system that controls rest and digestion § Kicks into gear when there’s no threat on our mental radar screens The Endocrine System • Endocrine system-‐ system of glands and hormones that controls secretion of blood-‐ borne chemical messengers • Hormones-‐ chemical released into the bloodstream that influences particular organs and glands o Much slower than neurotransmitters because they’re carried through the bloodstream o Outlast neurotransmitters in their effects Pituitary Gland and Pituitary Hormones • Pituitary gland-‐ master gland that, under the control of the hypothalamus, directs the other glands of the body • Once called “master gland” • Releases a variety of hormones that serve numerous functions o Physical growth, controlling blood pressure, determining how much water we retain in our kidneys • Oxytocin-‐ responsible for several reproductive functions o Stretching the cervix and vagina during birth o Aiding milk flow in nursing mothers o Plays essential roles in maternal and romantic love o “love molecule” o Influences how much we trust each other The Adrenal Glands and Adrenaline • Adrenal glands-‐ tissue located on top of the kidneys that releases adrenaline and cortisol during states of emotional arousal • Emergency centers of the body • Adrenaline-‐ boosts energy production in muscle cells, while conserving as much energy as possible o Contraction of our heart muscle and constriction of our blood vessels to provide more blood to the body o Opening the bronchioles of the lungs to allow inhalation of more air o Breakdown of fatty acids, providing us with more fuel o Breakdown of glycogen into glucose to energize our muscles o Opening the pupils of our eyes to enable better sight during emergencies o Inhibits gastrointestinal secretions o Allows people to perform amazing feats in crisis situations § Constrained by people’s physical limitations o Pleasurable and exciting activities also produce adrenaline rushes • Cortisol-‐ increases in response to physical and psychological stressors o Anxiety disorders = elevated levels of cortisol o Conduct problems = low levels of cortisol o Regulates blood pressure and cardiovascular function o Regulates body’s use of proteins, carbs and fats o Regulates body weight Sexual Reproductive Glands and Sex Hormones • Testes in males • Ovaries in females • Testosterone-‐ male sex hormone; made by testes • Estrogen-‐ female sex hormone; made by ovaries • Both sexes manufacture some amount of sex hormone associated with the opposite sex o Women produce 1/20 the amount of testosterone of males o Ovaries and adrenal glands make testosterone o Testes manufacture low levels of estrogen Mapping the Mind: The Brain in Action • We know more about the brain today than we did 200 or even 20 years ago because of psychologists and related scientists who’ve developed many methods to explore the brain and its functions A Tour of Brain-‐Mapping Methods • Phrenology-‐ one of the first attempts to map the brain o Phrenologists assessed bumps on the head and attributed various personality and intellectual characteristics o Assumed enlargements corresponded to brain enlargements linked to psychological capacities o Founder of phrenology-‐ Franz Joseph Gall o Based hypotheses about supposed associations between brain areas and personality traits on anecdotal observations o Researchers discovered that patients with damage to specific brain areas didn’t experience the kinds of psychological deficits the phrenologists predicted • New methods arose to full the void left by phrenology o Studying psychological functioning following damage to specific brain regions • Created lesions in animals • Neuropsychologists rely on sophisticated psychological tests o Tests measure reasoning, attention, verbal and spatial ability o Require specialized training to administer, score and interpret o Lab, computerized and paper-‐and-‐pencil measures assess patients’ cognitive strengths and weaknesses • Researchers discovered that stimulating parts of the human motor cortex produced specific movements o Led to hypothesis that neurons use electrical activity to send info • Electroencephalograph (EEG)-‐ recording of brain’s electrical activity at the surface of the skull o Patterns and sequences allow scientists to infer whether a person is awake or asleep, dreaming or not and to tell which regions are active during specific tasks o Researchers record electrical activity from multiple electrodes placed on the scalp’s surface o Non-‐invasive o Tell us little about what is happening inside the neurons • Computed tomography (CT)-‐ a scanning technique using multiple X-‐rays to construct 3-‐D images o Displays far more detail than an X-‐ray • Magnetic resonance imaging (MRI)-‐ technique that uses magnetic fields to indirectly visualize brain structure o Measures the release of energy from water in biological tissues following exposure to a magnetic field o Superior to CT scans for detecting soft tissues § I.e. brain tumors • Positron emission tomography (PET)-‐ imaging technique that measures consumption of glucose-‐like molecules, yielding a picture of neural activity in different regions of the brain o Functional imaging technique o Measures changes in brain’s activity in response to stimuli o Basic principle: neurons increase their intake of glucose when they’re active o PET requires the injection of radioactive glucose-‐like molecules into patients § Short lived so they do little to no harm o Scanner measures where in the brain most of the glucose-‐like molecules are gobbled up • Functional MRI (fMRI)-‐ technique that uses magnetic fields to visualize brain activity using changes in blood oxygen levels o Indirect indicator of neural activity o Provides detailed images of activity in small brain regions over brief time intervals o Extremely sensitive to motion • Transcranial magnetic stimulation (TMS)-‐ applies strong and quickly changing magnetic fields to the skull that can either enhance or interrupt brain function o Offers useful insights about which brain areas are involved in different psychological processes o Only non-‐invasive brain imaging technique that allows us to infer causation • Magnetoencephalography (MEG)-‐ technique that measures brain activity by detecting tiny magnetic fields generated by the brain o Reveals patterns of magnetic fields on the skull’s surface o Measures brain changes millisecond by millisecond • Extremely easy to misinterpret brain scans How Much of Our Brain Do We Use? • William James wrote that most people fulfill only a small % of their intellectual potential • Some people misunderstood it to mean we only use 10% of our brain Which Parts of Our Brain Do We Use for What? • Localization of function-‐ brain areas that are active during a specific psychological task over and above a baseline rate of activity Which Side of Our Brain Do We Use for What? • Many capacities rely on one cerebral hemisphere more than the other • Lateralization-‐ cognitive function that relies more on one side of the brain than the other • Roger Sperry proved that the 2 hemispheres serve different functions • Split-‐brain surgery-‐ procedure that involves severing the corpus callosum to reduce the spread of epileptic seizures o Patients experience a bizarre fragmenting of mental functions that most of us normally experience as integrated o Experience difficulties integrating info presented to separate hemispheres • Possible to only live with half a brain Nature and Nurture: Did Your Genes – or Parents – Make You Do It? • Our nervous system is shaped by both our genes (nature) and our environment (nurture) How We Come to Be Who We Are • Chromosomes-‐ slender thread inside a cell’s nucleus that carries genes • Genes-‐ genetic material, composed of deoxyribonucleic acid (DNA) • Genotype-‐ our genetic makeup • Phenotype-‐ our observable traits o Shaped by environmental factors • Can’t easily infer people’s genotypes by observing their phenotypes • Some genes are dominant-‐ gene that masks other genes’ effects • Recessive-‐ gene that is expressed only in the absence of a dominant gene • On the Origin of Species by Charles Darwin introduced his theory of evolution by natural selection o Populations of organisms change gradually over time o Some organisms possess adaptations that make them better suited to their environments o They survive and reproduce at higher rates than the other organisms o These are more likely than others to pass on their genes to future generations o Fitness-‐ organisms’ capacity to pass on their genes • Proportional to our body size, we’re the biggest brained animals • Relative brain size is associated with behaviors we typically regard as intelligent o Big-‐brained animals tend to have large and complex social networks Behavioral Genetics: How We Study Heritability • Examine the influence of nature and nurture on psychological traits • Heritability-‐ percentage of variability in a trait across individuals that is due to genes o Height is highly heritable; due to different genes o Heritability of religion is low; due to environmental factors • Reaction range-‐ extent to which genes set limits on how much a trait can change in response to new environments • Family studies-‐ analysis of how characteristics run in intact families o Useful in estimating the risk of a disorder among the relatives of people afflicted with that disorder o Drawback-‐ relatives share a similar environment as well as similar genetic material o Don’t allow us to disentangle the effects of nature from nurture • Twin studies-‐ analysis of how traits differ in identical versus fraternal twins o Identical twins are more similar genetically than are fraternal twins o If identical twins are more alike on psychological characteristics, then we can infer that this characteristic is genetically influenced § Environmental influences must be the same for both sets of twins • Adoption studies-‐ analysis of how traits vary in individuals raised apart from their biological relatives o Examine the extent to which children adopted into new homes resemble their adoptive parents as opposed to their biological parents o If they resemble their biological parents, its genetically influenced o Selective placement-‐ placing children in homes similar to those of their biological parents o Investigators can mistakenly interpret the similarity between adopted children and their biological parents as genetic
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