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FAU / Psychobiology / PSB 4240 / What is the cerebral cortex?

What is the cerebral cortex?

What is the cerebral cortex?

Description

School: Florida Atlantic University
Department: Psychobiology
Course: Neuropsychology
Professor: Edward ester
Term: Fall 2017
Tags:
Cost: 50
Name: PSB 4240 Exam 1 Study Guide
Description: Study guide covers chapters 1 through 6, but excludes chapter 2 because that information was not significant for the exam
Uploaded: 09/22/2017
10 Pages 185 Views 8 Unlocks
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1


What is the cerebral cortex?



Exam 1 Study Guide (Chapters 1 – 6)

Chapter 1 

∙ Brain hypothesis – brain is tissue found within skull/cranium

o Brain – composed of two symmetrical hemispheres (halves), which are connected by  commissures (example: corpus callosum connects brain’s hemispheres)

▪ Interior of brain contains four hollow ventricles filled with CSF, which  

cushions brain and assists in removing metabolic waste

o Cerebral cortex – outer layer of wrinkled tissue

▪ Gyri – folds/bumps in cortex, top/flat parts

▪ Sulci – creases between folds/gyri; large sulci – fissures

▪ The cortex of each hemisphere forms four lobes – frontal, temporal, parietal,  occipital


Spinal cord is connected to what?



o Brain further divided into different segments

▪ Forebrain – cerebral cortex; performs higher functions such as thinking,  

perception, planning

▪ Brainstem – subcortical structures such as thalamus, BG, cerebellum, etc.;  performs regulatory and movement-producing functions Don't forget about the age old question of What are the two types of residential architecture?

▪ Spinal cord (SC) – connected to brainstem and descends down back; conveys  sensory information to brain and sends commands from brain telling muscles  to move

o CNS – brain and SC; skull protects brain, vertebrae protect SC; does NOT regenerate  lost tissue

o PNS – fibers that carry information to and from CNS; tissue CAN regenerate after  damage If you want to learn more check out Who calculates the cost of a product?

▪ Somatic NS (SNS) – sensory and motor pathways


How many subdivisions has the midbrain?



∙ Sensory – collection of fibers carry messages for specific senses;  

information sent to cortex via SNS

∙ Motor – nerve fibers that connect brain and SC to body’s muscles  

through SNS

∙ Autonomic NS (ANS) – sensory and motor pathways influence  

muscles that conduct involuntary movement such as heart and lungs

▪ Aristotle – non-material psyche gives human thoughts, perceptions, reasons ∙ Psyche is to concept of soul/spirit Don't forget about the age old question of What is the dynamic system theories?

▪ Descartes – dualism: behavior controlled by two independent systems, the  body and mind

∙ Body – material with spatial extent, so it responds  

mechanically/reflexively to events

∙ Mind – non-material without spatial extent, so mind decides what  If you want to learn more check out What are the physical properties of a mineral?

movements machine should make  

o Located in pineal body – in brainstem; based on logic that  

pineal body is the only structure in NS not composed of two  

bilaterally symmetrical halves

▪ Darwin – materialism: body and mind are one and the same; rational behavior  can be fully explained by workings of NS

o Insights from brain injury

▪ Broca – had patient who was paralyzed on right side of his body, lost his  speech, was only able to say “tan”; autopsy found lesion in third convolution  of left frontal lobeDon't forget about the age old question of Are psychological traits innate or do we acquire them?
If you want to learn more check out Who is tiberius sempronius gracchus?

2

∙ Demonstrated speech only located in one hemisphere; thus,  

discovering property of functional lateralization

∙ Known as Broca’s area – damage causes Broca’s aphasia which is  

the inability to produce coherent speech

∙ Associated with paralysis of right arm and leg; can’t articulate, but  

can understand meaning of words

▪ Wernicke – had patients who could speak, but speech was non-sensical; they  could also hear, but couldn’t understand/repeat what was said

∙ Autopsy found damage to superior portion of temporal lobe – known  

as Wernicke’s area, damage produces aphasia

∙ No opposite-side paralysis; can speak fluently, but what was said was  

confusing or made little sense; can hear, but can’t understand/repeat  

what was said

∙ Wernicke’s model – organization of language in brain:

o Sound sensations enter brain through auditory pathway; sound  

images stored in Wernicke’s area and are sent to Broca’s area  

for articulation over motor pathway

o Important for identifying disconnection syndromes; proposed  

that brain regions have different functions but still must  

interact to work correctly, identifying left hemisphere is  

dominant for language

∙ Neuron hypothesis – idea that unit of brain structure and function is nerve cell o Neurons: discrete self-directed cells, interact with each other, are not physically  connected

o Neurons send electrical signals that have a chemical basis

o Neurons use chemical signals to communicate

o Nervous system composed of two classes of cells:

▪ Neurons – produce behavior and mediate brain’s plasticity, allowing learning ∙ Every neuron has one axon; neurons can have many dendrites

∙ Dendrites and axons enlarge cell’s surface area to increase its  

interactions with other cells

▪ Glia cells – help neurons out, holding them together and providing support  functions such as delivering nutrients and removing waste

Chapter 3 

∙ Afferent – movement toward the brain

o Sensory pathways carrying messages from body toward brain and spinal cord ∙ Efferent – movement away from brain structure

o Motor pathways leading to body from brain and spinal cord to body

∙ CNS – consists of brain and spinal cord, both encased in bone

∙ PNS – encompasses everything else

o Somatic nervous system (SNS) – two sets of inputs and outputs to CNS; these are  spinal and cranial nerves to and from sensory organs and muscles, joints, and skin ∙ Spinal cord (SC) – lies under bony spinal column, a series of vertebrae categorized into:  cervical, thoracic, lumbar, sacral, and coccygeal

o Each body segment forms a ring, dermatome (skin cut), encircles spinal column o Each spinal segment connects SNS spinal nerve fibers to the same-numbered  dermatome, including organs and musculature that lie within it

▪ Cervical – control forelimbs, arms

3

▪ Thoracic – control trunk

▪ Lumbar – control hind limbs, legs

o Afferent fibers enter posterior SC to bring information in from body’s sensory  receptors; these spinal nerve fibers converge as they enter, forming a strand of fibers  referred to as posterior root

o Efferent fibers exit anterior SC to carry information from SC out to muscles, forming  anterior root

o SC capable of organizing complex actions, such as walking

o Reflexes – movements dependent only on spinal cord

▪ Specific movements elicited by specific sensory stimulation

▪ Examples – stimulation of pain/temperature receptors (flexion), stimulation of  fine touch (extension)

o Autonomic NS (ANS) – regulates internal organs and glands

▪ Sympathetic – arouses body for action, fight/flight

∙ Spinal nerves do not directly control target organs, rather SC is  

connected to chain of autonomic control centers, collections of neural  

cells called sympathetic ganglia

▪ Parasympathetic – calms the body down, rest/digest

∙ One part of parasympathetic system connects directly to SC –sacral  

region

∙ Greater part of parasympathetic system derives from three cranial  

nerves

o Vagus nerve – calms most of internal organs

o Facial nerve – controls salivation

o Oculomotor nerve – controls pupil dilation and eye  

movements

∙ Connects with parasympathetic ganglia near target organs

▪ Internal organs arranged segmentally in relation to SC; sensation not  

represented by SC

∙ Referred pain – pain in these organs is perceived from the outer parts  

of dermatome

∙ Brain stem – begins where SC enters skull and extends upward into lower forebrain  o Hindbrain – most distinctive structure is cerebellum, it protrudes above brainstem  core, its surface is gathered into folia (narrow folds)

▪ Evolved in size parallel with neocortex, four times more neurons than cortex  but are much more densely packed, coordinates motor learning and other  mental processes

▪ Damage to cerebellum – equilibrium problems and postural defects; also  impairs skilled motor activity

▪ Pons and medulla – serve many functions, including controlled  

waking/sleeping, and locomotion

o Midbrain – has two main subdivisions

▪ Tectum – “roof” of third ventricle, posterior sensory component

∙ Receives massive amount of sensory info from eyes and ears

∙ Its two sets of bilaterally symmetrical nuclei, superior/inferior  

colliculi, receive projections from retina of eye/ear, respectively

o Behaviors mediated by colliculi – locating objects in  

surrounding space and orienting to those objects

4

▪ Tegmentum – “floor” of third ventricle, anterior

∙ Nuclei related to motor functions

o Diencephalon – at midbrain and forebrain junction; houses hypothalamus,  epithalamus, and thalamus

▪ Hypothalamus – twenty-two small nuclei, motivated behavior: feeding, sex,  sleeping, movement

∙ Connects to pituitary gland to control endocrine system

▪ Thalamus – twenty nuclei that project to cerebral cortex

∙ All info cortex receives has been relayed through thalamus first

∙ Relays sensory info to appropriate targets – LBG, MBG, VLP

∙ Relays info between cortical areas

∙ Relays info between forebrain and brainstem regions

▪ Epithalamus – posterior part of diencephalon

∙ Pineal gland; secretes melatonin to influence daily body rhythms

∙ Regulates hunger and thirst – habenula

∙ Forebrain – cerebral cortex, basal ganglia and limbic system (subcortical structures) o Cortex envelopes both of these structures; these regions form circuits

o Basal Ganglia – anterior portion of cortex; ganglia form a circuit with the cortex ▪ Ganglia include – putamen, globus pallidus, and caudate nucleus

▪ Caudate nucleus – receives info from all cortex regions, sends info through  putamen and globus pallidus to thalamus, which then goes to frontal cortices ▪ BG have reciprocal connections with midbrain, specifically substantia nigra  of the tegmentum

▪ Associated with movement and learning (stimulus-response, habit learning) o Limbic System – self-regulatory behaviors (emotional memory, reward, navigation,  motivation)

▪ Amygdala – base of temporal lobe, emotion and species-typical behaviors ▪ Hippocampus – anterior medial of temporal lobe, personal memory and  spatial navigation

▪ Septum – emotion and species-typical behavior

▪ Cingulate cortex (cingulate gyrus) – above corpus callosum, sexual behavior,  social interactions

▪ Receives connections from olfactory structures

o Neocortex (cortex, outer part of forebrain)

▪ Expanded during evolutionary processes

▪ Comprises most of human brain (mammals)

▪ Six layers; two cerebral hemispheres separated by longitudinal fissures, four  lobes

∙ Projection map – map of location of inputs and outputs to cortex

o Each cortical lobe associated with specific sense/movement

o Primary areas:

▪ Frontal lobe – motor functions

▪ Parietal lobe – body senses

▪ Temporal lobe – auditory functions

▪ Occipital lobe – visual functions

o Secondary areas – adjacent to primary areas; elaborate info received from primary  area; interpret sensory input or organizing movements

5

o Tertiary areas (association cortex) – located between secondary areas, mediate  complex activities that are not sensory or motor, such as language, planning,  attention, memory

∙ Neocortex (cortex) is comprised of six layers

o Inner layers V and VI – send axons to other brain regions; are large, and specific to  motor cortex

o Layer IV – receives input from sensory systems and cortical areas

▪ Made up of densely packed cells in sensory areas

▪ Cortical areas in this layer are known as granular cortex

o Outer layers I, II, and III – receive input from IV, perform integrative function ▪ Well developed in secondary and tertiary cortex areas

∙ Brain has contralateral organization – each half responds to sensory info or controls muscle  movements from contralateral (opposite) side

▪ SNS transmits incoming sensory information to CNS, including vision,  hearing, pain, temperature, touch, and position/movement of body parts, and  produces movements in response

o Autonomic nervous system (ANS) – controls functioning of body’s internal organs to  rest and digest through parasympathetic (calming) nerves or to fight and flee through  sympathetic (arousing) nerves

∙ Brain and spinal cord are supported and protected from injury and infection in four ways: o Brain is enclosed in thick bone, the skull, and the spinal cord is encased in series of  interlocking bony vertebrae

▪ CNS lies within bony encasements, whereas PNS lies outside them, so  vulnerable to injury but can renew after injury by growing new axons and  dendrites

o Meninges – within body case enclosing CNS is a triple-layered set of membranes ▪ Dura mater – tough outer, double layer of tissue enclosing brain in a kind of  loose sack

▪ Arachnoid membrane – middle, very thin sheet of delicate tissue that follows  brain’s contours

▪ Pia mater – inner, moderately tough tissue that clings to brain’s surface o Brain and SC are cushioned from shock and sudden pressure changes by CSF, which  circulates through brain’s four ventricles, the spinal column, and within subarachnoid  space in brain’s meninges

▪ CSF continually produced and drained off into circulatory system through  connecting channels among ventricle

o Blood-brain barrier (BBB) protects brain and SC by limiting movement of chemicals  from rest of body into CNS and by protecting it from toxic substances and infection ▪ Astroglia stimulate cells of capillaries to form tight junctions with one  another, thus preventing many blood-borne substances from crossing from  capillaries into CNS tissues

∙ Information flows from dendrites to terminal buttons in a neuron; information conveyed  through electrical current that begins on dendrites, then impulse causes release of  neurotransmitters when it reaches terminal buttons

∙ Cell membrane – semipermeable, regulates material that enters/leaves cell; envelopes soma,  dendrites, axon, terminal buttons

o Separates extra/intracellular fluids, regulates movement of substances, regulates  concentration of salts, phospholipid bilayer

6

o Impermeable to intra/extracellular water – only nonpolar molecules can pass through  phospholipid bilayer

o Ions cannot freely enter cell because of polar surface; they’re repelled/blocked o Proteins act as gates to provide influx/efflux of substances

Chapter 4 

∙ Neuron’s electrical activity

o Concentration gradient – relative difference in amount of substance at different  locations

o Diffusion – motion causes molecules to spread out from high concentrated areas to  low concentrated areas

o Voltage gradient – difference in charge between regions that allows current flow ▪ Able to measure concentration of +/- charges across membrane

▪ Cations vs anions; ions move from high charge to low charge areas

o Resting potential – neurons at rest; cytoplasm has negative charge compared to  extracellular fluid (-70 mV, due to unequal distribution of charges)

▪ Produced by Na+, Cl-, K+, protein anions (A-)

▪ K+– normally inside axon, move out of cell (Na/K pump)

▪ Cl and Na+are normally outside of cell

o Graded potentials – sudden change in membrane voltage; localized, only occur when  axon is stimulated

o Hyperpolarization – occurs when negative current (increase in voltage) applied o Depolarization – occurs when positive current (decrease in voltage) applied o Action potential – brief change in polarity of membrane

▪ Triggered when membrane is depolarized – threshold potential

▪ Absolutely refractory period – occurs during depolarizing and repolarizing  phases of AP; axon membrane can’t trigger new AP

▪ Relatively refractory period – occurs during hyperpolarization phase of AP;  axon membrane only responds to stimulation that’s higher than that which  

initiated the first AP

∙ Nerve impulse – voltage change occurs at one point on membrane and brings adjacent points  to threshold potential

o AP is propagated down axon membrane; AP can’t travel backward because of  refractory period

∙ Large axon – quick AP transmission vs small axon – slow AP transmission ∙ Myelin sheath – insulation around axon created by Schwann cells (PNS) and  oligodendrocytes (CNS)

o Nodes of Ranvier – uninsulated regions between myelinated segments; voltage sensitive ion channels

o Saltatory conduction – AP jumping from one node to the next, which increase AP  transmission rate

∙ Excitatory postsynaptic potentials (EPSPs) – increase AP probability, open Na+channels ∙ Inhibitory postsynaptic potentials (IPSPs) – hyperpolarization, open Cl channels Chapter 5 

∙ Synthesis – DNA produces NT, which is imported into axon terminal; or NT is physically  produced in axon terminal because DNA send the building blocks there

o Synthesized NTs are stored in Golgi bodies and transported via microtubules to axon  terminal

7

o Since axon terminal contains mitochondria, NT can be physically created in axon  terminal – they simply use transporter proteins

∙ Release – NT sent to presynaptic membrane, which is then released because of action  potential (AP)

o Ca2+ channels, which are voltage-gated, are located on presynaptic membrane – release NTs when AP arrives

o Arrival of AP causes opening of Ca2+ channels, which then causes influx of Ca2+ into  axon terminal – the incoming Ca2+ will then bind to calmodulin (protein), which will  trigger NT release into synapse via exocytosis

∙ Receptor Action – NT moves through synapse, binding to receptors on incoming cell  membrane

o Once NTs have entered synapse, they will diffuse across synapse so that they may  bind to receptors (specialized proteins that are activated upon NT binding), which  will cause an excitatory or inhibitory effect in postsynaptic cell

o Excitatory – NT binding causes depolarization of postsynaptic membrane o Inhibitory – NT binding causes hyperpolarization of postsynaptic cell

o NT binding can cause modulatory effects in postsynaptic cell

o NT binding can cause generation of new synapse

o NT can also bind to autoreceptors – binding to autoreceptors means that NT is  binding to its own presynaptic membrane

▪ This type of binding will influence the cell that just released NT – thus,  

autoreceptors receive messages from own axon terminal

o Quantum – amount of NT by release of content from one synaptic vesicle ∙ Inactivation – NT can be taken back into presynaptic axon or can be broken down via  enzymes (if not inactivated, NT continues stimulation of nearby neuron)

o NT inactivated via diffusion, enzymatic degradation, reuptake, or by glia ∙ Central NS neurotransmission – modulatory roles in motor behavior, arousal, mood o The somas of small-molecule NTs lie within a certain region of brainstem, with  axons distributed in forebrain, brainstem, spinal cord

o Coordinate varying brain regions to act in concert

Chapter 6 

∙ Psychopharmacology – study of how drugs affect NS and behavior

o Drug effects depend on the varying routes of administration, quantity of drug, and the  circumstance at which the drug is taken

∙ Psychoactive drugs – substance that alters mood, behavior, thought; may manage  neuropsychological illness, promote craving, produce addiction

∙ Blood brain barrier (BBB) – permeable membrane that prevents substances from entering  brain; brain is very rich in capillaries, so if a substance were to pass through BBB, the  substance would be thoroughly absorbed

o Capillaries in brain composed of endothelial cells; capillaries are surrounded by  astrocytes, which maintain tight junctions

o Tight junctions form between the membranes of the endothelial cells – this allows a  one way entrance for substances

▪ Non-ionized/fat-soluble molecules (oxygen, carbon dioxide), can pass  

through capillary wall

▪ Large molecules (glucose, AA) are carried across capillary via active  

transport (protein pumps)

o Three areas of brain lack BBB (lack capillary cell wall)

8

▪ Pituitary gland (hypothalamus) – secretes hormones into blood

▪ Area postrema (brain stem) – toxic substances trigger vomiting

▪ Pineal gland – allows hormone entry (control day/night cycles)

∙ Tolerance – decline in drug response due to repeated drug use

o Experiment done with prisoners

▪ Prisoners were kept in an intoxicated state every day for a thirteen-week  period; however, prisoners did not remain intoxicated every for the entire  duration

▪ First few days – prisoners had rising blood alcohol levels and had the  associated behavior signs of intoxication

▪ Day 12 to 20 – blood alcohol level and associated behaviors declined  regardless of constant alcohol intake

o Metabolic tolerance – increase in enzymes that degrade alcohol in liver, brain, blood;  body metabolizes alcohol quickly, blood alcohol levels decrease rapidly

o Cellular tolerance – neurons modify activities to minimize alcohol effects in blood;  explains decrease in associated behaviors despite high blood alcohol levels o Learned tolerance – contributes to decreased in associated behaviors; learn to behave  with everyday problems while intoxicated

∙ Sensitization – increased response to equal doses of drug, occurs with occasional use  (opposite of tolerance)

o Produces structural changes in brain; long-lasting

∙ Antianxiety agents and sedative hypnotics (anxiolytics)

o Low doses of these drugs reduces anxiety, medium doses induce sedation, high doses  induce coma, extremely high doses are fatal

o Antianxiety agents – benzodiazepines (valium, Xanax), stress, sleep aid o Sedative hypnotics – alcohol, barbiturates (sometimes used for sleep aid, anesthesia);  both induce sleep, coma (high doses)

▪ Produces tolerance and cross-tolerance, which occurs when tolerance has  built up for one drug and is carried over to another drug of the same class ▪ Influences GABAA receptor – excitatory effect triggers Cl ion influx, which  causes hyperpolarization

∙ When hyperpolarization occurs, the cell will not fire another AP

∙ This hyperpolarization effect is inhibitory – it decrease the neuron’s  

firing rate

o Barbiturates vs. benzodiazepines at GABA receptor

▪ Barbiturates increase GABA binding to cause hyperpolarization

∙ High dose, high inhibitory effect

▪ Benzodiazepines enhance GABA function by increasing ion channel opening  frequency – if GABA not present in system, the benzodiazepines will not  work

∙ Antipsychotic agents

o Psychosis – behavioral disorders that cause hallucinations, delusions (schizophrenia) ▪ First generation antipsychotics (FGAs) – phenothiazine, butyrophenone ∙ Block dopamine (D2) receptors; many side effects associated with  

drug intake – weight gain, motor impairment

▪ Second generation antipsychotics (SGAs) – clozapine, risperidone

∙ Block dopamine (D2) receptors and serotonin (5-HT2) receptors;  

fewer side effects, SGAs don’t control symptoms as well as FGAs

9

∙ Antidepressants and mood stabilizers

o Major depression – mood disorder, feelings of guilt, worthlessness; disruptive eating  habits, sleep disturbances, suicidal thoughts

o Antidepressants – improve chemical neurotransmission at 5-HT, NE, Histamine, and  ACh synapses (maybe DA); work quickly, but antidepressant actions take weeks to  develop

▪ Monoamine oxidase inhibitors (MAOIs)

▪ Tricyclic antidepressants

▪ Selective-serotonin reuptake inhibitors (SSRIs)

o Mood stabilizers – used in treatment of bipolar disorder

▪ Bipolar disorder – depression period followed by normal periods, then  periods of mania

▪ Salt lithium carbonate, valproate – alter sodium ion pump behavior, which  aids in manic episodes

▪ Antipsychotic drugs that block dopamine receptors can control hallucinations  associated with mania

∙ Opioid analgesics  

o Opioid – drug that binds to receptors that are sensitive to morphine

▪ Derive from opium; codeine is converted into morphine by liver

▪ Morphine, codeine, heroin, hydromorphone, methadone, oxycodone

o Endorphins/endomorphins – peptides in body that have opioid-like effects ▪ Have their own receptors – mu, kappa, delta

o Tolerance developed very quickly

∙ Psychotropic – stimulants that affect mental/motor activity, arousal, mood, perception o Behavioral stimulants – increase motor behavior, can boost alertness; addictive ▪ Cocaine – blocks DA reuptake

▪ Amphetamine – stimulates DA release, but blocks DA reuptake so synapse  overfills with DA

∙ Alertness, weight loss; ADD, ADHD (example: Adderall)

o General stimulants – increase cell’s metabolic activity

▪ Caffeine prevents cAMP breakdown, which increase glucose production – more glucose production enables cell to make more energy, causing more  cellular activity

∙ Psychedelics and hallucinogens

o Alter cognitive processes, sensory perception; produce hallucinations

o ACh psychedelics (scopolamine) – can block or improve ACh neurotransmission at  cholinergic synapses

o Anandamide psychedelics – anandamide in general prevents memory formation of  everything that occurs throughout the day, it prevents memory overload

▪ THC activates CB1 and CB2 receptors of anandamide, causing impaired  memory

▪ Used for – nausea/vomiting relief, appetite inducer, chronic pain, glaucoma,  MS, slow onset of disease for Alzheimer’s and Huntington’s, epilepsy

o Serotonin psychedelics – LSD, MDMA, ecstasy, and psilocybin (mushrooms) stimulate serotonin receptors and serotonin autoreceptors to prevent activity of other  serotonergic neurons

∙ Substance abuse – repetitive drug use

∙ Substance dependence – extreme form of substance abuse, known as addiction

10

o Physical dependence on drug, as well as desire to abuse it

o Need higher dose to achieve desired effect

o Undergo withdrawal symptoms if drug use suddenly stops

∙ Hypothesis – drugs that are abused tend to act on dopamine receptors

o Animals can be easily trained to press a lever that will stimulate DA receptors o Abused drugs will release DA or prevent DA reuptake, which will prolong  dopamine’s availability

o DA antagonists are not abused

∙ Dependence hypothesis – withdrawal symptoms (physical and psychological) experienced  once drug is not taken

∙ Hedonic hypothesis – drug purposely used to experience pleasure

∙ Incentive-sensitization theory – addiction acquired unconsciously; people don’t start a drug  hoping to become addicted to it

o Addiction is a result of conditioned learning – if I take this drug, I receive a reward of  pleasure, which leads to repetitive use

▪ Once behavior has been learned because of classical conditioning, the user  will begin to engage in drug-seeking behavior

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