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Textbook Notes - Week 8.docx

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Ashley Waggoner Denton

PSY 100 Textbook Notes – Week 8 Sleeping: pp. 155 – 165 Thinking: pp. 341 – 365 Learning: pp. 243 – 284 WHAT IS SLEEP?  Many brain regions are more active during sleep than during wakefulness  When people are awake, their brains’ neurons are extremely active, as evidence by short, frequent, desynchronized brain signals known as beta waves  When people are sleeping, brain activity slows and becomes more synchronized, a pattern that produces alpha waves STAGES OF SLEEP: 1. As you drift off to sleep, you enter stage 1, and begin to experience theta waves, from which you can be aroused easily a. If awoken, you will probably deny you were sleeping b. You might see fantastical images or geometric shapes; might have a sensation that you’re falling or that you limbs are jerking 2. Stage 2, your breathing becomes more regular, and you become less sensitive to external stimulation. You are now really asleep a. EEG would display theta waves, although interspersed with occasional bursts of activity called sleep spindles and large waves called k-complexes. b. Some researchers believe this signals are from brain mechanisms involved with shutting out the external world and keeping people asleep 3. Stage 3 is a deeper sleep, marked by large, regular brain patterns called delta waves a. Often referred to as slow-wave sleep b. Very hard to be awoken from this sleep 4. Stage 4 is very similar to stage 3 REM SLEEP:  After about 90 minutes of sleep, the cycle reverses, returning to stage 3, and then to stage 2  The EEG suddenly shows a flurry of beta wave activity that usually indicates an awake, alert mind  Eyes dart back and forth rapidly beneath closed eyelids, giving this stage the name rapid eye movement sleep o Sometimes called paradoxical sleep o Regions in the occipital cortex and brain stem regions are more active during REM than during waking hours  Accompanied by genital arousal in both sexes at all ages  80% of the time when awoken from REM sleep, the sleeper reports being dreaming, compared with less than half of the time in other sleep stages  Over the course of the night, the cycle repeats PSY 100 o As morning approaches, the cycle becomes shorter and the sleeper spends more time in REM sleep, and doesn’t get down into the deepest sleep stages SLEEP DISORDERS:  Insomnia: a disorder characterized by an inability to sleep  Those who were most anxious or depressed are most likely to develop insomnia  Pseudoinsomnia: basically dream all night that you’re not sleeping  Sleep Apnea: A disorder in which a person stops breathing while asleep o Most common in obese middle-aged men  Narcolepsy: A sleep disorder in which people fall asleep during normal waking hours  REM Behaviour Disorder: Normal paralysis that accompanies REM sleep is disabled so that people act out their dreams while sleeping  Somnambulism: Sleepwalking, occurs during stage 4 sleep RESTORATION AND SLEEP DEPRIVATION:  Restorative Theory: Sleep allows the brain and body to rest and to repair themselves o Growth hormone is released during sleep  Sleep deprived people show increased activation of the prefrontal cortex, suggesting it may be overcompensating for sleep deprivation’s effects  Sleep deprivation causes mood problems and decreases cognitive performance  Microsleeps: Brief, unintended sleep episodes, ranging from a few seconds to a minute, caused by chronic sleep deprivation  Depriving depressed people of sleep sometimes alleviates their depression o Sleep deprivation leads to increased activation of serotonin receptors, as do drugs that treat depression CIRCADIAN RHYTHMS  Circadian Rhythms: The regulation of biological cycles into regular patterns  Circadian Rhythm Theory: Sleep has evolved to keep animals quiet and inactive during times of the day when there is greatest danger, usually when its dark o An animal’s typical amount of sleep depends on how much time that animal needs to obtain food, how easily it can hide, and how vulnerable it is to attack FACILITATION OF LEARNING:  Sleep is involved in the strengthening of neural connections that serve as the basis of learning  Circuits wired together during the waking hours are consolidated during sleep  Infants who learn an incredible amount in a few years, sleep the most and also spend the most time in REM sleep PSY 100  Many neural mechanisms are involved in producing and maintaining circadian rhythms and sleep  The pineal gland secretes melatonin o Bright light suppresses the production of melatonin o Darkness triggers the release of melatonin  SLEEPLESS gene regulates a protein that reduces action potentials in the brain, loss of this protein leads to an 80% reduction in sleep BRAIN STEM AND AROUSAL:  Stimulating the reticular formation in the brain stem leads to increased arousal in the cerebral cortex, if you sever the fibres from the RF to the cortex, animals fall asleep and stay asleep until they die o Low levels of RF activity produce sleep, high levels lead to awakening  Basal forebrain, a small area just in front of the hypothalamus, is involved in inducing non-REM sleep o Lesion in this area leads to insomnia o Once activated, the region sends inhibitory signals to the RF, thereby reducing arousal and triggering sleep People Dream While Sleeping  Dreams: the product of an altered state of consciousness in which images and fantasies are confused with reality  Dreams occur in REM sleep and non-REM sleep o Dreams in REM sleep are more likely to be bizarre, involving intense emotions, visual and auditory hallucinations, illogical contents, and an uncritical acceptance of events o Non-REM dreams are often very dull, about mundane activities such as deciding what clothes to wear  REM dreams contents result from activation of brain structures associated with motivation, emotion, and reward along with activation of visual association areas o The brains emotions centres and visual association areas interact without self- awareness, reflective thought, or conscious input from the external world WHAT DO DREAMS MEANS?  Manifest content: The plot of a dream; the way a dream is remembered  Latent content: What a dream symbolizes, or the material it is disguised in a dream to protect the dreamer ACTIVATION-SYNTHESIS HYPOTHESIS  Activation-Synthesis Hypothesis: A theory of dreaming that proposes that neural stimulation from the pons activates mechanisms that normally interpret visual input  Sleeping mind tries to make sense of activity in visual and motor neurons by synthesizing it with memories  Epiphenomenal – the side effect of mental processes PSY 100  Amygdala the source of dreams’ emotional content, and the deactivation of the frontal cortices contributes to dreams’ delusional and illogical aspects  Concerned more with REM dreams than non-REM EVOLVED THREAT-REHEARSAL STRATEGIES  Antti Revonsuo proposed an evolutionary account wherein dreams sometimes simulate threatening events to allow people to rehearse coping strategies  Dreams help humans survive by providing solutions to adaptive problems Thinking: pp. 341 – 365  We use two basic types of representations: o Analogical Representation: A mental representation that has some of the physical characteristics of an object; it is analogous to the object  Maps, for example, correspond to geographical layouts o Symbolic representation: An abstract mental representation that does not correspond to the physical features of an object or idea  The word “violin” stands for a musical instrument, there are no correspondences between what a violin looks or sounds likes and letters or sounds that make up the word violin  When you recall a picture you saw, your brain processes mimic the activity that occurred when you first saw the picture  We can represent only a limited range of knowledge analogically  Categorization: Grouping objects into categories according to the objects’ shared properties  Concept: A mental representation that groups or categorizes objects, events, or relations around common themes  Defining Attribute Model: The idea that a concept is characterized by a list of features that are necessary to determine if an object is a member of the category o Suggests that all of a given category’s attributes are equally salient in terms of defining that category o Boundaries between categories are fuzzier than this model suggests o Posits, perhaps inaccurately, that all members of a category equally represent that category  Prototype Theory: an approach to object categorization that is based on the premise that within each category, some members are more representative than others  Exemplar Model: Information stored
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