Chapters 8 and 10
Chapters 8 and 10 PSYCH 50
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This 8 page Class Notes was uploaded by Emily Wu on Wednesday February 24, 2016. The Class Notes belongs to PSYCH 50 at Stanford University taught by Justin Gardner in Winter 2016. Since its upload, it has received 22 views. For similar materials see Intro to Cognitive Neuroscience in Psychlogy at Stanford University.
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Date Created: 02/24/16
Chapter 8: Memory: Varieties and Mechanisms Introductory Box ● H.M.: suffered from epilepsy, surgeons removed much of both temporal lobes and hippocampi → relieved seizures, but had memory deficits ● no difficulty in other cognitive domains: no IQ deficits, sensory and perception remained, frontal lobe/executive tasks remained ● could not remember events after surgery ● memory deficits occurred in all sensory modalities ● working memory intact, but remembering new events/facts impaired ● memory deficits limited to events/facts, not performance ● mirror drawing tas reproduce figures from mirror onto a piece of paper ○ HM would get better at task over time, but wouldn’t remember that he did the task before Memory Phases, Processes, Systems, and Tasks ● encoding:changes in strength/number of synaptic connections due to an experience ● storageretention of memory traces over time ● retrievaaccessing stored memories traces ● working memory: maintains and manipulates information for a short duration ● declarative memoryconscious memory ○ can be episodic (events) or semantic (facts) ● nondeclarative memory expressed through performance independent of consciousness ○ priming, skill learning, and conditioning Dissociating Memory Systems Working memory vs. declarative memory ● anterograde amnesia: can’t remember events occurring after the brain damage ● retrograde amnesia can’t remember events occurring before the brain damage ● amnesia usually occurs through bilateral damage to medial temporal lobes ● generally affects declarative memory rather than working memory or nondeclarative memory Nondeclarative Memory ● priming previous encounter of a related/same stimulus changes the processing of a stimulus later ○ ex: seeing words like “pillow” and “sleep” beforehand will make you read B_D as “bed” ● skill learni gradual improvement in performance due to repeated practice ● conditioninresponses to associations between stimuli Priming ● direct primin the prime and target stimuli are the same ○ perceptual: test cue and target perceptually related (e.g., B_D → BED) ○ conceptual: test cue and target semantically/associatively related (e.g., pillow → bed) ● indirect primiprime and target stimuli are different ● repeated suppressionneurons show less firing activity when subject is shown same stimulus repeatedly ● repeated suppression of neural activity(neural priming) leads to enhanced processing of a stimulus (behavioral priming) Skill Learning 1. motor skill learning: improvement of motor skills, e.g., playing instrument or sport 2. perceptual skill learning: improvement in processing repeated identical/similar stimuli 3. cognitive skill learning: improvement in problemsolving tasks ● weather prediction task: used to test cognitive skill learning ○ subjects look at four cards with shapes associated with future weather conditions, then predict whether weather will be rain or shine ○ each card is only probabilistically related to weather outcome → difficult to infer explicit rule ○ subjects must use cognitive abilities to find which cards will produce a certain outcome → over many trials, accuracy will improve ○ patients with amnesia learned more slowly, but eventually made about the same amount of correct predictions as control subjects ○ patients with parkinson’s (damage to basal ganglia) had trouble with task ● pairedassociation task: subjects learn that certain pairings of cards denote that the weather will be rain or shine ○ medial temporal lobe showed more activity in this task ○ basal ganglia showed more activity in weather prediction task ● interpretation: skill learning depends on integrity of basal ganglia Conditioning ● classical conditioning: ○ unconditioned response (UCR): an innate response to a stimulus ○ unconditioned stimulus (UCS): the stimulus that elicits the UCR ○ conditioned stimulus (CS): an unrelated stimulus paired with the UCS ○ conditioned response (CR): the reflex that happens with presentation of the CS ○ ex: dog salivates (UCR) at sight of food (UCS) → pair bell tone with food → dog salivates (CR) when it hears the bell tone (CS) ● operant conditioning increasing or decreasing a behavior by rewards or punishments ● acquisition establishment of the conditioning ● extinctio: removal of unconditioned stimulus when subject repeatedly performs conditioned response → conditioned response decreases in absence of unconditioned stimulus Cellular Mechanisms of Memory ● memory traces: physical and biochemical changes of memory storage in the brain ○ memory traces for visual info generally stored in visual cortices, auditory info in auditory cortices, etc. ○ consist of networks of neurons ● Hebbian learning: neurons that functioned independently before become linked when associating objects, actions, or concepts ○ through experience, connections between neurons are strengthened as they fire action potentials at the same time ● habituation reduced response when same stimulus is repeated ○ involves decrease in neurotransmitter release at synapses between motor and sensory neurons ● sensitizatio increased response to habituated stimulus when paired with an averise stimulus ○ increased neurotransmitter release ● long term potentiation (LTP): ○ looking at two pathways in hippocampus, both can be stimulated independently ○ researchers record the postsynaptic potentials that receive input from each pathway ○ when pathway 1 is stimulated by a high frequency, postsynaptic potentials are enhanced ○ postsynaptic potentials are enhanced only by input from pathway 1, not pathway 2 ○ effect lasts for minutes or hours ● LTP: ○ could explain how single experience forms a memory LTP can be induced by single highfrequency stimulation ○ could explain how memories lasts for days and weeks since LTP lasts a long time ○ LTP has specificity that explains specificity of memories only synapses activated during stimulation are enhanced ● long term depression (LPD): ounterbalances LTP ○ elicited by lowfrequency stimulation over longer period ○ also specific to activated synapses ● dendritic spines protrusions from dendritic branches that receive excitatory input from other neurons → morphs/changes during memory encoding ○ diameter and length of spine may change ○ other spines may emerge from spine or disappear ○ could support memory retention or loss by increasing/decreasing synaptic strength Chapter 10: Emotion What is Emotion? ● emotion: conscious feelings ○ conceptualized as composite of feelings, expressive behavior, and physiological changes Psychological Classification of Emotions Categorical theories ● each emotion is a discrete, independent entity ● basic emotions:innate, pancultural, evolutionary, shared across species (e.g., anger, sadness, happiness, fear, disgust, surprise) ● complex emotions: shaped by culture and society, expressed by a combination of basic emotions Dimensional theories ● each emotion is a point within two or more continuous dimensions ● two major dimensions are arousal and valence ○ arousal: physiological and subjective intensity of emotion ○ valence: relative pleasantness of emotion Component process theories ● emotions are fluid which have flexible interactions with multiple component processes ● emotions arise from combinations of specific appraisals from a situation Early Neurobiological Theories of Emotion ● generally, emotion broken down into 3 processing stages: ○ evaluation of sensory input ○ conscious experience of feeling ○ expression of behavioral and physiological responses JamesLange feedback theory ● experience of emotion depends on brain’s recognition of bodily response ● emotional stimulus → bodily response → recognition of behavior in cerebral cortex → feeling CannonBard diencephalic theory ● argued that a bodily response does not uniquely determine a feeling (e.g., flushing of skin can indicate anger or embarrassment) ● emotions and bodily reactions are processed simultaneously by diencephalon (hypothalamus and thalamus) ● emotional stimulus → diencephalon and cerebral cortex → bodily response and feeling Papez circuit and KluverBucy syndrome ● KluverBucy syndrome: damage to temporal lobes results in loss of fear, visual agnosia, hyperorality, altered food preferences, hypersexuality, inability to evaluate emotional significance of objects evident when frontal lobe is disconnected from amygdala ● Papez circuit:in medial walls of forebrain that contributed to emotion include thalamus, hypothalamus, hippocampus, cingulate gyrus Limbic system theory ● amygdala, hippocampus, orbitofrontal cortex, cingulate gyrus system that contributes to emotion ● hippocampus thought to be the integrator of emotions ● criticisms: limbic brain areas don’t have as much structural coherence such as the sensorimotor systems, damage to hippocampus shows deficits in memory but not as much on emotion Contemporary approaches to Studying the Neurobiology of Emotion Fear acquisition ● use of classical conditioning to have subjects associate fear to a stimulus, then observe the change in behavior and physiology ● amygdala responsible for acquisition and expression of conditioned fear ● skin conductance responses (SCR): electrodes placed on skin surface to measure electrical activity in response to emotions ○ sweat glands activated more during emotional arousal, increased electrical conductance ● patients with damaged amygdala have smaller startle response and lower SCRs Somatic marker hypothesis ● reactivation of somatosensory patterns for a given emotion/event being recalled calls up relevant somatic markers (autonomic, endocrine, and musculoskeletal changes) and helps one make behavioral changes based on this information → leads to decision making based on past experiences Interactions with Other Cognitive Functions Emotional influences on memory consolidation ● memory modulation hypothesis: emotionally arousing events enhance memory ○ amygdala plays key role in consolidating/storing memories after emotional episodes ● stress hormones such as epinephrine, norepinephrine, and cortisol are secreted when sympathetic nervous system is stimulated ● these hormones activate receptors in the central nervous system → effects are slower than neural signaling, more effective during memory consolidation Regulation of Emotion ● emotion regulation: how people attempt to influence the intensity/duration of emotions they feel ● model: people change emotional response by regulating timing of engagement (before/after emotional response is elicited) and regulatory target (controlling physiological expression or cognitive interpretation of emotion) ● situation selectio changing behavior patterns before emotion is elicited to avoid expressing emotion altogether ○ ex: person with fear of flying chooses to ride train ● cognitive reappraisal interpret meaning of elicitor in a way that changes its emotional impact Box 10A ● psychophysiology: relates emotion to changes in body ● viscera: body’s internal organs ● autonomic nervous system: regulates viscera, responsible for digestion, respiration, reproduction has two subcategories ○ sympathetic division: deals with fightorflight functions (e.g., increased heart rate, increased perspiration, faster breathing), arousal of body ○ parasympathetic division: counters the effects of sympathetic division ● enteric nervous system: innervates the gut, regulate locally ● activity of these nervous systems can be measured by: ○ skin conductance response: electrical conductance of skin’s surface → higher arousal (e.g., fear or surprise) leads to more perspiration and higher conductance ○ startle response: reflex to a startling stimulus, measured by eyeblink reflex
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