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145 Cards in this Set
- Front
- Back
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How does learning change? |
-# of neurons -size of graded potentials (opens flood gate of info) -# of dendrites (post synaptic receptors) |
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Where are memories stored? |
Patient HM ensued resurgence of memory research in 1950s Hippocampus |
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Founders of Modern Psychology (MEMORY RESEARCH) |
Herman Ebbinghaus William James |
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Theodore Ribolt |
1st clinician who called the nature in time course of amnesia that accompanies dementia Dementia is any vague form of cognitive impairment of thinking, can involve impairment in recalling memory
1) loss of memory of most recent experienced events -things done an hour or day ago, relative preservation of remote events -where u grew up, family members |
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Ribolt’s Law |
TIME GRADIENT commonly observed retrograde amnesia where recently occurring events are the first to go, relatively older events are preserved |
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Sergei Korsakoff |
Described a series of alcoholic patients whom were vitamin deficient as most of their caloric intake came from alcohol
Had amnesia for recent and very new material, most recent events seem to be first again, patients repeat themselves in conversation and would not recognize Sergei from one day to another but had remarkable memory of past events |
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Carle Wernicke |
Described an acute clinical syndrome involving gait ataxia (inability to move), opthalmoparesis, and confusion that sometimes is combed into chronic amnesia -Wernicke looked at what was different in the brain notes difference in pathology of 3rd ventricle (slightly larger located at bottom of brain) -Mammillary bodies and dorsal medial thalamus shrunken and misshapen= enlargement of ventricles thru which fluid flows
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Wernicke’s Area |
Comprehension of speech |
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Broca’s Area |
Production of speech |
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ARNOLD PICK |
-interested in individuals who suffered in degeneration of episodic memory; couldn't remember episodes of events in their lives -back of brain= typical construction of gyri & sulci yet gyri are huge and sulci are tiny -selective loss of brain matter in frontal lobe of brain |
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VLADIMIR BEKHTEREV |
-individuals suffering from amnesia: softening of medial temporal lobes -differs from areas around it; includes hippocampus -hinted that hippocampus (although he did not name it at the time) played a role in memory |
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WILLIAM SCOVILLE |
1954- reported on profound memory loss of 2 patients which underwent trephining with an ablation (scarring/ destroying) of part of their brains -whole drilled in patients, lifted a part of frontal lobe, and scratched out a part of their brains -in some patients that experience severe epileptic episodes this may be the only solution (destroy site of brain that is starting the seizures- medial temporal lobes) -selectively and successfully eliminated seizures yet they were left with profound memory loss -anterograde amnesia- they no longer remembered things which were happening to them, presenting them with facts will cause them to not remember what they were just told, but they can remember preserved memory from a long time ago (described by older psychologists) |
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HENRY MOLAISON (HM) |
-Patient of William Scoville -Profound memory loss but all aspects of personality were relatively intact -very nice, single person to make the biggest contribution to psychology
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SURGICAL PROCEDURE PERFORMED ON HM |
-bilateral resection of the rostral MTLs --> hippocampal formation -->amygdala -->overlying cortex |
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Hippocampus involved in... |
-the formation of many memories -regeneration of neurons |
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DENTATE GYRUS |
Main gyrus in hippocampus, where regeneration of neurons occurs -associated with hippocampal sulcus |
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MTL LOBES IN NORMAL INDIVIDUAL vs HM (after surgery) |
Hippocampus and all tissue surrounding it (parahippocampal gyrus +entorhinal area) damaged in HM |
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HM was able to learn and remember what after his surgery? |
*Skills like mazes & puzzles* |
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BRENDA MILLNER |
-studied HM heavily -described HM as having a series of severe memory benefits -HM was capable of forming lots of different memories despite the fact that he did not have a hippocampus -Memory is not a distinct construct but can be divided into categories -Middle of the hippocampus stores specific memories |
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DIGIT SPAN |
H.M. can repeat digits, provided that the time between learning and recall is within the duration of short term memory -requires focus and no multitasking -shorter and relied on attention *PROVES HM'S SHORT TERM MEMORY W/O HIPPOCAMPUS* |
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BLOCK-TAPPING MEMORY-SPAN TEST |
Test demonstrated that H.M. amnesia was GLOBAL- not limited to one sensory modality -shorter and relied on attention *PROVES HM'S SHORT TERM MEMORY W/O HIPPOCAMPUS* |
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MIRROR-TRACING TASK |
-HM given a shape (ex: star) so that he could only look at it through a mirror and trace it out -demonstrated learning through being effective and quick in a task (# of times he intersected with a line) but if you give him -lots of errors on first day, but if you give him 10 spaced out trials within the same day, he will get better on the first day -on the second day, he will not remember doing it, but behaviorally he acts in a way that demonstrates that he does know what he's doing -quickly improves performance on that same day -3rd day: developed a high level of proficiency, remembers things behaviorally without demonstrating awareness |
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IMPLICIT/PROCEDURAL MEMORIES |
-not recalled but demonstrated through remembering how to do something (based on actions) |
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MIRROR-READING TASK (REVERSED TEXT) |
-if you practice reading text backwards then you get better and better and doing so, HM was good at this |
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INCOMPLETE MEMORY TEST |
-HM asked what we are looking at, likely to make mistakes -more details with each set- you can tell it is an airplane -HM does accurate job by set 4, when asked to perform the same task with the same stimuli then he makes fewer errors, less so then when he had more information on a previous day, he does not know where it comes from but he has an intuition or familiarity with what is being presented to him *tests whether you can fill in the voids to accurately identify an object* |
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3 MAJOR SCIENTIFIC CONTRIBUTIONS OF HMs CASE |
1) Identified that the MTLs were not relevant to some memories -->they form explicit memories, but are not where they are stored as HM remembered previous events like his vacation & childhood facts 2) STM, remote memory, and LTM are distinctly separate processes in the brain which occur in different places in the brain 3) Memory may exist (implicit) but not be able to be recalled (explicit) |
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What is the role of the hippocampus?? |
*DOES NOT STORE MEMORIES* *TRANSFERS SHORT TERM MEMORIES TO LONG TERM* -->so long as you are paying attention |
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EXPLICIT MEMORY |
Memory exists & can be consciously recalled |
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IMPLICIT MEMORY |
Experiental/Functional form of memory that cannot be recalled |
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2 CATEGORIES OF LONG TERM MEMORY |
1) DECLARATIVE Things you know that you can tell others 2) NONDECLARATIVE (PROCEDURAL) Things you know that you can show by doing |
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It is harder to understand the level of declarative memory within ________ ________ |
ANIMAL MODELS --> they do not have the aspect of language to convey their understanding --> they can show you something by doing but that is nondeclarative *hard to differentiate between declarative & nondeclarative memories in animal models* |
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DELAYED NON-MATCHING-TO-SAMPLE TASK |
*DELAYED NON-MATCHING-TO SAMPLE TASK= A TEST OF OBJECT RECOGNITION MEMORY THAT REQUIRES MONKEYS TO DECLARE WHAT THEY REMEMBER* -Primate is rewarded by picking up an element in their environment underneath which is a delicious food -Formation of a memory from one instance to next -Follow up with later test to see if an animal will remember -If they are rewarded with picking up the same thing they remember, we cannot be sure it is a declarative memory --> could be implicit familiarity (due to seeing it before), could be a guess --> in this task they train the primate to select an item they have never seen before --> they must look at the objects in front of them, declare a familiarity, knowing to reach for the opposite item, this is what they reasoned to be an internal declaration |
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DELAYED NON-MATCHING-TO-SAMPLE TASK ON PRIMATE WHO WAS ABLATED of HIPPOCAMPUS, AMYGDALA, RHINAL CORTEX (same as HM) |
-Performance good on control circumstances before any changes are made to a primate's brain -Lesion of hippocampus= lower performance -Lesion of hippocampus + entorhinal cortex +parahippocampal cortices= even lower performance -Lesion extended to include anterior entorhinal + perifrontal cortices -->consolidation involves hippocampus as well as other parts of the MTLs |
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STEPS OF DELAYED NON-MATCHING-TO-SAMPLE TASK |
1) Monkey moves to sample object to obtain food from beneath it 2) Screen lowered in front of monkey during delay period 3) Monkey confronted with sample object & unfamiliar object 4) Monkey must remember sample object & then select unfamiliar object |
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The severe disruption of new declarative memories is due to both.... |
.....the hippocampus & nearby areas |
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PATIENT N.A. |
-4-5yr old boy -playing with an old toy soldier with a long sword which he jammed up his nose, punctured cribriform plate (bony structure separating olfactory neurons from olfactory bulb- most easily damageable structure of brain) -damage to mamillary bodies of ventral side of brain all the way up to dorsal medial thalamus --> caused short term and long term memory deficits due to damage to dorsomedial thalamus & mamillary bodies --> Like H.M., he has STM but cannot form declarative LTM |
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Memory deficits need not be restricted to the... |
...HIPPOCAMPUS |
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KORSAKOFF'S SYNDROME |
Memory deficiency caused by lack of thiamine -Seen in chronic alcoholism -Damage to mamillary bodies (in limbic system) & dorsomedial thalamus basal frontal lobes but not hippocampus --> both parts are smaller -->deficiency causes temporary dysfunction of parts of limbic system |
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STM-->LTM CONSOLIDATION |
-AMYGDALA -ENTORHINAL CORTEX -MAMILLARY BODIES -DORSAL MEDIAL THALAMUS -HIPPOCAMPUS |
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PATIENT K.C. |
-motorcycle accident -could retrieve memories about facts & details (declarative memory) but could not recall personal memories (episodic memories) -widespread brain damage including bilateral hippocampal lesions= memory impairment --> damage to MTLs + right frontal cortex (damage more extensive on right side) -KC can learn new semantic knowledge without episodic memory |
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How do we determine if the right side of the brain is therefore responsible for episodic memory storage? |
Ask participants to tell a story they previously read (recall) vs telling a story of their own lives which they have experienced (episodic) 1) YOUR STORY -temporal lobe activation in right and left hemispheres -greater activation in frontal lobes -favouring of right hemisphere of brain 2) THEIR STORY -temporal lobe activation in right and left hemispheres -->PERSONAL MEMORIES ACTIVATE A DISTINCT REGION OF YOUR BRAIN FROM OTHER KINDS OF EPISODIC MEMORY (in distinct places in cortex) |
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ALZHEIMER'S DISEASE |
-Selectively destructs ACh neurons in frontal cortex + MTLs which are evenly distributed across all areas -behavioral deficits: accompanied with a form of anterograde amnesia (relative preservation of oldest events, can recall older events in life but not recent) |
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AMYLOID PLAQUES |
*Alzheimer's* -Where tangles + plaques are localized is where Alzheimer's occurs -Targets areas associated with memory formation (frontal cortex + MTL) |
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Patients with Alzheimer's disease gradually lose may neurons in the ______ ________ that make the neurotransmitter __________ |
BASAL FOREBRAIN neurons make ACETYLCHOLINE |
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SPATIAL LOCATION RECOGNITION MEMORY TASK |
-Rat learns that one of the arms of an octagonal structure is associated with a food reward every time they go down it, form a spatial memory of where food is located -Ablation different areas of brain to see how behavior is affected -Generally well with short delay (75%) and a little less better with more delay --> we are forming a STM Damaging visual area makes them better which is weird Damaging hippocampus= dramatic performance drop --> suggests hippocampus consolidates memories and makes inputs to memories like where things are located |
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HIPPOCAMPUS + SPATIAL MEMORY |
-Hippocampus is a lot larger in food-storing birds that cache their food in order to find it later to survive winter than non-food-storing birds -->ENCODING OF PLACE OCCURS IN HIPPOCAMPUS |
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HIPPOCAMPUS + PLACE CELLS |
-Hippocampus is important in spatial learning -Scientists record DENTATE GYRUS activity -rats asked to move through a maze -place cells of hippocampus are exclusively active when in certain parts of the maze -->place cells become active when in or moving towards a particular location -->Hippocampus specializes in knowing where things are |
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LONDON TAXICAB EXPERIMENT |
-Explored how individuals in complex environments did so with relative ease -Taxicabs were asked how to get from one place to another by relaying all the directions they might take while in a fMRI scan -Compared to other individuals who do not have to navigate so extensively --> SUBTRACTIVE METHOD: looking at difference in activity; all activation of control brain and compared where it was greater in experiment group --> Greater activation in HC: dentate gyrus of anterior HC --> More experienced taxicab drivers had a greater volume of HC--> the more they used their system, the larger their HC grew |
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RESPONSE-RECOGNITION MEMORY TASK |
-Animals rewarded for repeating the same movement from one task to another -Same action made as first trial= reward given -Motor memory task -Only damage to basal ganglia caused deficit; important for skill learning motor movements --> PARKINSON'S DISEASE PATIENTS suffer motor problems and struggle with mirror-tracing task, cannot learn as well as any other individual |
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PRIMING + THE CORTEX |
Demonstrate some sort of recall of implicit memories based on how readily available they are for conscious declaration Ex: Complete the following word- Sta____ -In contrast to skill-testing, priming is not compared to damaged areas (like HC or basal ganglia damage) -In fMRI studies, perceptual priming tasks (looking at something and trying to recall its identity; striate & extrastriate activation-occipital & temporal lobes; right (no need to remember where info cam from)) activate different parts of brain than conceptual priming tasks (left frontal cortex activation) |
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PAVLOVIAN CONDITIONING |
-learning association between events in environment & action -Pavlov trained dogs to salivate at bell sound or sight of light -CEREBELLUM responsible; eye blink reflex where u can condition people to blink reflexively if you puff air in their face and associate it with the sound of a bell |
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Severe impairment of memory STUDY GUIDE |
AMNESIA |
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Difficulty in forming new memories beginning with the onset of a disorder STUDY GUIDE |
ANTEROGRADE AMNESIA |
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A structure located at the back of the brain, dorsal to the pons, that is involved in the centralregulation of movement and in some forms of learning. STUDY GUIDE |
CEREBELLUM |
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To fill in a gap in memory with falsification. Often seen in Korsakoff's Syndrome. STUDY GUIDE |
CONFABULATE |
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The first process in the memory system, in which the information entering sensory channels ispassed into STM. STUDY GUIDE |
ENCODING |
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The second process in the memory system, in which information in short-term memory istransferred to long-term memory. STUDY GUIDE |
CONSOLIDATION |
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A A memory that can be stated or described. STUDY GUIDE |
DECLARATIVE MEMORY |
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A test in which the subject must respond to the unfamiliar stimulus in a pair of stimuli. STUDY GUIDE |
DELAYED NON-MATCHING-TO_SAMPLE TASK |
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Memory of a particular incident or a particular time and place. STUDY GUIDE |
EPISODIC MEMORY |
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A form of nonassociative learning in which an organism becomes less responsive followingrepeated presentations of a stimulus. STUDY GUIDE |
HABITUATION |
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A medial temporal lobe structure that is important for spatial cognition, learning and memory. STUDY GUIDE |
HIPPOCAMPUS |
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A memory disorder, caused by thiamine deficiency, that is generally associated with chronicalcoholism. STUDY GUIDE |
KORSAKOFF'S SYNDROME |
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The superior performance seen in a memory task for items at the start of a list. It is usuallyattributed to long-term memory. STUDY GUIDE |
PRIMACY EFFECT |
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A memory that is shown by performance rather than by conscious recollection. STUDY GUIDE |
NONDECLARATIVE MEMORY |
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The superior performance seen in a memory task for items at the end of a list. It is usuallyattributed to short-term memory. STUDY GUIDE |
RECENCY EFFECT |
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The third process of the memory system, in which a stored memory is used by an organism. STUDY GUIDE |
RETRIEVAL |
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Difficulty in retrieving memories formed before the onset of amnesia. STUDY GUIDE |
RETROGRADE AMNESIA |
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Generalized declarative memory, such as knowing the meaning of a word. STUDY GUIDE |
SEMANTIC MEMORY |
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A form of memory that usually lasts only seconds, or as long as rehearsal continues. STUDY GUIDE |
STM |
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The classical serial recall function is... STUDY GUIDE |
DECLINING |
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There are several successive processes in memory formation; the first stage is called... STUDY GUIDE |
ENCODING |
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NONASSOCIATIVE LEARNING |
Relatively permanent change in the strength of a single stimulus due to repeated exposure of a stimulus |
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H.M.’s performance on the mirror tracing task showed that he could acquire a kind of_______ memory. STUDY GUIDE |
LTM |
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Which of the following brain regions is not one of the prominent sites of damage inKorsakoff’s syndrome? STUDY GUIDE |
HIPPOCAMPUS |
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HM suffered from uncontrollable seizures, so doctors performed surgery on him to remove his... STUDY GUIDE |
ANTERIOLATERAL TEMPORAL LOBES |
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_______ is the process of acquiring new info & ____ is the ability to store & retrieve that info STUDY GUIDE |
LEARNING MEMORY |
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The form of amnesia called _________ amnesia is common after brain trauma and results inthe loss of memories formed up to a year before the injury. However, after his surgery, HenryMolaison lost the ability to form new memories, a condition known as _________ amnesia.Henry was unable to store new information for more than _________. His surgeon had removedthe _________ and most of the hippocampus from _________ of his brain. STUDY GUIDE |
RETROGRADE AMNESIA ANTEROGRADE (HM- forming new memories) HM was unable to store new info for more than a few minutes Surgeon removed the amygadala and most of the hippocampus from both hemispheres of his brain |
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Memory information that we are aware of accessing—facts, words, and so on—is referred to as_________ memory. It is assessed using explicit tests, and in general it is concerned with the“what” questions of memory. Learning that is not subject to conscious recall, such as riding abicycle, is called _________ memory, and it is examined using implicit tests; in general it isconcerned with the “how” questions of memory. STUDY GUIDE |
DECLARATIVE = facts, words NONDECLARATIVE= |
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The experiments with monkeys, together with HM's case, indicate that we need at least one intact MTL, including the HC, in order to make new declarative memories.. But the hippocampus isn’t the only brain structure needed for new declarativememories. Damage to the _________ can also cause amnesia. STUDY GUIDE |
MAMILLARY BODIES |
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Korsakoff’s syndrome is caused by a _________ deficiency. The disease is especially prevalentin people who abuse alcohol. These patients exhibit amnesia and fill in gaps in their memorywith false information, a process called confabulation. Korsakoff’s patients often fail to recognizeor sense any familiarity with some items, even when repeatedly presented, and frequently denythat anything is wrong. Degenerative damage to the dorsomedial thalamus and the _________is commonly seen in these individuals. STUDY GUIDE |
THIAMINE MAMILLARY BODIES |
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All three kinds of memory skills (i.e., sensorimotor, perceptual, and cognitive) appear to beimpaired in people with damage to the _________. Neuroimaging studies have shown theimportance of this structure along with the _________ cortex and the _________ forsensorimotor skill learning. |
BASAL GANGLIA MOTOR CORTEX CEREBELLUM |
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If you learn a list of words, the likelihood that you will recall those from the beginning of the list iscalled the _________ effect, and the likelihood that you will recall those at the end of the list iscalled the _________ effect. STUDY GUIDE |
PRIMACY RECENCY |
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LEARNING |
Change in behavior of an organism happening thru learning as a result of previous experience should be represented by cell changes in neurons or in connections between neurons |
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STEPS OF BRAIN DEVELOPMENT |
NEUROGENESIS CELL MIGRATION CELL DIFFERENTIATION *not numbered in order* |
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What indicates learning when you look at the brain? |
-Change in synaptic connections, stronger synapse networks -->Donald Hebb: a connection between 2 neurons is strengthened if both neurons are active in the same time & space; connections will be weaker if they don't =cells that fire together, wire together -Learning reflects both physical & structural changes that happen to a neuron or how they reflect physiological changes about how they are active in the same time & space |
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When an axon is releasing NTs, the dendrite should be________ |
DEPOLARIZING |
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A dendrite & axon firing together will strengthen their connection and most likely change their... |
...synaptic connection |
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Plastic changes at synapses can be either ____ or _________ |
PHYSIOLOGICAL STRUCTURAL |
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If we want to measure physiological changes, what part of a neuronal response would we measure? |
NT RELEASE APs, GPs NEURON FIRING RATE |
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Learning at the NEURONAL LEVEL |
A stimulus from a neuron produces a typical response from the neuron to which it connects EPSP (GP) changes first -APs are very limited to how much they can be modified with experience -max. limit if spike rates is 1000-1200 spikes per second -APs don't vary in magnitude -EPSPs are first relayed from dendrites; record them to learn change |
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If we induce a paradigm in which we continuously send APs down an axon, and record from the cell body the EPSP changes..... |
If that induces a signal induced with a certain frequency of time, repeated stimulation through one axon while recording another leads to a change in EPSP such that it gets bigger with repetition |
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Wiring together means that the same signal being sent from the same axon results in... |
...a larger depolarization of the dendrite it is connected to --> Physiologically, learning reflects changes in EPSPs |
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If one axon only sent weak/irregular signals to a connecting neuron, and did often not produce a depolarization in the neuron it was connected to, we see a... |
...decrease in size of EPSP in neuron -if connection strength is weak between 2 neurons -learning + forgetting thru synaptic connections --> weakening synaptic connections is important in learning + development (synaptic pruning thru 3-20 mostly, and happens throughout life) =strengthening connections & weakening them |
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The response of a neuron depends on... |
...the frequency that one neuron excites another |
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Pre-Synaptic Cell Modification to Increase Learning |
-Inside axons are vesicles containing NTs (signal) --> More NTs being released with each synaptic event increases amount of learning that takes place -->initial stages of learning shows this |
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Post-Synaptic Cell Modification to Increase Learning |
-Amplify reception of signal, modify amount of receptors which will pick up more present signal --> in long term, persistent increase in reception of signal (increase in EPSP) reflects learning =DEPOLARIZATION from one state of depolarization to another greater state |
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ERIC KANDEL |
-No one had ever been able to link a change in neuron to a change in behavior before him--> Nobel Prize Winner -Worked with Aplysia (marine snail) because they are giant & can demonstrate the most basic forms of learning that simple creatures can perform (NON-ASSOCIATIVE LEARNING) |
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NON-ASSOCIATIVE LEARNING |
-Pavlov associated a bell with a food stimulus to salivate whenever food was to come -Development of basic instinctual reactions in your environment -2 different styles: SENSITIZATION & HABITUATION |
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SENSITIZATION NON-ASSOCIATIVE LEARNING |
increased response to stimuli following the presentation of a prominent stimulus ex: loud sound; strong smell; injury (pain afterwards) |
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HABITUATION NON-ASSOCIATIVE LEARNING |
decreased response to a stimulus following the repeated presentation of that stimulus ex: Loud sound; strong smell |
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Sea slugs demonstrate ___ ___________ ________ __________ that humans all have |
non-associative learning reflexes |
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BABINSKI REFLEX |
-Baby will retract its foot upon getting tickled -Aplysia (sea slug) will do this as well to avoid getting eaten by predators (protection of their organs) |
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GILL SIPHON WITHDRAWAL REFLEX (GSWR) |
-Give aplysia electrical shocks to teach it that the world is a dangerous place -touching the siphon end of it will trigger a siphon withdrawal reflex --> tells scientists if the snail has formed a memory -the longer it remains retracted = an indication of learning -an on-guard siphon stays retracted 4x as long as a naive amplysia =SENSITIZATION; increased response |
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Sea Slug has a simple ___________ system associated with it |
NEUROLOGICAL SYSTEM =Model organisms to study neuroscience due to oversimplified CNS *has 20k neurons; invertebrates have large enough neurons to see with the naked eye that span 1mm in width* --> harder to do so with mammals |
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GILL SIPHON WITHDRAWAL REFLEX Simple Connections Between Sensory & Motor Response |
SIPHON RETRACTS + GILL WITHDRAWAL (to enclose siphon) --> SENSORY & MOTOR systems in place; 1 single connection -stimulus sent thru siphon connected to one sensory neuron that connects to one motor neuron that creates this gill withdrawal reflex |
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Measuring Length of Response of GSWR |
-Touch by tactile stimulus Day 1, Trial 1: 20s -Repeated exposure= animal starts to ignore it even on day 1 -Last trial= habituation has started to take place and responses are 5s or under Day 2=15s -Reactions more quickly approach 5s Each trial has virtually no reaction in the end= LTM |
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Measuring Length of Response of GSWR NEUROLOGICAL EXPLANATION |
-Pre- and Post-Synaptic Neurons dissected and APs were inserted into sensory neuron -Response from motor neuron changes with habituation -Same electrical current given each time --> as habituation continues, motor neuron no longer responds as greatly = EPSP decreasing in strength --> increasing sensitization = increased EPSP |
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CHANGES IN LEARNING REFLECT CHANGES IN ________ ACTIVITY |
SYNAPTICON -->Eric Kandel |
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CATARACTS |
*Changes in protein or crystalline structure of the lens that prevent light from passing thru it, scattering light in a certain way, affects quality of light entering into one eye* -->Eyes cannot work together to create a picture of the world as one eye does not see equally =experience--> drives how connections take place |
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STRUCTURAL CHANGES OF PLASTICITY |
If an eye is deprived of vision by cataract or otherwise, it will be less stimulated in general Ex: eye with cataract; will not be stimulated as much inside of visual cortex as much as a regular eye would receive normal visual stimulation -Lack of activity= reflected in lack of representation in primary visual cortex --> Neurons in deprived eye appear smaller and do not connect in the same way to the deprived eye --> Good eye has better connections, connects with more cells & occupies more space in the brain |
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Primate Experiment--> Tracer Injected Into Eye |
-Primate injected w tracer into one eye so that it is carried back to visual cortex and blackly stains any cell connected with that eye -Zebra-like pattern of visual field alternating between left & right eye -Visually deprived primate injected w tracer into deprived eye =very few cells with connections; majority of other cells in visual cortex connect with non-deprived eye *BIG STRUCTURAL CHANGES IN SYNAPSES* |
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EFFECTS OF ENRICHMENT ON NEURON STRUCTURES STRUCTURAL CHANGES OF PLASTICITY |
Housing rats: -Standard Condition- basic necessities --> Less neurons -Enriched Condition- given toys and a play environment -->More branches in neurons, different types of branching -->More 3rd, 4th, 5th connections Impoverished Condition- deprived circumstances -Loss of 3rd, 4th, and 5th connections *Look at how far branches spread out or see how many branches there are (primary, secondary order)* You can measure changes in EPSP to show differences in learning; structurally- measure order of branches |
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MUSICIANS' LEFT HAND AREA IN MOTOR CORTEX |
(Left hand usually responsible for playing strings) -Musicians = Increased grey matter volume in motor cortex --> Much larger than those who are not musicians -->In front of precentral gyrus- see if there is an overrepresentation |
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Case Study: Woman Blind From Birth |
-Grew up reading braille and transcribed that information -Suffered from a stroke impacting occipital cortex, made a full recovery, but could no longer feel braille, felt as if she had winter gloves on, no longer had the precision --> No damaged sensory cortex, but her visual cortex was helping her to feel |
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TRANSMAGNETIC STIMULATION |
-put magnetic coil over brain region responsible for moving the targeted muscle (hand/ forearm) -delivers magnetic pulse -arm twitches, measured by electrodes *increases activity in different areas* *you can also disrupt areas so that you are unable to speak, for example, if done over Broca's area* |
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TRANSMAGNETIC STIMULATION TEST ON BLIND PEOPLE |
*Tactile discrimination performance task, measure amount of errors* -->Without TMS= few errors -->TMS applied to sensorimotor cortex= both groups are affected, but sighted are more affected --> TMS applied to occipital cortex= sighted are less affected, blind preform badly in this task *ability to feel of those blind from birth relies on occipital cortex* -->heightened sense of touch |
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PHANTOM LIMB NEUROPLASTICITY |
*Input from the face is innervating a part of the brain* -->Latent connections already present that are ready to be activated like troops (activated in childhood during when you have massive synaptic connections that need to be refined) -->Plasticity of massive degrees is possible much later in life if dramatic events occur -->The part of the brain responsible for left hand is hungry for new sensory input, so the face area next to the hand invades this vacant space -->Signals are interpreted as coming from the face due to massive reorganization of sensory pathways in brain |
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When 2 neurons are active in the same time & space, how do they know so that they know they fire together? |
*many of these changes in long-term learning happen on post-synaptic side* -->looked at receptors that played a role in EPSP |
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NMDA RECEPTOR |
*Binds NT glutamate but does not play a significant role in the depolarization of neurons* -->not permeable to Na ions which permit depolarization to happen -->bind glutamate, open for ~100ms, don't allow ions to pass through as it has a Mg ion blocking the path, attached to NMDA receptor -positive Mg ion drawn into receptor as much as possible because of the inner negative charge; not small enough to pass= BLOCKAGE -Permeate Ca2+, not Na+ to pass -->only if NMDA and non-NMDA receptors work together; both x glutamate to open; blockade prevents Ca2+ to go thru NMDA channel; Na+ passes thru non-NMDA channel= depolarization; Mg ion removed as inside of cell is more positive now; Ca2+ goes thru |
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non-NMDA RECEPTOR |
*Binds NT glutamate and causes an EPSP -glutamate binds, causing Na to rush through -induces EPSP, which will trigger an AP if strong enough |
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NMDA RECEPTORS require 2 distinct conditions to occur to allow Ca2+ to flow through |
1) Glutamate binding -->presynaptic release from a neuron 2) Post-Synaptic depolarization -->own neuron must be depolarized *When both are firing together, NMDA channels allow Ca2+ to permeate through* |
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Mg+ ions are only released if... |
...non-NMDA receptors depolarize the neuron first |
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Ca2+'s ROLE |
*Large influx at NMDA receptors activates a variety of intracellular enzymes that affect AMPA receptors* |
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CaMKII |
*Activated by Ca2+ influx* Takes AMPA receptors & causes their insertion into the post-synaptic membrane -->Leads to increase in depolarizing strength |
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Ca2+ influx modifies the AMPA receptors such that... |
...AMPA channels stay open longer & increase conductance of Na+ & K+ ions -As much as ~200ms |
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Ca2+ influx causes the release of things like gasses |
*NITRIC OXIDE & CARBON MONOXIDE* Released by Ca2+ entry in post-synaptic membranes; permeate in a retrograde manner in pre-synaptic membrane, increase amount of NT release (facilitate it) |
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Ca2+ influx additionally causes... |
...transcription & translation of a protein in genes relevant for synaptic function |
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CREB |
When stimulated, increases amount of transcription & translation in a protein *only thru Ca2+ stimulation* *TURNS STM INTO LTM* |
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Tim Tulley Testing Memory Skills of Fruit Flies |
-Shocks flies at their feet and associates a chemical smell with the shock -There are 2 tubes, if the flies remember the unpleasant chemical smell then they will go into the first tube to avoid it -Flies avoid the smell *In order for the fly to form a LTM of this odor-shock presentation, they have to practice repeatedly* --> with 10 training sessions of odor-shock crammed together= does not form a LTM, to wait 24 hours between sessions means flies would forget -->15 minutes is optimal interval --> There must be a rest interval in between each one to form a LTM --> They cannot learn from a single experience *Fruit flies are injected with CREB & given red eyes for easy identification, most CREB flies formed LTM after cramming and after only one session* =FUNCTIONAL EQUIVALENT OF PHOTOGRAPHIC MEMORY |
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MEMORY DRUG |
*Research focus on enzymes that turn CREB on* -Protein Kinases, when active, require energy from ATP -cAMP is main source of energy required to activate CREB --> broken down fairly quickly so that CREB is not overly stimulated |
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To keep cAMP working more than it normally would, enhance What would lead to more CREB stimulation? |
*KEEP cAMP working more than it normally would* -->enhances PROTEIN KINASE A activity |
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PHOSPHODIESTERASE INHIBITOR 4 (PDE4) (ROLIPRAM) |
*degrades cAMP into inactive form* -Used to treat depression -Is an MAOI -inhibitor of depression -Promotes NE release and reduces breakdown of cAMP, keeping it open and longer for more than usual -Improved LTM -Increased WAKEFULNESS -Increased NEUROPROTECTION -Promotion of AXONAL REGENERATION -Functional recovery of spinal cord *INCREASES MEMORY* |
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ROLIPRAM EFFECTS |
-LOW BP -DRY MOUTH -CONSTIPATION -HEAD ACHE *pros must outweigh cons of pill (side effect)* |
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A synapse that is strengthened when it successfully drives the postsynaptic cell. STUDY GUIDE |
HEBBIAN SYNAPSE |
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An enduring form of memory that lasts days, weeks, months, or years and has a very largecapacity. |
LTM |
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A neurotransmitter that is released by the postsynaptic region, diffuses back across thesynapse, and alters the functioning of the presynaptic neuron. STUDY GUIDE |
RETROGRADE TRANSMITTER |
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NMDA RECEPTORS appear to be essential for the formation of_______ memories |
LTM |
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LONG-TERM POTENTIATION (LTP) is... STUDY GUIDE |
...a stable & enduring increase in the MAGNITUDE of the response of neurons |
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Hebbian Plasticity is basically.... (A phrase) STUDY GUIDE |
"Cells that wire together, fire together" |
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At a glutamatergic synapse of the sort found in the hippocampal formation, moderate amountsof activity will cause activation of only the postsynaptic _________ receptors. In this condition,_________ receptors are blocked from mediating a response to the glutamate by the presenceof _________ ions, which act like a cork, blocking the _________ channel in the receptor. Iflarge amounts of glutamate are released, however, the action of the _________ receptorsdepolarizes the postsynaptic membrane enough to dislodge the _________ “corks,” allowingthe _________ receptors also to respond to the glutamate. This results in the opening of the_________ channel and the influx of a large number of _________ ions. The large influx of_________ then activates a variety of intracellular enzymes that affect AMPA receptors inseveral important ways. So, we can say that the _________ receptor is both voltage-gated andligand-gated—both conditions must be present in order for the receptor to be fully active. STUDY GUIDE |
non-NMDA (AMPA) RECEPTORS NMDA RECEPTORS Mg2+ Ca2+ non-NMDA (AMPA) RECEPTORS Mg2+ NMDA Ca2+ Ca2+ Ca2+ NMDA |
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Presynaptic changes are seen in long-term potentiation. When the postsynaptic cell is stronglystimulated, an intracellular process causes the postsynaptic cell to release _________. Thistravels back across the synapse and induces the presynaptic terminal to release _________,thereby strengthening the synapse even more. STUDY GUIDE |
RETROGRADE TRANSMITTER MORE GLUTAMATE** |
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LTP in area CA1 may be blocked by drugs that are _______ antagonists. STUDY GUIDE |
NMDA ANTAGONISTS |
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NMDA RECEPTORS appear to be essential for the formation of _____ memories. STUDY GUIDE |
LTM |
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Synaptic plasticity can be demonstrated in relatively simple organisms like theAplysia. Short-term habituation of the gill-withdrawal reflex to repeated stimulation of thesiphon has been connected with... STUDY GUIDE |
a decrease in the amount of neurotransmitter released at the sensory-motor synapse (HABITUATION) |
