PSC 130 Final

Sleep and memory

Observations during sleep - inhibition of sensory and motor activity - cycles of REM related to vivid dreaming, wake up naturally from REM, periods of REM get longer throughout each cycle of night - Slow Wave Sleep (SWS) every 90 minutes

Overview of R & F

Recollection/R - a slow search for qualitative elaborative info (ex: when, where) - Critically supported by hippocampus and also parahippocampal cortex - broader recollective network and context specific regions are engaged Familiarity/F - a fast retrieval of item strength (ex: what) - Dependent on perirhinal cortex

Dementia

- A progressive cognitive decline beyond what is expected with normal aging - An umbrella term for many disorders: Alzheimer's, Parkinson's, Huntington's, semantic dementia) - 15% over 65 exhibit some form of dementia - 25-47% by age 85 - Correlational relationship between pollution and dementia (idea that diesel particles might be able to diffuse through BBB) ONE STUDY ONLY

Alzheimer's disease (AD)

- A progressive, degenerative disorder associated with profound memory and language impairments - Death 3-10 years after onset - Poor memory is NOT indicative of AD; but a significant decline in memory over 3 months is a symptom

Hebbian learning and the cortex

- A synapse between two neurons is strengthened when the neurons on either side of the synapse (input and output) have highly correlated outputs - Cells that fire together wire together - Hierarchical organization of the cortex is key

Conditioning in amnesia

- Delay conditioning (present CS and US at same time) was normal in amnesiacs - Trace conditioning (present CS and delay US slightly) was impaired in MTL patients - inserting even a very brief 1 sec delay between CS and US makes the task MTL dependent - fMRI in healthy subjects show that cerebellum is involved in both trace and delay conditioning - fMRI shows the hippocampus is critical for trace conditioning

Semantic Demensia (SD)

- Deterioration of anterior temporal cortex (generally L) including perirhinal cortex and more anterior structures - Deterioration of semantic knowledge (deficits in word and picture naming, sound-object matching) with relatively preserved explicit memory - Can present them with object, can remember being shown the object but not the name or function

Perceptual identification task

- PIM test - study words either via reading them or generating opposites - test via recognition or perceptual identification (words flashed on screen, words studied seemed to be on screen longer) - generation helps recognition but hurts PIM because it is a visual form of memory - no visual memory for word, no priming, no generation capability - crossover dissociation between implicit & explicit tests

MTL Cellular Activity Summary

- Hippocampus contains place, time, and possibly concept cells - Entorhinal cortex contains boundary and grid cells - Neurogenesis within the DG may support or facilitate formation of new episodic memories

Recollection Network

- Hot spots of activity when people are recollecting - Hippocampus and parahippocampal cortex are not the only structures involved in R - Angular Gyrus (lateral parietal cortex) involved in attention and/or recollective content; lesioning this are doesn't cause amnesia and can fully recollect, but activation is observed in area surrounding the lesion suggesting the function may be recovered by other brain areas - Retrosplenial cortex/posterior cingulate (medial parietal cortex) involved in contextual/spatial details and navigation (part of dorsal stream) - Medial prefrontal cortex (mPFC) involved in monitoring the output of retrieval, evaluating if its the right kind of information, involved in confabulation Content specific recollection activity - the brain regions involved in encoding an episode are partially reactivated when that episode is later remembered - true for visual and auditory memory

Work fragment completion task

- PIM test - study list of words under a cover story - test via recognition or completing a fragment (implicit) - forgetting rates are slower for PIM - dissociation between implicit & explicit tests attention based - study words under full or divided attention - test implicit vs explicit fragment completion (explicit: cued recall, use studied list to complete fragment) - implicit memory unimpacted, thus does not require attention - another dissociation of implicit & explicit tests

Mere exposure effect task

- PIM test - study irregular polygons 5x each for 1 ms -test 1 forced-choice recognition, present two polygons, which one was in the list? 49% correct by chance bc no explicit memory in 5 ms - test 2 forced-choice preference, present two polygons, which one do you like more? 61% preferred studied items - prior presentation can lead to a preference for items even without any explicit memory - dissociates implicit & explicit memory tasks attention based - study printed product ads under full or divided attention - test 15 min (immediate) or 1 week (delayed) - dividing attention and delay decreased explicit memory but not implicit memory - still displayed preference towards these ads under divided attention - dissociates explicit from implicit memory

False fame effect task

- PIM test - study list of nonfamous names disguised as pronunciation task - 24 hour delay or immediate test - test fame judgements of previously "studied" and new nonfamous names - perceived previously studied nonfamous names as more famous - false fame effect only seen after a delay bc after 24 hrs, start relying on familiarity bc decay in memory - recollection seems to decrease faster than implicit memory

Huntington's disease (HD) and Parkinson's disease (PD)

- Subcortical dementia associated with motor problems, slowness of thorught & planning problems - relatively preserved language and explicit memory - Atrophy deep w/in brain; basal ganglia (HD - caudate nucleus, PD - substantia nigra) HD - involuntary motor anomalies, genetic, rare; cognitively intact PD - tremor at rest (minimized by focusing), motor planning/coordination/controlling impaired

Binding of Item and Context information (BIC) model of R & F

- Ventral visual steam brings information about "what" (item, object, thing) to the perirhinal cortex - Dorsal visual stream brings information about "where" (context info) to the parahippocampal cortex - Information travels through the entorhinal cortex to the hippocampus which binds together information (item and context) to understand the what and where of the event and create a complete memory - Recollection (R) can occur if the hippocampus has linked the what and where of the event together - Perirhinal cortex is more involved in F along with encoding and retrieval of information to make familiarity judgements - Parahippocampal cortex is more involved with R - Accounts for lesion data and imaging studies

Anterograde amnesia

- explicit memory deficits for information occurring AFTER the trauma - Patient NA displayed AA characteristics - Damage to left thalamus - Verbal skills and perceptual skills intact - Verbal LTM is profoundly impaired (story info recall) - Visual LTM was intact (diagram recall) [preserved in R hemisphere]

Retrograde amnesia

- inability to recall events/info that occurred prior to trauma - can be flat (remember nothing before) or graded (just can't remember a few years, rare)

Neurogenensis and its effects

- the growth and development of neurons - observed growth of new neurons in DG of rats that interconnected with nearby neurons in entorhinal cortex, eventually died off - hypothesized that these "baby neurons" serve to help create new episodic memories - 1-6% cell turnover per month - Neurogenesis is decreased by stress, depression, and normal aging (explains decline in hippocampal volume) - Neurogenesis is increased by exercise, antidepressants (Prozac), ECT, and extensive hippocampal dependent learning (use it or lose it!) - Chronic stress reduces DG neurogenesis but the deficits appear to recover Does it occur in humans? 1) Autopsy of hippocampus post mortem - thousands of immature neurons in DG, observed throughout lifespan 2) Another autopsy of hippocampus post mortem - new cells only observed in first year of life * Contradictory, thus we are not really sure if neurogenesis occurs in humans

Main points for aging

1) Deficits in R, working memory, and processing speed 2) Preserved F, perceptual implicit, conceptual implicit, and skill learning 3) Hippocampal, lateral frontal and anterior white matter atrophy, hippocampal decreases and frontal increase in activation

Studies of healthy aging

1) Aging and explicit memory - recall is more disrupted than recognition by aging - associative recognition is more disrupted than item recognition - aging disrupts explicit memory (recollection?) 2) Effects of aging on R & F - aging selectively disrupts R but doesn't impact F 3) Healthy aging reduces R but not F-based recognition 4) Review of implicit memory in aging; majority of studies showed: - Preserved perceptual implicit memory in aging - Preserved conceptual implicit memory in aging - Displayed evidence of priming 5) Procedural memory over long delays - young and elderly showed learning on procedural task & both exhibited comparable savings over 2.3 year delay - normal procedural memory in aging - note: FEW COMPARABLE STUDIES

Studies on brain changes in AD

1) Atrophy and hypometabolism (reduced activation) throughout temporal, frontal, and parietal lobes; decay in volumes of entorhinal cortex --> hippocampus --> frontal cortex --> parietal cortex --> whole brain 2) PET scan study indicates cell loss is marked by plaques and tangles (w/in cell protein degradation) - Tau tangles is linked/correlated to clinical symptoms of demetia (NOT CAUSATION) 3) Monitoring tau in human cerebral spinal fluid in adults 30-60 yrs old during one night of normal sleep and one night of sleep deprivation - sleep deprivation led to an increase in tau and beta-amyloid plaque - failure to clear tau tangles during sleep may be related/leading to AD? - EFFECT DRIVEN BY TWO SUBJECTS, MORE RESEARCH NEEDED 4) Hippocampal and entorhinal cortex atrophy in AD - AD is related to very early atrophy in the hippocampus and EC - atrophy of EC may be observed even earlier and is more predictive of AC

Impairments in amnesia

1) Categorization/perception in amnesia - subjects presented with several items and must identify the odd one out - patients were normal on the color taks - Hippocampus lesions displayed impairment on scene differentiation but normal on others - Hippocampus + perirhinal cortex lesions (MTL) displayed impairment on faces, objects, & scenes - Hippocampus is involved in processing complex spatial information - Perirhinal cortex is involved in processing complex objects * this undermines the idea that hippocampus is memory and perception is done somewhere else 2) Impairments in visual STM - STM color-location change detection task showed hippocampal damage does NOT disrupt visual STM - STM color-location color wheel task showed hippocampal damage DOES disrupts visual STM - Thus the hippocampus may be necessary for remembering precise visual STMs

Evidence challenging Memory Systems Models

1) Conceptual implicit memory - study of exemplar generation, studied words, test prompted to name words in a specific category, likelihood of study words being used is high - Perirhinal damage (MTL) eliminates conceptual implicit memory but hippocampal damage does not - Perirhinal activation predicts conceptual implicit memory and thus in involved in CIM 2) Spatial implicit memory - study of context cuing, studied images and told to find the target "T" and determine whether it was facing L or R, some images were repeated - Response time is faster for repeated than novel arrays, even when recognition for the repeated array is at chance - Implicit learning of complex spatial arrays 3) Context cueing in amnesia (hypoxia & encephalitis), study tested spatial implicit memory - Hippocampal damage does not disrupt context cueing - Extensive damage to MTL disrupts context cueing - Parahippocampal gyrus is critical for learning of spatial configurations 4) Encoding activation related to context cueing and recognition (cueing effect) - Repeated arrays led to REDUCTION in perirhinal activation (region was not related to recognition memory) - Recognition memory was related to hippocampal activation (region was not related to spatial cueing effects) - Perirhinal cortex is involve in context cueing

Types of RA memory tests

1) Crovitz test - cued recall of remote events constrained to specific period in lifetime (amnesiac period), patients recalled very few events [problem: subject variability & false memories] 2) Dead or alive test - faces/names of people who died in different time periods [problem: subject might not know these individuals even if they were alive during that time] 3) Autobiographical memory interview - autobiographical & personal semantic memory from childhood, midlife & adulthood, cued to describe several memories from each life period and scored on # of details [problem: did they actually encode these memories after the trauma?]

Functional changes of aging

1) Decreases in hippocampal activation related to R; perirhinal activity related to F appears normal 2) Increases in brain activity in aging - side note: left is verbal, right is pictoral - increases in frontal activity and more bilaterality

Memory in HD and PD

1) Explicit memory - recall and recognition is relatively preserved early in disease; very aware of their impairments = depression 2) Skill learning - PD and HD patients did poorly on Tower of Hanoi (don't get faster when repeating) task but normal on recognition and recall - PD & HD disrupt skill learning (related to atrophy in basal ganglia) 3) Perceptual implicit memory - PD & HD were normal on stem completion; preserved PIM 5) Conceptual implicit memory - free association task (highly associated word pairs) - HD were normal; preserved CIM 6) STM - PD patients exhibited normal performance on STM verbal tasks; relatively preserved STM 7) Semantic memory - action and object naming - PD deficits in naming, particularly for actions - semantic memory deficits, particulatly for action-related objects? Removal of basal ganglia showed problems in skill learning but intact explicit memory

Memory in AD

1) Free recall - sever recall deficits in AD 2) Recognition - remember/know recognition - deficits in R and F in AD (bc both hippocampus and perirhinal cortex atrophy is observed) - AD affects all forms of explicit memory 3) Skill learning - close to normal performance on mirror reversed reading - procedural memory is preserved in AD 4) Perceptual implicit memory - normal stem completion - PIM is preserved in AD (consistent with neuroanatomy bc basal ganglia and visual cortex not affected by AD) 5) Conceptual implicit memory - word association learning of highly-related pairs, test what word comes to mind - AD performed more poorly than healthy controls - CIM is impaired in AD 6) STM - AD patients exhibit deficits in digit span - STM is impaired in AD (consistent with neuroanatomy bc areas around hippocampus atrophy, disrupting connections, atrophy in PFC as well) 7) Semantic memory - object naming and matching to function; can't identify recipient of tool's action - AD impaired on naming and semantic matching tasks - semantic memory is impaired in AD

Different types (?)/causes of RA

1) Herpes Simplex Encephalitis - patient RFR, severe damage to temporal lobes, severe AA and RA with RA being flat 2) ECT-induced - tested memory prior to treatment then 2 hours after 5 total treatments, severe AA, temporally graded RA (a few years back) RA impact on explicit and implicit memory - stem completion vs cued recall for words encoded just prior to ECT - RA for explicit memory, no RA for implicit memory - dissociate implicit/explicit memory 3) Hippocampal damage - patient WH, selective hippocampal damage, lead to graded RA for semantic info 50+ years old, evidence for Systems Consolidation Theory or that semantic memory can be supported by cortex - lead to flat RA when test requires detailed episodic info, thus episodic memory is not consolidated to context but dependent on hippocampus, remote memories may be remembered/rehearsed so may be supported by cortical memory 4) Patients with isolated RA - Patient TJ, lesions to inferior-lateral temporal lobe (hippocampus preserved), RA with very little AA, isolated RA reflects inferior temporal lobe storage deficit

Implicit learning of new information in amnesiacs

1) Reading speed for repeated/new words and nonwords in controls and amnesiacs - amnesiacs exhibit normal priming for words and nonwords - evidence of priming for new info in amnesiacs (completely discredits Activation Theory) 2) Conceptual implicit memory (fact learning) can happen 3) Semantic learning in childhood amnesiacs (new facts are learned) - implicit memory cannot simply reflect the activation of exiting representation, arguing against Activation Theory

Studies on specialized cells in humans

1) Hippocampal activity during taxi cab navigation task - Cells in hippocampus respond when in specific locations, but perirhinal cortex, amygdala, and frontal cells DO NOT - Imply human hippocampal place cells - Cells in the perirhinal cortex responded to specific buildings regardless of location - Imply human parahippocampal gyrus scene cells - Important for episodic memory 2) Human grid cells? ONE STUDY, probably don't exist - subjects learned 4 invisible object-locations in open simulated space - Grid-like cells seen in EC, hippocampus, and cingulate cortex but NOT amygdala, parahippocampal or frontal cortex 3) Concept cells - activated by different pictures of given individuals, landmarks, or objects in in some cases even by seeing their names

Theories of sleep and memory

1) Interference reduction - sleep reduces the amount of new interfering information encoded into memory (doesn't explain how implicit memory improves during sleep) 2) Memory consolidation hypothesis - sleep leads fragile memory traces in hippocampus to be replayed and thus consolidated in the cortex (consistent with Systems Consolidation) 3) Synaptic homeostasis hypothesis - wakefulness leads to an increase in synaptic strength and activity - Sleep is needed to down-regulate activity to facilitate efficient learning - Weak connections are lost during sleep, increasing signal-to-noise ratio (stronger signals are remembered)

Summary of RA

1) Large MTL lesions lead to flat RA and AA 2) Damage to hippocampus often can lead to graded RA for semantic memory but flat RA for episodic memory 3) RA (like AA) impacts explicit but not implicit memory 4) Isolated RA can be seen with inferior temporal lobe damage

Causes of AA

1) Lesions 2) Blows to the head (affect frontal cortex and MTL) 3) Brain infection via viral encephalitis (extensive MTL damage) [ex: Clive Wearing] 4) Stroke (blockage of blood supply) [lateralized/one hemisphere only] 5) Korsakoff's syndrome aka thiamin deficiency (damage to thalamus and frontal cortex) 6) ECT 7) Hypoxia (brief loss of oxygen, low O2 = cell death in hippocampus) [selective hippocampus damage in mind cases]

Impact of sleep on explicit and implicit memory

1) Mirror tracking (implicit) vs paired associates recall (explicit) tasks - Implicit memory benefits from late REM rich sleep - Explicit memory benefits from early SWS rich sleep - double dissociation of implicit/explicit 2) Memory replay in rat sleep - cortical and hippocampal place cells tracked movements on circular maze run - found similar order activity during SWS - evidence for replay during sleep to consolidate (?) 3) Learn card location associations during a context odor, then sleeping - old or new odor presented during SWS - test memory for card location in and outside of scanner - odor during SWS but not REM increased memory - odor in scanner while asleep led to hippocampus activation (remembering events associated with smell) - evidence for replay during SWS to consolidate/remind (?)

Models of Semantic Memory

1) Neural network model in ATLs - a "hub" that binds visual, lexical, and functional info together - accounts for semantic deficits in SD patients and activation results from semantic tasks 2) Representational-Hierarchical Theory - the ventral stream (posterior visual cortex to perirhinal cortex) supports increasing complex feature conjuctions (low level --> high level concepts)

Cognitive functions preserved in AA

1) Perceptual abilities (visual clarity, color perception) 2) Phonological STM (digit span) 3) Semantic memory (knowledge, language, & IQ) 4) Skill learning (tower of Hanoi, mirror image drawing) - study: artificial grammar learning - subjects (amnesiacs vs controls) studied grammatical strings, tested on grammaticality or recognition of strings - amnesiacs were impaired at recognition but NOT significantly impaired at picking out grammatical items - preserved non-motor skill learning 5) Perceptual implicit memory (word stem completion and mere exposure effects were normal in amnesiacs - PIM is not disrupted by MTL damage (relies on right occipital lobe) 6) Conceptual implicit memory? - study: fact learning (false facts) [Bob Hope's father was a fireman], tested facts - found amnesiacs can learn these new facts even though they don't remember where they learned them from - CIM is at least partially preserved in amnesia - 2nd study: 3 students with childhood hippocampal damage from hypoxia (significant anterior damage), displayed severe memory impairments after many years, yet they graduated from high school - no evidence of memory recovery, thus hippocampal function cannot be taken over by another part of brain - retained the ability to learn semantic info about the world w/o the hippocampus

Sleep Summary

1) REM (and SWS?) related to implicit learning 2) SWS related to explicit memory 3) Replay effects during sleep 4) Reminding during SWS improves explicit memory Theories: interference or consolidation or homeostasis ?

Ways of measuring R and F

1) Response deadline - if R is slow then speeded responses should rely more heavily on familiarity 2) Process dissociation/source memory - item recognition relies on both R & F, whereas source recognition relies more heavily on R 3) Remember/know - subjects can report when they remember and when they just know an item was studied (must rely on truthful responses and subjectivity of a person's recollection) 4) Receiver operating characteristics (ROCs) - R & F can be estimated based on the shape of the ROC (i.e. confidence judgements)

Studies on SD

1) SD patients were impaired at semantic decisions (matching pyramids and palm trees) but normal on episodic memory (which one was presented before); dissociation of semantic and episodic memory 2) PET scan displays SD atrophy in left temporal lobe, struggle making semantic judgements on categories - high level semantic representations in ATL (anterior temporal lobe) 3) Naming objects at basic level led to posterior and anterior temporal activity; naming objects on domain level (living/nonliving) led to only posterior temporal activity - ATL represents complex configurations of feature making up high level concepts

Preserved abilities in AA

1) Simple perception 2) Phonological STM 3) Semantic memory 4) Skill learning 5) PIM 6) CIM (but perirhinal cortex is critical) 7) Delay conditioning (but hippocampus is critical for trace conditioning) 8) Complex perceptual memory (hippocampus is critical for scene perception and perirhinal cortex is critical for complex object perception) 9) Visual STM (but hippocampus is critical for precise visual STM) 10?) Contextual cueing (visual implicit memory) - hippocampus or perirhinal cortex?

Current challenges to the Memory Systems Models

1) Some forms of implicit memory can be supported by MTL 2) Some forms fo perception and STM can be supported by MTL 3) Specialization within the MTL (hippocampus vs perirhinal cortex)

Structural changes of aging

1) age-related declines in lateral PRC and and hippocampus, but little decline in other regions like occipital or entorhinal cortex; volume reduction due to lower synaptic densities (less synapses between neurons) rather than cell death 2) (in nonhuman primates) reduction in frontal and hippocampal thin spines vs mushroom spines, related to delay 3) imaging indicates age-related decreases in white matter integrity, particularly in anterior regions; possible disconnection of frontal cortex and posterior regions (worsening communication) 4) Brain/behavior correlations in aging - hippocampal atrophy is correlated with explicit memory declines - white matter hyperintensities (spots) are related to explicit memory declines (and heart health)

Studies on specialized cells in animals

1) Sparse activity in hippocampus evaluated by Activation Plots - Hippocampal neurons are less responsive and more selective to specific locations and directions than cortical neurons (create good episodic memory) 2) Place Cells - found in hippocampus - respond only when animal is in specific location in space - cells will remap when put in a new space (circle vs. square) - develop slowly 3) Boundary Cells - found in entorhinal cortex and subiculum - respond to borders of walls - maintained when environment changes shape - rare, only 10% EC cells are border - develop very quickly, as soon as animal explores their environment 4) Grid Cells - found in entorhinal cortex - respond to multiple locations forming a hexagonal grid pattern - independent of configuration of landmarks - fire independent of animal's speed and direction - larger scale grid as moving more anterior in brain 5) Time Cells - found in hippocampus - respond to specific times, regardless fo speed, while running on treadmill - thus remember both spatial and temporal context 6) Head Direction Cells - found in EC, subiculum, & retrosplenial cortex - fire when animal's head points in specific direction - not informative for humans because head movement is not constricted by neck

How to reduce effects of aging on memory

1) Stay intellectually engaged; less decreases in structural volume and better memory scores 2) Maintain cardiovascular physical activity; increase in hippocampal volume and memory scores with physical exercise 3) Minimize chronic stressors 4) Maintain brain-healthy diet: unsaturated fats, vitamin E, antioxidants 5) Bilingualism (?) - bilingual speakers had delated onset of AD by 4 years; better at PFC inhibition task

Neural basis of PIM

1) Visual priming involves the visual cortex 2) Priming is related to a decrease in activation 3) No consistent lateralization effects 4) May also involve material-specific regions

Perceptual implicit memory (PIM) tests

1) Word fragment completion 2) Perceptual identification 3) False fame effect 4) Mere exposure effect

Functional characteristics of PIM

1) requires very little attention 2) Slower forgetting than explicit memory 3) Sensitive to perceptual manipulations 4) Not sensitive to semantic manipulations 5) implicit tests are susceptible to explicit contamination

Evidence for neural basis of PIM

1) study incidental encoding of words, test old stem completion vs old stem cued recall vs. new (not studied) stem completion in PET scanner - old stem completions associated with LESS activation in right occipital lobe (visual cortex) than new ones, bc neural priming (easier to recognize stem) - old recall completions associate with GREATER medial temporal lobe activation than new ones, bc using explicit memory (hippocampus) - neural dissociation of implicit/explicit memory 2) study has subjects look at faces; test recognition of faces (explicit) vs fame judgements for faces (implicit) under fMRI - R fusiform face area (FFA) and left occipital regions showed LESS activation for old than new faces in implicit test, bc neural priming - neural priming may be material specific 3) implicit memory preserved in amnesiacs? study intentional learning of word list, test via free or cued recall vs implicit word stem completion - PIM does not depend on medial temporal lobes, instead on right occipital lobe - dissociation of implicit/explicit memory 4) PATIENT MS, removed right occipital lobe for intractable epilepsy, blind in left visual field, study words to be tested via recognition memory or stem completion priming - can use recognition memory but cannot complete stems - right occipital lobe is critical for stem priming but not recognition memory - SINGLE PATIENT 5)Patient with severed corpus collosum and patients with right occipital lobe damage - no deficits on PIM tests in any patient - right occipital lobe does not seem to be necessary for implicit memory, bc left hemisphere supported the priming?? - NO CLEAN DOUBLE DISSOCIATION FOR PIM and explicit memory

Studies dissociating R & F

1) study words (visual or auditory), test words (visually) and R/K/N recognition responses - perceptual match increased F but not R - F relies more on perceptual information than R does (see a word @ study & @ test, more familiar) - dissociates F from R 2) Effects of aging on memory - study list of words, test R/K/N recognition responses - aging reduced recollection but not familiarity - R is more susceptible to aging than F - dissociates R from F 3) LOP effect on R & F - study deep (pleasantness) vs shallow (# syllables) encoding, test recognition confidence via ROC - deep processing increases both R and F, but R to a greater extent - R is more sensitive to semantic elaboration than F - Some manipulations can influence both processes and thus they don't always dissociate 4)Visual masking at test - study list of words, test in two conditions: fluent (flashes word on screen) and control (no flashing of words), then R/K/N response - increasing perceptual fluency increases F but not R - F is more perceptual than R - dissociates F from R - side note: implicit memory/mere exposure effect?`

Cognitive changes in healthy aging

Decreases - speed of processing - working memory - LTM Preservation - world knowledge

Contamination of implicit vs explicit tasks & Evidence

Either test can contaminate the other, subjects figure out the cover story is actually testing memory and try to remember the words Evidence - rating list of words on pleasantness vs counting t-junctions (applying LOP) - test stem completion using the first word that comes to mind - deep LOP increased implicit memory, but its possible that subject might have used explicit memory - use post-test awareness questionnaire to evaluate the strategy used to complete fragment - I used my memory (explicit) vs. just did what you said (implicit) - contamination results in biases - conclude PIM (uncontaminated) is not sensitive to LOP

Hippocampal Circuit

Entorhinal cortex (EC) --> dentate gyrus (DG) --> CA3 --> CA1 --> EC - DG (sparse and rarely active) and CA3 supports sparse and orthogonal representations (episodes), primarily involved during encoding - Information is sent to CA1 and EC for retrieval - Cells only activate for specific actions - Separate neural associations for encoding (EC, DG, CA3) and retrieval (CA1, EC) - Using both mappings at all times to create full picture of the memory - Also called pattern creation and completion (creating = encoding, completion = retrieval)

Implicit vs explicit memory

Explicit - conscious remembering Implicit - unconsciously remembered (blinking, breathing, walking, etc.)

Implicit vs. explicit memory tests

Explicit - tasks that explicitly instruct subjects to use memory Implicit - tasks that do not explicitly instruct subjects to use memory

Functions of hippocampus vs perirhinal cortex

Hippocampus - recollection, scene perception, trace conditioning, precise visual STM Perirhinal cortex - familiarity, conceptual implicit memory, object perception

Evaluating early memory systems accounts with amnesia

MTL function supports an explicit LTM system that is selectively disrupted in amnesia 1) Modal Model - selective LTM deficit leaving STM intact, CANNOT account for behavioral or neural dissociations seen within LTM (implicit vs explicit) 2) Activation Theory - amnesiacs can activate existing representations in LTM (implicit) but cannot create new associations (explicit) - accounts for behavioral & imaging dissociations along with MTL lesions BUT MTL damage should disrupt the implicit learning of new associations (not well represented) [problematic assumption because amnesiacs can make new associations with implicit learning - see flashcard] 3) Episodic vs. Semantic memory model - Smaller box on top for episodic memory, encodes events which are dependent on the MTL, this memory drops off very quickly - Large box for semantic memory, general knowledge about the world, supports behavioral & imaging dissociations along with MTL lesions - Bc both systems can learn, implicit memory can support learning of new info - Assumes only humans have true episodic memory and that young children do not have episodic memory (clearly disproved in studies); limited because how are skill learning & PIM modeled - Modifications: Serial In/Parallel Out Model (perceptual/procedural on bottom, semantic, episodic on top) - encoding is done serially from perceptual/procedural to semantic to episodic and retrieval can be done in parallel from any box 4) Declarative vs Procedural memory model - Declarative box (explicit) for memory that can be declared (knowledge and events), MTL dependent, but slowly consolidated to cortex - Procedural box (implicit) for learning that can't be verbalized or consciously expressed, cortex dependent (bc Cohen & Squire discovered amnesiacs can do Tower of Hanoi but could not remember learning the task) - Separate boxes for semantic and episodic memory - Lesioning of the hippocampus should wipe out explicit memory for events AND ability to create knowledge but you don't completely lose both

Rodent model vs. human studies of R & F

Rodent model - Rats display memory for location of platform in a pool of water; Lesion hippocampus, rats find platform in same amount of time - Measuring rats differentiation between old & new items; Lesion perirhinal cortex, rats prefer familiar & novel stimuli the same and display normal spatial navigation - this literature suggests recollection can occur without familiarity Human lesion studies 1) Collective literature indicates the following: - Hippocampal damage disrupts R - Perirhinal cortex damage disrupts F - Hippo + PC damage disrupts both R and F 2) Encoding activity related to subsequent R & F - study colored words, test recognition confidence (F) and color memory (R) - F confidence increased with perirhinal activity - R was related to greater hippocampal and paraphippocampal cortex activation - indicates hippocampus, perirhinal cortex, and parahippocampal cortex are all involve in encoding 3) Recognition retrieval activity related to Remember and Know responses - Hippocampus was related to R but not F - Perirhinal cortex was related to F but not R - Note that parahippocampal cortex activity at retrieval is often related to R - perfect double dissociation at encoding and retrieval

Impact of sleep/napping on implicit memory

Sleep on Implicit Memory - tested visual texture discrimination (visual perceptual leanring) - improvement in discriminating after sleep but not after awake delay and then sleep - maintained improvement over several nights - sleep deprivation on first night let to no memory enhancement even after 2 nights sleep - performance was correlated with early night SWS and late night REM sleep - sleep benefits implicit memory (SWS/REM?) Napping on Implicit Memory - visual texture learning after napping, tested after nap and 10 hr delay - 60 or 90 minute naps were sufficient to lead to memory enhancement effects (same as whole night sleep effects) - SWS + REM was best

Remember/Know procedure (Tulving)

Three options for subjects to respond with: 1) Remember - if you can retrieve qualitative information about the studied event, such as what the word looked like, its context, or what you thought about 2) Know - if the word is familiar in the absences of recollection, that is, you think it was studied but can't recollect anything about it 3) New - if you think the word was not studied

Familiarity (F)

a relatively fast process whereby familiarity or a "sense of recency" is used as a basis for recognition (i.e. the item seems familiar, so it probably was studied)

Recollection (R)

a relatively slow search process whereby qualitative information about a prior event is retrieved (ex: when, where, etc.)