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What skills are impaired in amnesia?
Verbal learning, so can't do paired associate learning and visual learning so can't do delayed rey figure copy test. In other words episodic memory is impaired.
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What skills are preserved in amnesia?
STM (working), semantic memory and implicit memory which includes classical conditioning, procedural learning and perceptual priming
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What did patient HM have?
Severe anterograde amnesia and retrograde amnesia spanning 11 years before he had bilateral removal of his medial temporal lobes (most damage to anterior hippocampus) during surgery to treat epilepsy
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Why is patient HM unusual?
Usually spatial learning is impaired in amnesia but he was able to recall spatial locations after surgery
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Why is HM considered to be a case of pure amnesia?
Because only new leaning was impaired. All implicit learning and other cognitive abilities were intact.
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Give an example of someone who suffered amnesia after infection with herpes?
Patient EP (Squire et al).
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Why does herpes virus not cause pure amnesia?
It spreads beyond hippocampus. Despite this damage isn't so widespread as it would be in alzheimers disease so other cognitive capacities are not affected.
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Why is the hippocampus vulnerable to herpes infection?
The hippocampus is close to the olfactory and cranial nerve where the virus enters the brain
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What did Clive Wearing have?
Infection with herpes resulting in dense anterograde amnesia so his memory only lasted 20 seconds. Other facilities not affected.
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What is the papez circuit and why is it relevant?
It includes hippocampus, fornix, mamillary bodies and thalamus. Since it is so highly connected to hippocampus, damage to an area in this circuit can lead to amnesia.
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What is one example of how malnurition can result in amnesia?
Korsakoffs syndrome. Alcohol dependency can result in thiamine (vitamine B) deficiency which causes damage to mamillary bodies.
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Which brain areas are damaged in korsakoff's?
Widespread damage. Affects PFC as well as medial temporal lobes so have additional symptoms like confabulations and abulia. Sometimes able to cue memory retrieval.
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What are the 3 roles of the medial temporal lobes?
Episodic memories, explicit memory in all sensory modalities and transferring information to LTM
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What are the 4 areas of the hippocampus?
denate dyrus, CA3, CA1, hippocampus subiculum
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What is the roe of the hippocampus?
For multimodal episodic memories. It integrates information about the same event from the PPA, inferiror temporal cortex and anterior temporal lobe. This allows memory to be associative.
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What is the temporoparietal lobe for and how do we know?
STM, because KF had damage here and he had a tiny digit span
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Wht is the occipital lobe for?
Nondeclarative memory because patient KS who had epilepsy was unable to pass implicit tasks
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When does synaptic consolidation happen?
A few minutes/hours after intitial encoding. This involves making more glutamate for more depolarisation and making more transcription factors so new NMDA receptors can be inserted and growth factors can be made so thicker dendritic spines can form
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When does systems consolidation happen?
This takes days/months/years
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What is the standard consolidation theory?
That neural connections between areas of cortex that connect to the hippocampus eventually form neural connections with eachother after repeated reactivation so damage to the hippocampus need not impair memories that have been reactivated many times
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What is the multiple trace theory?
That the hippocampus alwas stores episodic memory traces so areas of cortex always rely on it but older memories have a greater no. connections to the hippocampus so are more resistant to amnesia
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What does the medial temporal lobe include?
Hippocampus, parahippocampus (which projects to entorhinal cortex and rhinal cortex
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What is the 2 process theory?
That the hippocampus does slow, spatial processing for familiarity and the perirhinal cortex does rapid processing for novel stimuli
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What is the 3 process theory?
That the parahippocampus dpes spatial learning, the perirhinal cortex does object learning (as it is in the ventral stream) and the hippocampus integrates this information.
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What did Hebb find out?
Memories are stored in cell assemblies so connections between related concepts are made and suggested the stronger the connection, the stronger the association
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What is the posterior hippocampus close to so what is it thought to have a role in?
The parahippocampus so related to spatial learning
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What is the anterior hippocampus close to so what is it thought to have a role in?
The entorhinal cortex so associated with sense of familiarity for objects and salience and next to amygdala so elated to emotion
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Why would it be so likely that the hippocampus is for multisensory memories?
It is richly connected to all areas of cortex
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What does Bliss and Lomo's rabbit study show?
That learning happens at the synapse because it is only after a high freq. impulse that a later action potential crates even more synaptic stimulation than before
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Where were place cells first found in rats?
In CA1 (posterior hippocampus). Then found single cells responding to spatial locations in humans here and also found hippocampal volume increase in taxi drivers which supports this
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What is the relational memory theory? (Eichenbarium and cohen)
A general theory that the hippocampus mediates memory for new associations
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What is the episodic memory theory? (Tulvis et al)
That the hippocampus encodes relations within a framework. Evidence comes from knock out mice who can learn associations but can't infer relations between paired associations
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What is the cognitive functional map theory (O'Keefe and Nadel)?
That the hippocampus mediates memory for spatial relations. Most promising evidence comes from knock out mice who have imparied spatial learning for maze task.
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Connectionist models of memory assume processing happens in parallel. What advantages would this have?
Allow infor to be stored in widely distributed networks just by changing the connection stengths and this allows simultaneous information access during memory retrieval
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What are the issues with connectionist models of memory?
Tey don't explain rule based learning an it's not possible to discern between alternative models of the same cognitive processes
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What initially happens during LTP?
When there's a high enough frequency impulse enogh glutamate is released for electrostatic repulion so enough sodium ions diffuse through NMDA receptors to depolarise the postsynaptic neuron.
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What happens when calcium ions enter the postsynaptic neuron during LTP?
These drive chemical and structural changes: more NMDA receptors made and more glutamate produced so more sensitive to changes in the synapse. These short term changes are short lived., lasting a few hours.
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Why is a depolarised postsynaptic neuron a good thing for LTP?
It will be depolarised at the same time as the presynaptic cell during reactivation and because NMDA is a coincidence detector this means the connection between the 2 neurons can increase in strength.
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Why do you not want too much glutamate?
It's toxic which is why it's transmission is blocked by memantine (an antagonist) during late stages alzheimers
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Why is it possible for memory to happen for a single event and can last a lifetime, is separate from other memories but all aspects of the event (the smells, the light) are bound together?
LTP can happen for a single high frequency action potential and can result in lifetime changes during systems consolidation. Just one pathway is strengthened. But strong AND weak pathways are enhanced as long as both are active simultaneously.
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What happens during systems consolidation?
Permanent changes. When there's prolonged influx of calcium ions the proteins that end up being made can lead to transcription factors: more NMDA recptors to form between clefts, more dendrites and more synapses.
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What does synaptic consolidation basically result in?
Changes in mechanisms of synaptic plasticity
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What does systems consolidation basically result in?
Changes in the relative contribution of different brain regions
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Tulving said there are 2 memory systems, explain?
one for episodic and one for semantic which have different neural substrates and different cognitive processes
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Is episodic memory better when young or old?
Episodic better when young, semantic memories better when older
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KC had hippocampal damage resulting in amnesia. What was he still able to do?
Semantic memories like knowledge of tools was still in tact
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Who has a double dissociation with amnesics?
Semantic dementia patients who have damage to anterior temporal lobes because they have preserved episodic memory but a progressive loss of concepts, words and objects
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What eventually happens in semantic dementia?
Damage spreads to the temporal lobes so start to lose episodic memories
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What does the hippocampus seem to do?
For separating out memories and creating unique multimodal memories so is for episodic memory
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What does the anterior temporal lobes seem to do?
For extracting similarities between expereinces and merging memories together to form concepts so seems to be for semantic memory
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How does Tulving's idea of there being 2 memory systems explain semantic dementia?
Unique features seem to be more vulnerable to damage because they don't share connections with other concepts. This also explains the temporal gradient.
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What is the problem with Tulving's theory of parallel processing?
Semantic dementia patients often show preserved old episodic memories and semantic memories learnt early in life. So maybe the hippocampus transfers traces to the neocortex over time.
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What evidence from amnesia is there for Squire's idea that traces might be transferred from episodes to semantic memories?
Recent memories are most severely impacted because when the hippocampus is damaged there is no way to consolidate memories and so you get a temporal gradient
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What evidence from semantic dementia is there in favour of Squire?
People with neocortex damage show a reverse temporal gradient because recent memories are preserved but older memories are lost. This is because hippocampus is still in tact so pre-consolidated recent memories are still available in hippocampus
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What does acquisition of semantic information depend on according to Squire?
On episodic memory
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What did Marshall (2006) find out about sleep for declarative consolidation?
Increased verbal learning after SWS
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What evidence is there that sleep is for consolidation from rats?
Single cell recording from place cells during SWS shows spatial memories are being consolidated
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What did Peigneux et al (2004) find out about spatial memory?
The hippocampus reactivates during SWS in the same way as it did during spatial learning task showing spatial route is reactivated during sleep and there was better memory performance for route the next day
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What did Van Dongen (2012) find out about sleep and sound?
They played a sound during a spatial learning task and when this sound was replayed while pps were in SWS the hippocampus started showing activity which shows conditioned sound could reactivate memories
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According to PDP, how does the hippocampus process information?
It is fast and auto associative. By rapidly binding different elements of an event together there is easy access to all features of the episode. Because only a few neurons code for each feature similar memories can be kept separate
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To associate different elements of an event together the hippocampus must strengthen the weights between the connections. How does this happen?
When input activation and feedback activation fire concurrently, learning takes place.
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According to PDP, how does the anterior temporal lobe process information?
Slowly and strongl encodes similar features shared by different experiences to allow concepts to form
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In PDP anterior temporal lobe encoding weights change slightly each time there's a new experience, what does this prevent?
Catastrophic interference. Over many learning trials as connection weights are adjusted similar activation patterns form similar concepts. This can predict output based on neural activation after output.
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What is the sensory/functional theory?
That appropriate sensory/motor areas store semantic information
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What is the domain specific theory?
That semantic information is stored according to it's category an not property. For abstract concepts there will be distributed coding with not special networks OR distributed-plus-hum view: anterior temporal cortex stores all abstract concepts
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The transfer-appropriate processing assumes that after consolidation you're able to recall memories when..?
When there's overlap between encoding and retrieval
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How do you study transfer-appropriate processing?
BY multivoxel pattern analysis (mPVA). This demonstrates that different brain regions store memories according to concepts because the neocortex activates for recollection after consolidation.
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Accoding to mPVA, what activates before consolidation?
The hippocampus during recollection
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What evidence is there that the hippocampus is for episodic memory?
Amnesic patients can't learn new information. This support both Tulving and Squire
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Why is evidence that amnesics can't learn new information not enough to conclude that hippocampus is necessary for episodic memory?
Unlikely to be the only place for episodic memory and even when the hippocampus is damaged, many amnesics still have some episodics memory (i.e. old memories)
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What evidence is there against Squire that semantic memory doesn't always depend on episodic memory?
Those whove had hypoxia at birth have severe hippocampus damage and have severely impaired episodic memories but are able to learn semantic memories. This supports Tulvings idea of separate systems
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How does Hypoxia case show hippocampus might not be necessary for all declarative memories?
The entorhinal and rhinal cortices are still in tact (unlike in many amnesia cases) so it might be that these areas encode episodic memories necessary for semantic learning...
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How might temporal gradient support Tulving?
Older memories have a different quality in that they are more like semantic memories so might be stored in separate system to rest of episodic memories
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How might temporal gradient support Squire?
Older memories might be more consolidated so more transferred to neocortex than earlier memories still i hippocampus which is impaired in amnesia
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Learning of events involves the hippocampus but..
...it's not the only location to facilitate episodic memories
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There does seem to be a transfer of information from the hippocampus to neocortex but...
Might not be that all information is transferred
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What can vlPCF also be referred to as?
LIFG and Brocas
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What does vlPFC do?
directs attention to the important aspects of an experience and so activates when we know information is going to important to recall later on
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vlPFC functions normally in amnesia. What does activity in this area predict?
Future memory success
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What does PFC contribute to encoding and retrieval?
semantic and episodic control processes
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What happens when vlPFC is damaged?
Deficits in source and recalls tasks requiring strategic control processes
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What does encoding require if PFC is active during encoding?
top-down processing
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left vlPFC activates during verbal tasks, what about visual tasks?
bilateral vlPFC
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What area of PFC is necessary for organisation of working memory?
Dorsolateral PFC
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Posterior PCF aftivates during phonological processing, so anterior part activates for...?
semantic processing
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What is retroactive interference and what is the other kind of interference?
Where new learning interferes with old learning. Proactive interference is where old learning gets in the way of new learning
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How is interference maximised?
recent, many competitors, similar
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How does interference lead to false memories?
Elements of many similar memories are combined
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Why is vlPFC useful for stopping interference?
It resolves competition between similar memories
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What did Badre and Wagner (2005) find out about interference?
Lots of similarity leads to inaccurate recall
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What is important for spontaneous retrieval?
Default mode network
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Why is dorsolateral PFC not specific to memory
It is used for all kinds of monitoring
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The mid PFC is involved in retrieval control. What does the posterior and anterior parts do?
Posterior for implementation of attention, goals and competition resolution so is most associated with success in retrieval. Anterior processes what needs to be retrieved. Right side for retrieval, left side for semantic processing
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In what way is vlPFC selective to goals?
It controls memory recall, suppresses unwanted memories and resolves similar competing memories as different.
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How does vlPFC control retrieval?
Generates activity in visual network of semantic network to control attention during encoding phase. This is why there's more vlPFC activity during harder tasks because more attention is required.
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Why is vlPFC said to do source monitoring?
It puts memories into their encoding context by reactivating the relevant areas during retrieval
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300-500ms after a stimulus is presented there is greater negative voltage in...?
Dorsal PC because this area is involved in momory search and monitoring
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Verbal stimuli elicits activity in what area?
left PPC
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600-1200ms after retrieval there is more activity in...?
Right frontal cortex
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Why do semantic aphasics retrive inappropriate associations but have success when correctly cued?
Because can still encode information since have working hippocampus but have damage in the control network so can't do source monitoring
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What happens in retrieval induced forgetting?
Some associations are strengthened at the expense of others so retrieval improves for some memories while others are inhibited
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Why does vlPFC activity reduce with more repeated retrievals?
Because there is reduction in competition. This is useful because it shows interference has been controlled.
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What is intentiona forgetting?
Consciously controlled, goal-driven suppression of some memories
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What happened in Anderson and Green's (2001) study?
Think-No think paradigm. Fewer no think words were recalld than baseline so able to selectively suppress unwanted info. During no think trials there was reduced hippocampal activity and increased PFC activity.
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When does false memory arise?
Can happen when PFC damaged because no competion resolution so merge competitors.
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Apart from vlPFC what areas are likely to be damaged when people confabulate?
orbitofrontal cortex and temporal lobe because have source confusion and lack of error monitoring so either fail to suppress old memories or retrieve mixtures of competitors in extreme way
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PTSD sufferes are unable to suppress unwanted thoughts. What is thought to be going on?
THere might be faulty functioning in the vlPFC
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How long does consolidation take?
For synaptic: mins-hours as shown when inhibit protein synthesis which disrupts memories for an hour. Systems consolidation lasts days-years as shown by lesions to hippocampus which have an effect from 28 days
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What is the standard consolidation theory?
That the hippocampus transfers memory traces to the cortex
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What is the multiple trace theory?
That even old memories depend on the hippocampus but there are more traces for older memories so these are more durable.
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Card 2

Front

What skills are preserved in amnesia?

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STM (working), semantic memory and implicit memory which includes classical conditioning, procedural learning and perceptual priming

Card 3

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What did patient HM have?

Back

Preview of the front of card 3

Card 4

Front

Why is patient HM unusual?

Back

Preview of the front of card 4

Card 5

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Why is HM considered to be a case of pure amnesia?

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Preview of the front of card 5
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