Memory (Part 3) Long Term Memory Flashcards Preview

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Flashcards in Memory (Part 3) Long Term Memory Deck (22):
1

Long-term Memory

Long-term memory is available for longer durations and can be retrieved at later stages in peoples’ lives

Long-term memory is not just one big store, but it is composed of multiple systems

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Long-term memory
Declarative (explicit) memory

what? why? when? where? who?
knowledge, facts, locations
conscious access
hippocampus-dependent

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Long-term memory
Non-declarative (implicit) memory

how?
motor skills, cognitive skills
unconscious access
not hippocampus-dependent

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Declarative memory (semantic)

what, why?
General knowledge of facts about the world
Absence of the specific circumstances of when the knowledge was acquired

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Declarative memory (episodic)

when, where
knowledge of events, including our own lives
autobiographical memory

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The several systems of long-term memory (implicit)

Implicit LTM can also be divided into several different memory systems

They have in common that we do not have a conscious recollection of how we learned – but we just get better with experience and practice!

procedural
priming
classical conditioning
non associative

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Procedural memory

Procedural memory is our memory for skills

motor skills
cognitive skills
- e.g. drawing, sports
- e.g. learning to speak (first years)


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Priming

Priming refers to forming automatic associations

Change in ability to identify stimulus as result of prior exposure

Repetition priming: e.g. prior exposure to word in lexical decision task

Associative/semantic priming: related word: e.g. “nurse” primes “doctor”

Priming occurs masked and unmasked

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Classical Conditioning

associative learning
attend to neutral stimulus after association with meaningful stimulus

a new stimulus when paired with an unconditioned stimulus over many trials produces a conditioned response all on its own

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Non-associative
(habituation and sensitisation)

Habituation: ignore a stimulus because it is trivial
e.g. background noise

Sensitisation: attend to a potentially threatening stimulus
e.g. snakes

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Proactive interference:

prior (old) learning interferes with new learning
e.g. friend’s maiden name interferes with new name

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Retroactive interference:

more recently learned information (new) interferes with previous learning (old)
e.g. new phone number interferes with remembering old phone number

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Amnesia

Amnesia refers to deficits in memory caused by brain damage, disease, drug abuse, or psychological trauma

One can distinguish between two types of amnesia

Patients suffering from amnesia can show very selective memory deficits. This can provide support for Dissociations between memory systems:
between short-term and long-term memory
between declarative and non-declarative memory
between semantic and episodic systems

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Retrograde amnesia

is the inability to remember knowledge acquired before the brain injury

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Anterograde amnesia

The inability to remember anything since the brain injury
The inability to acquire new knowledge (impedes learning)

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H.M case study

Severe case of epilepsy for years

Removal of the medial portion of both temporal lobes, including the hippocampi in 1953

Died in 2008, best studied patient in history (e.g. Scoville & Milner, 1957)

Normal sensory memory, normal working memory, normal digit span

He could not recall events of his life up to a year prior to the surgery

He could not learn new knowledge

However, he could learn the mirror tracing task

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H.M
Which memory systems were damaged?
Which memory systems were intact?

damaged:
He suffered from a temporally-graded retrograde amnesia

He also suffered from anterograde amnesia

This reflects an interruption of the consolidation process

This was interesting because it demonstrated that the hippocampi are involved in memory consolidation and transfer of memories to LTM

intact:
His procedural memory was intact

Implicit memory does not seem to be affected by loss of hippocampi

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Clive Wearing

He was a professional broadcaster and musician

He had herpes encephalitis that damaged his brain (swelling and bilateral hippocampus damage)

The recall of autobiographic details was poor

The capacity to learn new things was poor

His general knowledge prior to accident was good

His musical ability were preserved




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What we can deduce from Clive's case

Clive suffered from retrograde amnesia

The association cortex (temporal, parietal) is important for storage of memory

He suffered from a loss of declarative memory (same for Alzheimer’s disease)

Episodic memory appears to be more fragile than semantic memory

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Graf, Squire, & Mandler (1984): Experiment

A group of anterograde amnestic patients studied a list of word pairs, followed by a delay period

They then performed 4 different tasks to test the nature of the memory impairments. These tasks differed in the extent to which they required a conscious effort to retrieve information

- free recall (list as many words as you remember)
- recognition (do you recognise this word?)
- cued recall (was this word on the list?)
- word-stem completion (when presented with three initial letters, complete with the first word that comes to mind)

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Graf, Squire, & Mandler (1984): Experiment: Results

Patients anterograde amnesia were only good at word-stem completion, but bad at the other tasks

They showed a strong bias to use studied items to complete the word stem – although they could not recall the words or consciously remember the encoding at all

This is experimental evidence that implicit memory is intact in these patients! The word-stem completion task is an example of repetition priming

These (and many more) case studies and experiments with patient groups demonstrate that memory is a complex combination of systems with different neural substrate rather than one unified store

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Alcohol induced amnesia

Alcohol can cause anterograde amnesia for events experienced under the influence of the drug (alcoholic “blackout”)

It also has a curious effect of “retroactive enhancement” for memories encoded just prior to the consumption of alcohol

Alcohol might “close” the hippocampus to new inputs, no consolidation of previously learned information can take place

Long-term damage is described as the “Korsakoff’s Syndrome” – profound and permanent anterograde and retrograde amnesia