Memory (Part 3) Long Term Memory Flashcards
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
Long-term memory
Declarative (explicit) memory
what? why? when? where? who?
knowledge, facts, locations
conscious access
hippocampus-dependent
Long-term memory
Non-declarative (implicit) memory
how?
motor skills, cognitive skills
unconscious access
not hippocampus-dependent
Declarative memory (semantic)
what, why?
General knowledge of facts about the world
Absence of the specific circumstances of when the knowledge was acquired
Declarative memory (episodic)
when, where
knowledge of events, including our own lives
autobiographical memory
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
Procedural memory
Procedural memory is our memory for skills
motor skills
cognitive skills
- e.g. drawing, sports
- e.g. learning to speak (first years)
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
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
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
Proactive interference:
prior (old) learning interferes with new learning
e.g. friend’s maiden name interferes with new name
Retroactive interference:
more recently learned information (new) interferes with previous learning (old)
e.g. new phone number interferes with remembering old phone number
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
Retrograde amnesia
is the inability to remember knowledge acquired before the brain injury
Anterograde amnesia
The inability to remember anything since the brain injury
The inability to acquire new knowledge (impedes learning)
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
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
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
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
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)
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
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
