Memory Flashcards
What can long term memory be divided into?
Explicit memory and implicit memory
What can explicit memory be divided into?
Semantic memory and episodic memory
What is explicit memory?
Requires conscious recall
What is implicit memory?
Doesn’t require conscious recall
What is semantic memory?
Describes facts and general knowledge
What is episodic memory?
Describes personally experienced events
What are two types of implicit memory?
Procedural and priming
What is procedural memory?
Motor and cognitive skills we ‘remember’
What is priming?
Enhanced identification of objects or words (i.e. degraded information)
What is short term memory?
Short-term memory is the capacity for holding, but not manipulating, a small amount of information in mind in an active, readily available state for a short period of time
What is working memory (compared with STM)?
Not just to storage but also manipulation of STM contents.
How short is short term memory?
Very short, 5-18 seconds, decays rapidly
Why does STM decay?
Decays rapidly if material cannot be rehearsed such as by subvocal repetition - much easier when not multitasking.
How is STM memory tested?
Measure the span of STM
What are two branches of STM?
Verbal and visuospatial
Verbal span of STM tested by
Number of digits recalled (>9)
Visuospatial span of STM tested by
Corsi test - how many locations can you tap
Where is verbal STM stored?
Left parietal
Where is visuospatial STM stored?
Right hemisphere
What is a central feature of working memory?
Executive control mechanisms manipulate contents of STM
What areas are crucial for working memory?
Frontoparietal networks
Current anatomical model of working memory?
Parietal cortex maintenance / storage (slave systems)
(BUT now clear that even early sensory areas may play some role in STM storage)
Prefrontal cortex manipulation & monitoring information in STM
What improves STM?
Development and maturation of frontoparietal networks
What happens to STM and LTM with age?
Declines
What did patient HM show?
Bilateral medial temporal lesions involving the hippocampus show severe deficits in long-term memory (LTM) but intact STM capacity
Severe anterograde amnesia, recent retrograde amnesia
What does Ribot’s law state?
Old memories are more resistant to disruption or loss than new ones.
Temporal gradient in retrograde amnesia (First in, last out: earliest memories survive best)
What causes Korsakoff’s syndrome?
Severe thiamine deficiency
How does memory consolidation occur over time?
Initially hippocampal-cortical but eventually transfers to cortex.
So lesions of hippocampus won’t erase old memories which are consolidated and robustly represented in the cortex.
What do primacy and recency effects mean?
We remember more from the beginning and end of a list
Why is primacy and recency clinically relevant?
Patients recall best the information you give them at the beginning and end of the consultation.
How can recency be lost?
Filled delay after list (i.e counting backwards from 30 in 3s)
Why does a period of distraction (filled delay) reduce recency effect?
Prevents rehearsal and retention of words in STM.
Recency effect is thought to be mediated by…
STM
Amnesic patients show…
Intact recency but impaired primacy
Primacy effect may be mediated by
LTM
What is implied by the constructive nature of memory?
We reconstruct the past, sometimes based on previous knowledge, not always based on STM.
Why is memory constructive?
Remembering is an imaginative reconstruction built out of past reactions or experience and a little outstanding detail.
Memories can be modified or even created by the power of suggestion using misleading post-event information
What is confabulation?
False memories without conscious knowledge of their falsehood.
What is a likely cause of confabulation?
After orbitofrontal cortex damage and in Korsakoff’s syndrome
How does loss of semantic memory occur?
Shrinkage/ loss of left temporal pole (speech area)
