8. Memory Flashcards
What are the two major types of memory?
Short term memory (working memory) and long term memory
Short-term memory
Keeps information while you are working on it. Without active processing, the information will be lost quickly
Long-term memory
More enduring storage of information. Includes declarative and non-declarative memory
Declarative memory
Explicit – involves facts and events
Affected by the medial temporal lobe and diencephalon
You can explicitly remember these memories
Somantic memory
Involves remembering facts
Episodic memory
Involves remembering events
What are the major brain structures relevant to declarative memory?
Medial temporal lobe and diencephalon (thalamus and hypothalamus
Non-declarative memory
Implicit
You cannot tell exactly what it is that you have learned, but change in your task performance shows you did acquire memories of some sort. E.g. motor skills.
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What are the major brain structures relevant to non-declarative memory?
Straitum and cerebellum
What is remembered in long-term memory?
Procedural (skills and habits)
Priming
Simple classical conditioning
Non-associative learning
What brain structure affects procedural non-declarative memory?
Striatum
What brain structure affects priming non-declarative memory?
Neocortex
What brain structure affects simply classical conditioning in non-declarative memory?
Involves:
Emotional responses – Amygdala
Skeletal musculature – cerebellum
What brain structure affects non-associative learning in non-declarative memory?
Reflex pathways
What did Patient KC demonstrate?
He had diffused brain damage due to a motor cycle accident. Had general knowledge (i.e. semantic memory) was intact, but he lost his episodic memory.
This is a very unique case of amnesia
Amnesia
Pathological loss of memory
What is Amnesia caused by?
Head trauma Brain surgery (e.g. temporal lobectomy) Chronic alchoholism (e.g. Korsakoff’s syndrome) Brain infections (e.g. encephalitis) Ischemia (lack of blood flow) Hypoxia (lack of oxygen)
Retrograde amnesia
Loss of memory for events that occurred before the injury
Anterograde amnesia
Inability to learn new things
What did Patient HM demonstrate?
Received bilateral medial temporal lobectomy (as treatment for severe epilepsy)
Became densely amnesic as a consequence.
As a consequence HM suffers from MTL amnesia
What have scientists discovered by studying patients like HM?
The distinction between long-term and short-term memory
The distinction between declarative and non-declarative memory
The role of MTL in long-term declarative memory
What are the characteristics of a person with MTL amnesia?
After surgery, patient HM experienced: - life long anterograde amnesia - Some retrograde amnesia - but no loss of: o Remote (i.e. old memories) o short-term memory o non-declarative memory
What is the role of the MTL in long-term declarative memory?
Remote memories are dependent on the MTL
Remote memories are stored somewhere outside the MTL (memory consolidation)
What are the three distinct characteristics of the MTL in relation long-term declarative memory?
- MTL is important for forming new long-term memories
- Newly formed memories are dependent on the MTL
- MTL is not a permanent storage site for long-term memories
Where in the brain are long-term declarative memories stored more permanently?
Somewhere in the cortex. In particular, cortical areas that were used to perceive to-be-learned information
What did Wheeler et al. (2000) study in relation to memory consolidation?
Participants learned word-picture and word-sound pairs
In a recall test, only words were presented and participants indicated whether each word was accompanied with a picture or sound
What happens to sensory cortices during memory retrieval?
They were selectively activated. I.e. when there is a picture memory, the visual area of the brain is activated and when there is a sound memory there is an activation of the auditory area
Once a memory is consolidated, is it a done-deal?
When a long-term memory is retrieved, it goes back into an unstable (liable state). Thus, it has to be consolidated again (reconsolidated). This opens up the possibilities for memory manipulation
What are examples of Non-MTL amnesia?
Diencephalic amnesia – e.g. Korsakoff’s syndrome
What is Korsaoff’s syndrome?
Damage medial portions of the thalamus and hypothalamus
What happened to patient NA (Teuber et al., 1968)?
He incurred injury to the mammillary bodies (part of the hypothalamus)
What is still unclear in relation to memory and brain structures?
It is still unclear as to how the brain structures mentioned contribute to long-term declarative memory
What are some examples of the brain areas involved in non-declarative memory?
There are many forms of non-declarative memory, so many brain areas are involved in them including:
- the cerebellum: sensorimotor skills
- Striatum: stimulus-response associations
Straitum
Important for learning and retrieving specific response that are to be made in response to specific stimuli.
What are the two strategies for spatial navigation?
Place strategy and response strategy
Place strategy in spatial navigation
Identify object locations within a larger environmental framework
Rapidly acquired, allows flexible behaviour (e.g. short-cut), but requires conscious retrieval and susceptible to forgetting
Similar to declarative memory
Response strategy in spatial navigation
Perform a specific sequence of action
Slow to learn, only rigid behaviour is possible, but does not require conscious awareness and much-longer-lasting
Similar to non-declarative memory
How can we manipulate navigation strategies in animals?
By selectively lesioning the MTL and caudate nucleus.
MTL is important for place strategy (declarative memory)
Cadate is important for response strategy (non-declarative memory)
Hebbian theory
Neurons fire together, wire together
After repeated stimulation, synaptic transmission becomes more efficient
Hebb (1949) argued that this change is the basis of long-term memory
Long-term potentiation
Long-lasting facilitation of synaptic transmission
What is the rate of growth in LTP similar to?
The rate of growth in LTP is similar to the rate of behavioural improvement by learning
How can LTP be produced?
LTP can be produced within seconds and long-term declarative memory can be learned quickly too
How can LTP be produced?
They can both last for weeks (and longer)
