memoria in creier Flashcards
What is memory?
The mental function of retaining information about stimuli, events, images, ideas, etc. after the original stimuli is no longer present.
What is the structure of memory? (William James, 1890).
- Primary Memory (STM)
- Secondary Memory (LTM)
What is STM?
- Information in an active state.
- Conscious memory for what we are thinking about now.
What is LTM?
- Information in an inactive state
- Unconscious store of information
How has memory developed over the years after William James?
STM:
- Sensory memory
- Working memory
LTM:
- Declarative (explicit): facts, events
- Non-declarative (implicit): skills, priming
How do we know about the structure of memory?
Patients with brain damage have contributed to our understanding of how memory is structured.
What patients have we studied?
Those with amnesia.
What is amnesia?
Loss of memory ability
2 types:
1. Retrograde amnesia: loss of memory of events prior to damage.
2. Anterograde amnesia: loss of ability to form new memories
What are some causes of amensia?
Concussion
Migraine
Epilepsy
Surgery
Korsakoff’s syndrome
Ischemic events (restriction of blood supply e.g. stroke)
What is the evidence from amnesic patient Clive Wearing?
STM is spared
LTM is impaired
What is some evidence from Clive Wearing?
He had severe retrograde and anterograde amnesia.
He suffered frontal and temporal lobe damage, especially of the hippocampus.
He remembers little about his life (retrograde)
Each time he sees his wife it’s like it’s the first time (anterograde_
What is declarative (explicit) memory?
Conscious access and recall. (events and facts) e.g. your graduation.
What is non-declarative (implicit) memory?
No conscious access and recall e.g. riding a bike
What is the evidence from amnesic patient HM?
Declarative memory impaired
Non-declarative memory spared
What is the back story of HM?
HM had chronic epilepsy
To treat: bilaterally severed the hippocampus (removal)
This lead to profound memory impairments
What were the symptoms of HM?
LTM problems:
- retrograde amnesia for some events before surgery
- severe anterograde amnesia (failure to form new memories)
STM is relatively spared
- he performed well on digit-span tasks
What was HM symptoms in declarative vs non-declarative memory?
He could NOT learn meaning of new words (declarative)
He could learn a new skill (non-declarative)
What is hebbian learning?
The neural basis of information storage in the brain.
What is the concept of cells that fire together wire together?
When activation of neurone A causes activation of neurone B, the connection strength between A and B is increased.
What is long-term potentiation?
Long-lasting increase in efficiency of synaptic transmission.
1. Neuron A releases neurotransmitter into synaptic cleft
2. Neuron B has receptors to accept the neurotransmitters and generate an electric impulse
3. When neurone A and B fire simultaneously - this increases the no. of receptors at neurone B, which increases the likelihood that neurone A will fire.
Where does LTP occur?
In the hippocampus - evidence from taxi drivers
What is the role of prefrontal cortex in memory?
PFC engages representations of the meaningful contexts in which related memories occur.
What is the role of the hippocampus?
Forms and replays memories
