Chapter 12 Flashcards
(43 cards)
Lashley’s research
- searched for the physical representation of learned material (endogram)
- cut brains of rats to interrupt connections and let them go through a maze (not successful)
- proposed: equipotentiality and mass action
- unnecessary assumptions: engrams are in cerebral cortex and all kind of learning are basically the same
lateral interpositus nucleus (LIP)
Thomson
- crucial for learning
- research with rabbits: cooled or drugged LIP does not send signals -> no learned CS
BUT: when LIP recovered from impact, learning was possible
Thomson research brain regions
- research on learning/CC with rabbits
- lateral interpositus nucleus (LIP)
- red nucleus
Red nucleus
- midbrain motor area
-receives input from cerebellum
-Thomson research: if suppressed, rabbits showed no reaction of learning CS BUT when recovered, they have been better than before
-> Prevented response, but not learning
-> Cerebellum plays important role in learning !
but also different brain areas (ex.learning tastes in the amygdala)
Distinction long-term (LTM) & short-term memory (STM)
- Hebb: distinguished LTM and STM, when we hold an information long in the STM it consolidates into LTM
- > critic: information does not have to be stored in LTM even after rehearsing it for an hour
Why can emotionally information be remembered more quickly?
- excitement = secretion of epinephrine and cortisol
- Cortisol activates amygdala and hippocampus
=> amygdala and hippocampus enhance storage and consolidation of recent experiences - Amygdala stimulates the hippocampus and cerebral cortex (both important for memory storage)
- stress (more cortisol) impairs memory, impact: consolidation can be faster or slower
Working memory
- the way we store information while we are working with them
- common test :delayed response tasks =reacting to a stimulus delayed
- Prefrontal cortex is crucial for this storage
- during delay: cells in prefrontal cortex and parietal cortex increase activity
- old people with declining memory show decline in activity in the prefrontal cortex
- old people with intact memory show greater activity in prefrontal cortex than young people
- > Maybe prefrontal cortex has to work harder to compensate for impairments elsewhere in the brain
brain areas involved in memory
- hippocampus
- amygdala
- prefrontal cortex
- basal ganglia (to some degree)
patient HM
- got hippocampus removed
- No LTM, but WM
- form a few weak semantic memories
- severe impairment of episodic memory
- strong retrograde amnesia for episodic memory (knows information, but not where he got them from)
- retrograde as well as anterograde amnesia
anterograde amnesia
- inability to form memories for events that happened after brain damage
retrograde amnesia
loss of memory for events that occurred before the brain damage
Both: retrograde and anterograde amnesia
- damage to hippocampus and surrounding medial temporal lobe
- retrograde is most sever for the time (couple of years) just before the damage -> usually remember childhood etc.
recalling past / imagine future
- same brain areas active for both activities, incl. hippocampus
- > in anterograde amnesia: as impaired in imagine the future as they are in recalling the past
implicit memory and amnesia
- patients with amnesia have better implicit memory than explicit/ declarative memory (experiment: friendly, unfriendly, neutral people)
- ## also procedrual memory (form of implicit memory) is intact even if the patient is not aware of his skills.
Hippocampus and Declarative Memory
- Although patients with hippocampal damage acquire new skills, they have great trouble learning new facts
- > Hippocampus related to declarative and episodic memory
delayed matching-to-sample task
animal sees an object (the sample) ,after a delay,gets a choice between two objects, from which it must choose the one that matches the sample.
delayed nonmatching-to-sample task
animal sees an object (the sample) ,after a delay,gets a choice between two objects, from which it must choose the one that is different from the sample
spatial memory
- hippocampus is involved in spatial memory,
- > taxi drivers have been found to have greater activation in hippocampus when ask for the shortest way
- > They also had bigger posterior hippocampus => Actual growth of adult human hippocampus in response to spatial learning experiences
contextual memory
- hippocampus is important for contextual memory:
- > coordinator to create episodic memory, director of all experiences (sound, colour, series of events)
- > reconstructs the context!
brain activity episodic memory
episodic memory: activity in and around hippocampus synchronize with several parts of the cortex
=> consistent with the idea of the hippocampus as providing the connections
people remember better with …
... flashcards. and context (environment ) and detail for STM. This is less important for LTM.
When time pass by…
- memories are not as detailed and lose context.
- > activity in the cortex is greater and in hippocampus becomes less
Korsakoff’s syndrome/ Wernicke-Korsakoff syndrome
- Often in alcoholics
- caused by prolonged thiamine (vitamin B1) deficiency
- > Thiamine important to metabolize glucose
- > Thiamine deficiency leads to loss or shrinkage of neurons throughout the brain
- dorsomedial thalamus is mostly affected => main source of input to the prefrontal cortex
- Similar symptoms like patients with prefrontal cortex damage: Apathy, confusion, memory loss
- Overlapping symptoms with hippocampal damage: impairment of episodic memory, but spared implicit memory
- Confabulation
Confabulation
- Filling memory gaps with guesses
- Not about semantic questions or nonsense questions, mainly about episodic questions
- Most answers are more pleasant than the actual present
- Try to act according to their confabulations