Pricipals of episodic retrieval

Question 1

event remembering

Answer 1

• cortical reinstatement
• sensory input goes to hippocampus which projects to regions
• sensory input is integrated in hippocampus

Question 2

Retrieval

Answer 2

• retrieval cue goes to sensory region to the hippocampus

- some of same hippocampal regions active during retrieval

Question 3

pattern retrieval

Answer 3

-stimulus during retrieval will activate others due to weighted connections

Question 4

cortical reinstatment

Answer 4

-hippocampus projects back to cortical regions (same regions that were activated during learning)

Question 5

Remembering as recapitulation

Answer 5

• patterns of activation are reinstated:
• reactivation of cortical patterns present in coding
• depends on establishment of cortical pattern at encoding
• hippocampal activation

Question 6

Human neuroimaging studies about episodic retrieval

Answer 6

• Remembering percepts

- remembering thoughts

Question 7

reinstatement

Answer 7

-reactivation of cortical patterns that were present during encoding

Question 8

• Remembering percepts paradigm

- Wheeler, 2000

Answer 8

Encoding
   -visual word + picture
   -visual word + sound
Retrieval 
   -presented visual word
   -remember if picture or sound 
-measure in scanner

Question 9

Remembering percepts results

Answer 9

• visual cortex active when perceiving and retrieving picture
• primary auditory cortex active when perceiving/retrieving sound
• retrieval activity less than perceive activity
• double dissociation

Question 10

Remembering thoughts

Answer 10

• present visual word (and think of a person or place to go with it)
• test: present word and remember what you imagined
• areas active for imagining a person or scene (specifically) were also active during retrieval or a person or scene

Question 11

Quantifying strength of cortical reinstatement

Answer 11

• training pattern
• build classifier for trials
• figure out what separates scene trials from people trials
• test classifier
• see if classifier can predict what they were imagining
• test on retrieal data
• can get numerical probability of whether the person was imagining a face or a scene
• classifier about 82% accurate
• as reinstatement strength increases, classifier becomes more accurate

Question 12

Does cortical reinstatement covary with hippocampus activity

Answer 12

• measured hippocampal activity during retrieval
• as hippocampal activity increased:
  
  • more likely to be a correct retrieval
  • faster reaction time
  • more reinstatement strength

Question 13

Relation between cortical reinstatement and cortical encoding pattern

Answer 13

• as encoding strength increases:
  
  • increased correct retrieval
  • decreased response time
  • increased reinstatement

Question 14

Role of MTL in associative memory and reinstatement (monkey study)

Answer 14

• found certain neurons responded to certain learned images
• learn pairs (optimal and associate)
• presented one cue and monkey has to find pair
• measure activity
• neuron fires for:
  
  • optimal cue
  • associated cue (no activity before the monkey had learned the pair, but now there is activity)

Question 15

pair-coding neuron

Answer 15

codes for pair of stimuli

Question 16

lesioning the perirhinal cortex and entorhinal cortex in monkeys
-what does this indicate about the role of the MTL?

Answer 16

• eliminated learned associative response
• moneys performed worse right after lesion
• the MTL is important for forming these associations

Question 17

Measuring TE and Perirhinal neurons during associative memory

Answer 17

• TE neuron: delayed response to associate cue
• memory needs to be retrieved from MTL (perirhinal)
• [associate cue causes optimal neuron to fire during delay to prepare for retrieval for (what it expects will happen next, which is) the optimal cue]