Episodic Memory

Question 1

1. Definition of episodic memory

Answer 1

Ability to remember a past event

 Allows us to re-experience the past, stay oriented in the present and plan for the future

Question 2

2. Binding problem in memory

Answer 2

To form a useful episodic memory, the specific aspects of an event need to be processed and bound together, to specify the spatiotemporal context of the memory

Question 3

3. BIC model

Answer 3

=Binding of items and context model (Diana, Yonelinas and Ranganath)

Anatomical organisation of the MTL
• Perirhinal cortex receives “what” information  specific items (who and what)
• Parahippocampal cortex receives “where” information  context (where and when)
• Both project to the entorhinal cortex, which in turn projects to the hippocampus, where “what” and “where” information come together

Question 4

4. Recollection and familiarity

Answer 4

Basic prediction of (among others) the BIC: recollection vs. familiarity
• Hippocampus supports recollection of contextual information, while perirhinal cortex alone might be sufficient for familiarity
• hippocampal lesions: far more problems with recollection than with familiarity
• fMRI: activity of hippocampus and parahippocampal cortex correlated with subsequent context recollection only, perirhinal cortex with familiarity only

Question 5

5. Criticism of the BIC model

Answer 5

Squire, Wixted and Clark: Differences in MTL activation could just reflect relative differences in sensitivity to strong vs. weak memories!
But: Falsified by a recent study, manipulating learning via item or context
• Participants learned an item-colour association: colour was either an item-feature or a context information
• When context information, memory was primarily supported by recollection, when item feature, familiarity played a role too
• Differential activation in fMRI in MTL subregions, consistent with earlier findings
•  Involvement of different MTL subregions relates to the kind of information retrieved

After hippocampal damage, memory for association between items is sometimes supported by extrahippocampal regions like perirhinal cortex
Potential answer: Two items can be processed as a larger, unitary configuration
• Unitizing word pairs (by providing a novel definition, e.g. “motorbear”) is related to increased perirhinal cortex activity during encoding and increased familiarity at test

Question 6

6. Relationship of episodic memory to conscious awareness and guidance of visual attention

Answer 6

MTL and consciousness
• BIC model postulates that MTL subregions support the recovery of information, but other regions may be required to integrate this to guide conscious behaviour
• Study with face-scene associations and eye-movements: Hippocampal activity correlated with viewing of the correct face, even when it was not correctly (consciously) identified
•  hippocampus provides a key ingredient for conscious recollection

Question 7

7. The role of PFC in episodic memory

Answer 7

Memory is selective, because it is based on our current goals
 PFC plays a role in selection, maintenance and organisation of goal-relevant information
 as well as in episodic memory encoding and retrieval

Differential involvement of PFC areas
• vlPFC: controls selection of the relevant features of items
o vlPFC activity is increased during successful memory formation
• dlPFC: related to processing of relationships between items
o dlPFC activity during encoding predicts subsequent memory especially if tasks involve relational processing
o Memorising word pairs: activity correlated with recognition of associations, but not with recollection of individual items