Week 6: Long-Term Memory Flashcards
What are the two Types of Long-Term memory?
- declarative memory (explicit memory)
- non-declarative memory (implicit memory)
What are the two types of declarative memory?
- episodic memory
- semantic memory
What kind of memories are part of the episodic memory?
specific personal experiences from a particular time and place (events)
What kind of memories are part of the semantic memory?
- world knowledge
- object knowledge
- language knowledge
- conceptual priming
(Facts)
What is part of the nondeclarative memory?
- procedural memory
- perceptual representation system
- classical conditioning
- nonassociative learning
What is stored in the procedural memory?
Skills (motor and cognitive)
What is nonassociative learning?
Habituation, Sensitization
What is classical conditioning?
Conditioned responses between two stimuli
What does the perceptual representation system do?
Perceptual Priming
What is Ribot‘s Law in the context of Amnesia?
- time gradient in retrograde amnesia
- more recent memories are more vulnerable to be forgotten in case of a brain injury
→ evidence for „fragile“ consolidation stage
What impact do concussions have on memory (football player study)
- Football players with concussions could recall events just before injury well, when interviewed immediately after injury
- 3-20 min later the recall was lost → information is „there“ but does not get stored in LTM
- delayed forgetting was not observed in players with other injuries
Who is patient H.M.?
- famous patient
- very frequent and severe epileptic seizures
- half of hippocampus and 5cm of medial temporal lobe surgically removed
- atrophy of remaining hippocampus (prob. Due to loss of surrounding input)
What were H.M.‘s symptoms after the surgery?
- near normal intelligence (wechsler IQ)
- normal perception
- normal STM (digit span), unless distracted
- normal skill learning (mirror-tracing task) and priming
- anterograde loss of declarative LTM (e.g. location of rooms, names of associates, way to the toilet, etc. )
- minor retrograde loss of declarative memory (intact up to 2 years before surgery → consolidation)
- low scores on verbal paired associate learning
What are the Conclusions of Patient H.M.?
- Hippocampus not a site where LTM is stored
- Hippocampus not site of STM
- Hippocampus = site of Consolidation, where STM is transformed to LTM?
In what stages of memory does the MTL play a role in LTM?
- Encoding
- Consolidation
- Retrieval
How does the MTL play a role in the Encoding stage of LTM?
- Input encoded in sensory systems
- hippocampus stores „pointers“ to these representations
How does the MTL play a role in the Consolidation stage of the LTM?
- strengthening of some representations through re-activation
- slow transfer of memory representations to cortex
- over time, memory representation independent of hippocampus
How does the MTL play a role in the Retrieval stage of the LTM?
- relevant for both retrieval of non-consolidated and consolidated memory
- triggered by retrieval-cue
- via hippocampus (recent) or by cortical association (remote memories)
What is LTM Consolidation?
- memories that were encoded in the hippocampal region are moved to the neocortex for more permanent process
- is a dynamic process: representations are constantly updated to incorporate new memories
What is Reconsolidation?
Memory traces of previously consolidated memories are activated
What are Place Cells?
- „you are here“ cells
- part of the hippocampus
What are Grid Cells?
- like a ruler → keeping track of how far you are going
- in entorhinal cortex
- pattern in a bigger environment: an even grid
- not a Cartesian system, but hexagonal
What are border cells?
help with navigating relative to objects in the environment
What could the role of MTL in LTM explain?
- Why MTL damage causes anterograde and limited retrograde amnesia
- Ribot‘s law (temporal gradient of retrograde amnesia)
- Lesions in MTL, but not cortex, cause severe amnesia
- MTL lesions cause global amnesia (cortical lesions can cause modality specific amnesias)
What is the place field?
- Similar to a visual receptive field
- not in the visual field, but in the world
what is sleep consolidation and playback?
- MTL cells exposed to the place fields have higher firing rate during subsequent sleep periods
→ could be a mechanism of consolidation for transfer of memory to neocortex while neocortex is not busy processing external stimuli
What are the different stages of memory?
Encoding
Consolidation
Storage
Retrieval
What is the MTL ?
The Medial Temporal Lobe
Includes:
- amygdala
- peririhnal Cortex
- Entorhinal Cortex
- Hippocampus
- Parahippocampal Cortex
