L20 - Learning and Memory Flashcards
What are the primary topics covered in the study of learning and memory?
Brain-damaged patient insights, memory types, storage and retrieval, hippocampus role, neural plasticity, and memory modulation.
What was the significance of patient H.M. in memory research?
He had intact short-term memory but was unable to form new long-term memories after hippocampal tissue removal.
What type of amnesia did patient H.M. have?
Anterograde amnesia, with impaired declarative memory but intact procedural memory and perceptual priming.
How was patient N.A.’s amnesia caused?
By a brain injury that damaged the dorsomedial thalamus and mammillary nuclei.
What is Korsakoff’s syndrome, and what causes it?
A memory disorder caused by thiamine deficiency, often due to alcoholism, resulting in confabulation and damage to mammillary bodies.
What are the main stages of memory processing?
Encoding, consolidation, retrieval, and forgetting.
What are the two major problems in memory research?
The systems problem (where memory is stored) and the molecular problem (mechanisms of storage).
What is an engram?
A memory trace or the physical substrate of memory in the brain.
What are the four criteria of an engram?
Persistence
ecphory (reactivation)
content-specificity
dormancy between encoding and retrieval.
What is the role of the hippocampus in memory?
Essential for encoding and consolidating declarative memories.
What is Hebbian theory?
The idea that “neurons that fire together, wire together,” strengthening synaptic connections through repeated activation.
What is long-term potentiation (LTP)?
A long-lasting increase in synaptic strength following high-frequency stimulation.
Where was LTP first discovered?
In the rabbit hippocampus at the CA3 to CA1 synapses.
What is the first step in LTP?
Glutamate activates AMPA receptors, leading to depolarization and the removal of Mg²⁺ from NMDA receptors.
What does Ca²⁺ influx during LTP trigger?
The insertion of more AMPA receptors into the postsynaptic membrane, enhancing sensitivity to glutamate.
How does nitric oxide (NO) contribute to LTP?
NO diffuses back to the presynaptic cell, increasing glutamate release.
What is the role of dopamine in LTP?
It tags synapses to make LTP relevant, activating pathways that increase gene expression for synaptic growth.
How is LTP linked to memory and learning?
NMDA receptor function is critical for learning, and inhibiting protein synthesis blocks long-term memory consolidation.
What are the temporal stages of LTP and long-term memory?
Short phase: Minutes.
Early phase: Hours.
Late phase: Hours to weeks (LTP) or a lifetime (LTM).
Why is protein synthesis important for long-term memory?
It creates new synaptic components necessary for memory consolidation.
What happens during memory retrieval?
Reactivation of engram neurons associated with the memory.
What is the role of engram neurons in retrieval?
Silencing engram neurons disrupts retrieval without affecting new learning.
Why do we forget?
Forgetting is adaptive, allowing the brain to discard outdated or irrelevant information and enhance psychological well-being.
What is synaptic remodeling in forgetting?
The degradation of engram-specific synaptic connections over time.
