L20 - Learning and Memory

Question 1

What are the primary topics covered in the study of learning and memory?

Answer 1

Brain-damaged patient insights, memory types, storage and retrieval, hippocampus role, neural plasticity, and memory modulation.

Question 2

What was the significance of patient H.M. in memory research?

Answer 2

He had intact short-term memory but was unable to form new long-term memories after hippocampal tissue removal.

Question 3

What type of amnesia did patient H.M. have?

Answer 3

Anterograde amnesia, with impaired declarative memory but intact procedural memory and perceptual priming.

Question 4

How was patient N.A.’s amnesia caused?

Answer 4

By a brain injury that damaged the dorsomedial thalamus and mammillary nuclei.

Question 5

What is Korsakoff’s syndrome, and what causes it?

Answer 5

A memory disorder caused by thiamine deficiency, often due to alcoholism, resulting in confabulation and damage to mammillary bodies.

Question 6

What are the main stages of memory processing?

Answer 6

Encoding, consolidation, retrieval, and forgetting.

Question 7

What are the two major problems in memory research?

Answer 7

The systems problem (where memory is stored) and the molecular problem (mechanisms of storage).

Question 8

What is an engram?

Answer 8

A memory trace or the physical substrate of memory in the brain.

Question 9

What are the four criteria of an engram?

Answer 9

Persistence

ecphory (reactivation)

content-specificity

dormancy between encoding and retrieval.

Question 10

What is the role of the hippocampus in memory?

Answer 10

Essential for encoding and consolidating declarative memories.

Question 11

What is Hebbian theory?

Answer 11

The idea that “neurons that fire together, wire together,” strengthening synaptic connections through repeated activation.

Question 12

What is long-term potentiation (LTP)?

Answer 12

A long-lasting increase in synaptic strength following high-frequency stimulation.

Question 13

Where was LTP first discovered?

Answer 13

In the rabbit hippocampus at the CA3 to CA1 synapses.

Question 14

What is the first step in LTP?

Answer 14

Glutamate activates AMPA receptors, leading to depolarization and the removal of Mg²⁺ from NMDA receptors.

Question 15

What does Ca²⁺ influx during LTP trigger?

Answer 15

The insertion of more AMPA receptors into the postsynaptic membrane, enhancing sensitivity to glutamate.

Question 16

How does nitric oxide (NO) contribute to LTP?

Answer 16

NO diffuses back to the presynaptic cell, increasing glutamate release.

Question 17

What is the role of dopamine in LTP?

Answer 17

It tags synapses to make LTP relevant, activating pathways that increase gene expression for synaptic growth.

Question 18

How is LTP linked to memory and learning?

Answer 18

NMDA receptor function is critical for learning, and inhibiting protein synthesis blocks long-term memory consolidation.

Question 19

What are the temporal stages of LTP and long-term memory?

Answer 19

Short phase: Minutes.

Early phase: Hours.

Late phase: Hours to weeks (LTP) or a lifetime (LTM).

Question 20

Why is protein synthesis important for long-term memory?

Answer 20

It creates new synaptic components necessary for memory consolidation.

Question 21

What happens during memory retrieval?

Answer 21

Reactivation of engram neurons associated with the memory.

Question 22

What is the role of engram neurons in retrieval?

Answer 22

Silencing engram neurons disrupts retrieval without affecting new learning.

Question 23

Why do we forget?

Answer 23

Forgetting is adaptive, allowing the brain to discard outdated or irrelevant information and enhance psychological well-being.

Question 24

What is synaptic remodeling in forgetting?

Answer 24

The degradation of engram-specific synaptic connections over time.

Question 25

How does memory modulation affect memory retention?

Answer 25

Modulation involves changes in neural circuits that strengthen or weaken memories based on their relevance and emotional impact.

Question 26

How can memory decline with age?

Answer 26

Through reduced synaptic plasticity, decreased LTP efficiency, and loss of neuronal connections.

Question 27

What is the importance of studying memory systems and mechanisms?

Answer 27

To understand how memories are encoded, stored, retrieved, and forgotten, offering insights into cognitive disorders and therapies.