MVC - Memory III

Question 1

How does sensitization relate to synaptic plasticity? (Short-term vs Long-term)

Answer 1

Sensitization is a form of synaptic plasticity where the strength of a synapse increases. It can be:

• Short-term sensitization: Caused by changes in presynaptic release of neurotransmitters (glutamate in sensory neurons).
• Long-term sensitization: Involves changes in gene expression and protein production, leading to altered synapse structure and function.

Question 2

What is an engram, and how does it relate to memory?

Answer 2

An engram is a theoretical neural network or group of neurons that represent a specific memory

• It’s the physical basis for storing and retrieving memories

Question 3

What are the characteristics of engram cells? (3)

Answer 3

Engram cells are:

• Activated during learning experiences.
• Physically or chemically modified by learning.
• Reactivated when exposed to cues associated with the memory.

Question 4

How do engrams differ from memories?

Answer 4

Engrams are the foundation for memories but are not memories themselves. They provide the potential for a memory to exist, and retrieval cues are needed to activate the engram and form a conscious memory.

Question 5

How does contextual fear conditioning support the engram theory?

Answer 5

Studies in fear conditioning show that learning activates specific groups of neurons in the dentate gyrus, cortex, and amygdala. These activated neurons could potentially represent the engram for the fear memory.

Question 6

How can researchers manipulate engram cells? (2)

Answer 6

Studies have used CREB viral vectors to:

• Increase the likelihood of neurons becoming part of an engram.
• Selectively destroy neurons suspected to be part of an engram.

Question 7

What does the engram manipulation study in mice suggest about memory retrieval?

Answer 7

Ablating neurons thought to be part of a fear memory engram did not prevent memory retrieval.

• This suggests that memory retrieval might rely on reactivating a distributed network of neurons, not just a single engram

Question 8

How does Alzheimer’s disease affect memory?

Answer 8

Alzheimer’s disease disrupts memory formation and retrieval because it targets the entorhinal cortex and hippocampus, which are crucial for processing and storing new memories.