Week 8

Question 1

Who invented the term “engram” and what does it mean?

Answer 1

• Richard Semon

- A sustained neural representation of behavioural experience

Question 2

What are the 4 properties of an engram?

Answer 2

• Persistent
• Ecphory (retrieval)
• Dormant
• Content

Question 3

What does it mean for an engram to have the potential for ecphory?

Answer 3

An engram may be expressed behaviourally through interactions with retrieval cues

Question 4

Hebb believed that modified _____ are the basis of memory

Answer 4

modified connections among neurons belonging to cell assemblies

Question 5

What is the modern term for “cell assemblies”

Answer 5

Neuronal ensembles

Question 6

What method did researchers use to search for engrams?

Answer 6

Lesion techniques

Question 7

What activates the expression of intermediate early genes?

Answer 7

The rise of intracellular calcium and other second messengers

Question 8

What can IEGs be used for?

Answer 8

To mark a neuron that was activated by a behavioural experience

Question 9

How long do IEG markers endure?

Answer 9

A few minutes

Question 10

How does the IEG arc work?

Answer 10

Translocates to the cytoplasm when transcribed in the nucleus, so arc will be present in both the cytoplasm and nucleus of neurons activated by an experience

Question 11

What was the TetTag mouse?

Answer 11

It was genetically engineered so that it could tag a recently activated neuron with a reporter gene tau-LAC, which can endure for several days

Question 12

The TetTag mouse was genetically engineered so that Fos promotes _____

Answer 12

the expression of the tTA system instead of c-Fos, which promotes the expression of LAC

Question 13

The ability to study the functional properties of neurons changed dramatically with _____

Answer 13

The development of optogenetics, and the ability to combine it with cell-tagging systems

Question 14

What allows an engram to persist through the post-learning period?

Answer 14

Repetitive synchronous subensemble activity

Question 15

What type of neuron is preferred for fear engrams, and why?

Answer 15

Virally infected neurons overexpressing CREB, because they are more excitable

Question 16

The engram is the ____ basis for a ____

Answer 16

• physical

- memory

Question 17

What do excitotoxins do?

Answer 17

Excite the neuron so much that it dies

Question 18

What do glutamatergic agonists do?

Answer 18

Damage the connections between neurons rather than the neuron itself

Question 19

Lashey found that ____ was more important than ____ in affecting maze performance in rats

Answer 19

• the amount of damage

- the location of the damage

Question 20

To conclude that neurons belong to an engram, a researcher must ______

Answer 20

• be able to tag cells activated by the behavioural experience
• demonstrate that some of those cells are also activated by the memory test
• direct activation of these cells activates the appropriate behaviour
• inhibiting these cells prevents the occurrence of the appropriate behaviour

Question 21

Immediate early genes are expressed when ____

Answer 21

A neuron depolarizes

Question 22

In a TetTag mouse, a neuron can be considered to be part of an engram if _____

Answer 22

It contains both LAC and ZIF

Question 23

Neurons in the ____ compete to be part of the neural ensemble that supports a feat memory, and ______ win the competition

Answer 23

• lateral amygdala

- neurons expressing high levels of CREB at the time of fear conditioning

Question 24

What are the limitations of neuroimaging?

Answer 24

Different brain regions will light up depending on the task, other than those involved in the engram