Week 8 Flashcards
Who invented the term “engram” and what does it mean?
- Richard Semon
- A sustained neural representation of behavioural experience
What are the 4 properties of an engram?
- Persistent
- Ecphory (retrieval)
- Dormant
- Content
What does it mean for an engram to have the potential for ecphory?
An engram may be expressed behaviourally through interactions with retrieval cues
Hebb believed that modified _____ are the basis of memory
modified connections among neurons belonging to cell assemblies
What is the modern term for “cell assemblies”
Neuronal ensembles
What method did researchers use to search for engrams?
Lesion techniques
What activates the expression of intermediate early genes?
The rise of intracellular calcium and other second messengers
What can IEGs be used for?
To mark a neuron that was activated by a behavioural experience
How long do IEG markers endure?
A few minutes
How does the IEG arc work?
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
What was the TetTag mouse?
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
The TetTag mouse was genetically engineered so that Fos promotes _____
the expression of the tTA system instead of c-Fos, which promotes the expression of LAC
The ability to study the functional properties of neurons changed dramatically with _____
The development of optogenetics, and the ability to combine it with cell-tagging systems
What allows an engram to persist through the post-learning period?
Repetitive synchronous subensemble activity
What type of neuron is preferred for fear engrams, and why?
Virally infected neurons overexpressing CREB, because they are more excitable
The engram is the ____ basis for a ____
- physical
- memory
What do excitotoxins do?
Excite the neuron so much that it dies
What do glutamatergic agonists do?
Damage the connections between neurons rather than the neuron itself
Lashey found that ____ was more important than ____ in affecting maze performance in rats
- the amount of damage
- the location of the damage
To conclude that neurons belong to an engram, a researcher must ______
- 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
Immediate early genes are expressed when ____
A neuron depolarizes
In a TetTag mouse, a neuron can be considered to be part of an engram if _____
It contains both LAC and ZIF
Neurons in the ____ compete to be part of the neural ensemble that supports a feat memory, and ______ win the competition
- lateral amygdala
- neurons expressing high levels of CREB at the time of fear conditioning
What are the limitations of neuroimaging?
Different brain regions will light up depending on the task, other than those involved in the engram
