Modern questions in learning and memory

Question 1

What do kenyon cells receive input from?

Answer 1

Multiple projection neurons

Question 2

What do Kenyon cells require to fire?

Answer 2

multiple simultaneous inputs

Question 3

What do 3rd order neurons do?

Answer 3

Sample 2nd order neurons to respond selectively to odours

Question 4

How much of the coding space are Kenyon cells sampling?

Answer 4

Very small part

Question 5

What happens when a fly receives reward or punishment?

Answer 5

1. Activation of dopaminergic neurons
2. Co-activation of odor specific subset of kenyon cells
3. synaptic plasticity at the output synapses of the kenyon cells activated

Question 6

What do changes in olfactory associative memory lead to?>

Answer 6

Changes in behaviour

Question 7

What can overlapping and subsequent activation of Kenyon cells lead to?

Answer 7

If an odour and a particular subset of Kenyon cells are associated with a bad odour and a new odour overlaps with some of these cells it can also lead to avoidance

Question 8

What does the Gal4/UAS system allow us to do?

Answer 8

Artificially express arbitrary transgenes in specific cells

Question 9

How does Gal 4 work?

Answer 9

Bind to UAS (upstream activating system)
Recruits RNA polymerase
Induces the transcription of anything following UAS
Can combine Gal4 and UAS to transcribe any gene you want

Question 10

What does the split Gal 4 system allow?

Answer 10

Greater specificity

Question 11

What is the mushroom body made up of?

Answer 11

Kenyon cells

Question 12

What is it innervated by?

Answer 12

Dopaminergic neurons (dont overlap)

Question 13

What is there 1:1 matching between?

Answer 13

Dopaminergic neurons and output neurons

Question 14

In Kenyon cells what does stimulation of a reward neuron lead to? (approach or avoid)

Answer 14

Stimulation of reward leads to a WEAKENING of the avoidance behaviour

Question 15

What happens if you shock a fly before an odour? (what behaviour does this lead to?)

Answer 15

Approach behaviour because the odour marks the end of the negative stimulus

Question 16

So from above, how can stimulation of the same of dopaminergic neurons lead to different responses?

Answer 16

2 types of dopamine receptor

Question 17

What do you potentiate if a reward comes right before an odour?

Answer 17

the avoidance neuron

Question 18

What happens if you reward comes right after or overlaps odour?

Answer 18

you depress and behaviour becomes a conditioned approach

Question 19

What type of G protein is the dDA1 dopamine receptor? (DopR1)

Answer 19

Gs

Question 20

What pathway does the dDA1 receptor represent?

Answer 20

Aquisition

Question 21

What type of G protein is the Damb receptor? (DopR2)

Answer 21

Gq

Question 22

What pathway is the DopR2 receptor involved in?

Answer 22

forgetting

Question 23

Which pathway therefore is important for potentiating the synapse and which for depressing? (think its not that obvious)

Answer 23

Acquisition pathway important for depressing and vice versa

Question 24

What is the analogy to the cerebellum?

Answer 24

Projection neurons going onto kenyon cells = Mossy fibres going onto granule cells in the cerebellum forming parallel fibres which are intersected by purkinje cells

Question 25

What are synapses between the granule cells and the Pukinje cells depressed by?

Answer 25

Climbing fibres

Question 26

What do climbing fibres carry?

Answer 26

messages that say you have made a mistake (depression)

Question 27

What drives motor learning?

Answer 27

LTD between granule cells and purkinje cells this drives motor leaning

Question 28

What is the problem that the electric fish has?

Answer 28

The electricity it produces is also picked up by its own cells

Question 29

How does error correction get around this problem for the electric fish?

Answer 29

1. Electric organ sends efferent copy
2. Granule cells active are cancelled out by matching efferent copy
3. by depressing synapse between granule cell and purkinje cell

Question 30

What is the difference between sensitisation and associative learning?

Answer 30

the same neurons are stimulated, but simultaneously in associative learning