Learning and Memory

Question 1

What is learning?

Answer 1

Acquisition of information

Question 2

What is memory?

Answer 2

Storage of learned information

Question 3

What is recall?

Answer 3

Reacquisition of stored information

Question 4

What is the engram?

Answer 4

Physical embodiment of a memory i.e. the physical and chemical changes from storing a memory

Question 5

What are the main types of memory? (4)

Answer 5

• Procedural/declarative memory
• Implicit/explicit memory

Question 6

What is procedural memory?

Answer 6

Skills that are largely unavailable to conscious mind e.g. riding a bike

Question 7

What is declarative memory? (2)

Answer 7

• Factual information that is available to the conscious mind
• Can be encoded in symbols/language and transmitted between individuals

Question 8

What is explicit memory?

Answer 8

Memory that can be consciously recalled

Question 9

What is implicit memory?

Answer 9

Memory that can’t be consciously recalled

Question 10

What are the 3 types of implicit memory?

Answer 10

• Procedural memory
• Classical conditioning
• Priming

Question 11

What is priming?

Answer 11

When one stimulus influences the response to subsequent stimuli

Question 12

What are the advantages of using ‘simple’ systems to study memory? (5)

Answer 12

• Neuronal size (easy to record from)
• Circuit complexity
• Temperature dependence mutations
• Mapping tools (genetic manipulation)
• Fewer ethical issues

Question 13

What are the simple forms of memory? (2)

Answer 13

• Habituation
• Sensitisation

Question 14

What is habituation?

Answer 14

Decrease in the amplitude of the response as the stimulus is repeated

Question 15

What is sensitisation?

Answer 15

Increase in the amplitude of the response as the stimulus is repeated

Question 16

What are examples of habituation in humans? (4)

Answer 16

• Habituation of eye blink reflex
• Habituation of repetitive non-harmful stimulus presentation
• Habituation of visual attention
• Habituation of emotional response

Question 17

How can habituation be studied?

Answer 17

Gill withdrawal reflex in Aplysia

Question 18

What is habituation of the gill withdrawal reflex? (2)

Answer 18

• Touch of water jet causes gill withdrawal
• Repeating the stimulus reduces the reflex

Question 19

How does habituation happen in the gill withdrawal reflex? (2)

Answer 19

• Sensory neuron in the siphon skin forms a synapse with a motor neuron which connects to the gill muscle
• When the stimulus is repeated, the presynaptic sensory neuron response stays the same but the postsynaptic motor neuron response decreases = habituation

Question 20

What is the molecular mechanism of habituation?

Answer 20

Reduced neurotransmitter release due to depletion of the readily releasable pool (RRP) so the amplitude of each response gets smaller

Question 21

What is the readily releasable pool (RRP)?

Answer 21

The vesicles containing neurotransmitter that are in the active zone and are immediately released following depolarisation

Question 22

What is the proximal pool?

Answer 22

The vesicles containing neurotransmitter which diffuse to the active zone to become the RRP

Question 23

What is the reserve pool?

Answer 23

The vesicles containing neurotransmitter which are furthest away from the active zone

Question 24

What is sensitisation of the gill withdrawal reflex?

Answer 24

The gill withdrawal reflex is a lot stronger when preceded by a noxious stimulus

Question 25

How does sensitisation happen in the gill withdrawal reflex? (3)

Answer 25

- L29 sensory neuron senses the noxious stimulus and releases serotonin - Activates 5-HT receptor on the first sensory neuron, activates adenylyl cyclase which produces cAMP, activates pkA - pkA phosphorylates and inactivates K+ channels = longer presynaptic neuron depolarisation so more vesicles are released onto the motor neuoron

Question 26

What is the molecular mechanism of sensitisation?

Answer 26

Serotonin-ergic feedback from an additional sensory neuron

Question 27

What is associative learning? (2)

Answer 27

- Association of a conditioned stimulus with a non-conditioned stimulus e.g. Pavlov's dogs - Timing is critical

Question 28

What is the difference between sensitisation and associative learning?

Answer 28

The 2 stimuli need to happen at the same time in associative learning but no in sensitisation

Question 29

What is the mechanism of associative learning? (2)

Answer 29

- Same mechanism as sensitisation but when the L29 neuron releases serotonin onto the sensory neuron the sensory neuron is already depolarised from the other stimulus - The Ca2+ influx in the sensory neuron stimulates adenylyl cyclase even more than the serotonin on its own so even more vesicles are released

Question 30

What are the 3 main protein kinases?

Answer 30

- pKA - camKII - pKC

Question 31

What activates pKA?

Answer 31

cAMP

Question 32

What activates camKII?

Answer 32

Ca2+

Question 33

What activates pKC?

Answer 33

Diacylglycerol (DAG)

Question 34

What happens in the late stages of memory formation? (2)

Answer 34

- Changes in the nucleus - MAPK can enter the nucleus and phosphorylate transcription factors changing gene expression, allows for long-term response