Molecular Neurobiology of Learning Behavior and Memory: Procedural Memory and Aplysia

Question 1

Neurobiology of memory

Answer 1

Identify where and how different types of information are stored

Question 2

Types of memory

Answer 2

declarative (explicit) and procedural (implicit) memories

Question 3

Difference in types of memory pathways

Answer 3

Declarative memory diffusely distributed, procedural memory robust and simple pathways

Question 4

Types of procedural learning

Answer 4

Non associative learning and associative learning

Question 5

Nonassociative learning

Answer 5

Habituation (learning to ignore stimulus) and sensitization (learning to intensity response to stimuli)

Question 6

Example of sensitization

Answer 6

driving along; hear an ambulance. Walking; sudden darkness, senses more heightened

Question 7

Associative learning

Answer 7

Classical conditioning and Instrumental or Operant Conditioning

Question 8

Classical conditioning

Answer 8

Pavlov
food->dog drool
tuning fork->no drool
food + tuning fork-> dog drool
tuning fork-> dog drool (conditioned stimulus->conditioned response)

A conditional stimulus does not evoke a response until conditioning

Question 9

Instrumental/Operant conditioning

Answer 9

Behavior triggers reward or avoidance of aversive stimulus (much quicker).

Lever to stop shock. Lever to receive food.

Question 10

Why are the neural circuits of operant conditioned responses more complex?

Answer 10

Due to added variable of motivation. Animal has to want the food and NOT want to be electrocuted.
(Depressed rat won’t care.)

Question 11

Experimental advantages of using invertebrate nervous system

Answer 11

Small NS with large, identifiable neurons, identifiable circuits, and simple genetics.

Question 12

What is aplysia

Answer 12

a squishy sea slug used as a model for studying and understanding the neural basis of learning

Question 13

What is the gill withdrawal reflex in aplysia

Answer 13

A defensive response so fish won’t attack. Aplysia withdraws its gills in response to prodding or water jet on siphon.

Question 14

What did Eric Kandel do with aplysia?

Answer 14

Measured the duration of the gill withdrawal reflex in response to habituation and sensitization of the gill withdrawal reflex

Question 15

Nonassociative learning in aplysia: habituation of gill withdrawal reflex

Answer 15

Repeat the stimulus-> less pronounced reflex.

Question 16

At what point in the aplysia neural circuit does habituation of the gill withdrawal reflex occur?

Answer 16

Changes at the synaptic level drive these processes. A modification of synaptic output via Hebbian process at the synapse of the sensory neuron on the motor neuron.

Question 17

What changes occur that lead to habituation in aplysia?

Answer 17

A decrease in NT released from the presynaptic terminal of the sensory neuron. (NOT a decrease in receptors.)

Question 18

How does the NT get released? How is this related to habituation in aplysia?

Answer 18

Ca2+ flux -> NT release.

Impact on Ca2+ channel -> change conformation o they don’t allow as much Ca2+ in in response to habituation stimuli

Question 19

Sensitization of the gill-withdrawl reflex requires..

Answer 19

Input from another sensory neuron (L29)

Question 20

What is the process of sensitizing the gill-withdrawal reflex?

Answer 20

1. Shock aplysia 2. Shock and then jet water -> gill reflex much more pronounced and longer.
   Increase shocks -> increase reflex

Question 21

What leads to this sensitization in alysia?

Answer 21

Some enhanced form of transmission that is persistent long-term

Question 22

How is L29 involved in the sensitization of the gill-withdrawal reflex?

Answer 22

Shock-> L29 excited -> L29 triggers release of 5HT-> 5HT impact on presynaptic terminal of sensory neuron

Question 23

What does 5HT (seratonin) do in this sensitization process in aplysia?

Answer 23

5HT typically bonds to metabotropic receptor-> activates a g protein-> activates adenyl cyclase -> converts ATP to cAMP -> increase in cAMP in the presynaptic terminal of sensory neuron -> activates kinase PKA -> PKA phosphorylates K+ channel -> enhanced depolarization and NT release (glutamate)

Question 24

What does phosphorylating the K+ channel do?

Answer 24

Makes the channel less able to sustain K+ efflux -> cannot repolarize -> enhanced depolarization and NT release (glutamate)-> longer AP

Question 25

Learning and memory can result from modifications of

Answer 25

synaptic transmission

Question 26

synaptic modification can be triggered by

Answer 26

conversion of neural activity into intracellular second messengers

Question 27

Memories can result from

Answer 27

alterations in existing synaptic proteins (K+ channel, for example.)

Question 28

L29 acts on the

Answer 28

presynaptic terminal of the sensory neuron (before the motor neuron).