Learning And Memory

Question 1

Define the term “Learning”

Answer 1

Acquisition of new information

Question 2

Define the term “memory”

Answer 2

Retention of learned information

Question 3

What are the 2 types of memory?

Answer 3

• Declarative memory (explicit): Facts and events - Hippocampus
• Non-declarative memory (implicit): Procedural memory, motor skills, skills - Stratium

Question 4

List some types of declarative memories

Answer 4

• Working memory: Temporary storage, lasting seconds
• Short term memories: Facts and events in STM, Subset are converted to LTM
• Long term memories: Recalled months or years later

Question 5

List some non declarative memories

Answer 5

• Procedural memory: Skills & habits
• Skeletal musculature (Classical conditioning)
• Emotional response (Classical conditioning)

Question 6

Describe the process of memory being converted from the STM to the LTM

Answer 6

Sensory information -> either working memory or STM -> LTM via consolidation and with time

Question 7

Where is the prefrontal cortex found?
What is special about this area of the brain in regards to humans?

Answer 7

• Found in the frontal lobe
• Primates have a large frontal lobe
• Meaning they’ve got a large/well developed prefrontal cortex

Question 8

What is the function of the prefrontal cortex?

Answer 8

• Self awareness
• Capacity for planning and problem solving
• Higher order thinking
• Rational thinking

Question 9

How does the working memory activity in the monkey prefrontal cortex work?

Answer 9

• Produces a delayed response
• First there is a cue period
• This is then followed by a 10 second delayed response
• Finally the monkey undergoes a choice period

Question 10

What other brain regions are involved in the delayed response saccade task?

Answer 10

• Anterior intraparietal area
• Lateral intraparietal area
• Parietal region reach

Question 11

How does these areas affect and cause the delayed response?

Answer 11

• First the target is flashed whilst the monkey is staring at the fixation point
• The target then moves whilst the monkey is still staring at the fixation point (delay stage)
• The monkey then finally started to look at the target (Saccade stage)

Question 12

Where are memories stored?

Answer 12

• In general, they can be stored throughout the brain
• In neurons, they can be stored in the engram

Question 13

Describe Hebb’s cell assembly and memory storage model (PART 1)

Answer 13

• Came up with the idea neurons don’t exist in isolation but instead in a network
• As a consequence, he presented an external stimulus (circle)
• This resulted in the activation of the cell assembly by a stimulus

Question 14

Describe Hebb’s cell assembly and memory storage model (PART 2)

Answer 14

• revertibrating activity continues activation after the stimulus is removed
• The hebbian modification then strengthens the reciprocal connections between neurons that are active at the same time
• The strengthened connections of the cell assembly contain the engram for the stimulus

Question 15

Describe Hebb’s cell assembly and memory storage model (PART 3)

Answer 15

• After learning, partial information activation of the assembly leads to activation of the entire representation of the stimulus
• Producing a circle in the end

Question 16

What occurs in the consolidation stage of memory?

Answer 16

Memory is moved to different parts of the brain so they can be retrieved for long term memory

Question 17

What does the consolidation stage involve?

Answer 17

Involvement of the temporal medial lobe

Question 18

How does information flow from the cortex to the hippocampus?

Answer 18

There is a flow of information into the hippocampus via
- Parahippocampal cortex
- Perirhinal cortex
- Entorhinal cortex
These structures flow into the hippocampus

Question 19

How does information flow through the medial temporal lobe?

Answer 19

Sensory information -> Cortical association areas -> Parahippocampal and rhinal cortical areas -> Hippocampus -> Thalamus, hippocampus via fornix

Question 20

Describe amnesia

Answer 20

A serious loss of memory or ability to learn
- Causes: Concussion, chronic alcoholism, encephalitis, brain tumours, stroke

Question 21

What are the 2 types of amnesia?

Answer 21

• Retrograde amnesia: No memory before the time of trauma
• Anterograde amnesia: No new memories after the time of trauma

Question 22

Who was Henry Molaison (HM)?

Answer 22

• Had a bicycle accident at age
• Developed epilepsy
• In 1953 was referred to William Scoville at Hartford hospital
• Scoville localised the epilepsy to the right and left medial temporal lobes of HM’s brain and removed both LTMs

Question 23

What was the result of the surgery?

Answer 23

• The surgery was effective in reducing occurrence of seizures
• However it had a devastating side effect
• HM lost the ability to form new long term memories but remembered events before the surgery
• However he was able to learn new motor skills but didn’t remember learning them

Question 24

What was the impact of HM on memory research?

Answer 24

• Findings from HM shaped subsequent memory research
• Established the memories separateness from other cognitive functions
• No overall intellectual loss or perceptual disorders in HM

Question 25

How has the role of the hippocampus in spatial memory been established?

Answer 25

Through the Morris water maze

Question 26

What is the Morris water maze?

Answer 26

- A large pool of water which is opaque - Has a hidden platform in the water - When you place a rodent in the water, it’s natural reaction is to get out - In the morris water maze, it will swim around once it finds the platform then will climb onto it and get out - After repeated exposure, the rat remembers the platform and gets out asap

Question 27

What does learning the morris water maze require?

Answer 27

A hippocampus

Question 28

What happens if you block neuronal activity in the hippocampus?

Answer 28

- By using a molecule such as glutamate, you can block the learning process in the hippocampus - Therefore the rat will continue to swim around before finding the platform

Question 29

What are place cells?

Answer 29

- Fire when an animal is in a specific place - Place fields dynamic

Question 30

What happens when a place cell is activated?

Answer 30

- Once the rat is placed in a specific environment, there is activity in the place cells - That is specific for the subject being in a specific place

Question 31

What happens if the subject moves to a different part of the environment?

Answer 31

- There will be increased activity in the other place cells - There is just a differential firing pattern between the cells in different locations of the cell

Question 32

What are the two models of memory consolidation?

Answer 32

- Standard model of memory consolidation - Multiple trace model of consolidation - Both dependent upon synaptic plasticity: the biological process by which specific patterns of synaptic activity result in changes in synaptic strength

Question 33

Describe the standard model of memory consolidation

Answer 33

- Information from neocortex areas associated with sensory systems sent to medial temporal lobe for processing - Synaptic consolidation, system consolidation - Post consolidation, hippocampus not necessary

Question 34

Describe the multiple trace model of consolidation

Answer 34

- Hippocampal involvement is continued - Multiple memory traces

Question 35

Describe the model of distributed memory

Answer 35

- Instead of one specific neuron in the brain holding specific information for one memory - It distributed memories across neuronal populations

Question 36

How does the model of distributed memory work

Answer 36

- Depending on when the individual is exposed to the memory - Before learning, each cell has the same base line firing - After learning, each cell has a corresponding change in activity between neurons

Question 37

How does the change in activity occur across multiple neurons?

Answer 37

- Changes in the neuronal response can be explained by synaptic plasticity - The trisynaptic circuit of the hippocampus is often used in studies of this phenomenon

Question 38

Describe what happens in the trisynaptic circuit

Answer 38

- Information flows from entorhinal cortex via performant path to the dentate gyrus - Mossy fibres originate from dentate gyrus and synapse upon pyramidal neurons in CA3 Hippocampal regions - Axons from CA3 synapse upon pyramidal neurons in CA1 Hippocampal region

Question 39

Describe the long term potentiation

Answer 39

- They essentially stimulated the shape of collaterals and recorded the CA1 neurons via a record EPSP electrode - They found depending on the frequency of stimulation, you got a change in the excitatory post synaptic potential

Question 40

Describe the long term potentiation (PART 2)

Answer 40

- If you recorded post synaptically, there wasn’t really a change in respect to what’s happening in this point of view -If you changed the frequency of stimulation, you find the magnitude of the excitatory synaptic potential, frequency of stimulation greatly increased - This is a potentiation of the excitatory post synaptic potentially recording since it can be maintained over a period of time

Question 41

In short, What is synaptic plasticity?

Answer 41

If you continue to stimulate neurons at a very high frequency, you will get increased responsivity

Question 42

What underlies the long term potentiation response?

Answer 42

- Glutamate receptors mediate excitatory synaptic transmission via NMDA and AMPA receptors - Normally when Glutamate binds to AMPA receptors, you get activation of NMDA receptors - This then causes calcium to flood in through NMDA receptors

Question 43

What happens if excess calcium enters into the cell?

Answer 43

- Causes activation of Calcium calmodulin kinases which has a few affects - Increases phosphorylation of AMPA receptors in the membrane increasing their responsivity which magnifies the size of the post synaptic response - This also causes a second effect of increased expression of receptors in the post synaptic membrane

Question 44

What are the structural changes following Long term potentiation?

Answer 44

Spine growth