Learning and Memory

Question 1

What is an engram?

Answer 1

A memory trace (a synaptic circuit that when a memory is stored it gets maintained for as long as the memory)

Question 2

Why are memories stored?

Answer 2

A circuit that is established is easy to maintain in that pattern so a memory is stored like that as a result.

Question 3

What are the 3 stages of learning and memory?

Answer 3

Sensory stage

Short-term stage (what is open at the time, 90% of it is lost and the rest is stored in long-term storage)

Long-term storage (all consolidated short-term memories)

Question 4

What are the types of memory?

Answer 4

Declarative (explicit): Explaining how to walk home

Procedural (implicit or motor/skill): Skills follow this kind of memory (eg.playing guitar or driving)

Question 5

What are the temporal components of memory?

Answer 5

Short term memory

Long term memory (consists of memories that are consolidated)

Question 6

What is amnesia?

Answer 6

Results from traumatic event and is a loss of memory.

Question 7

What are the types of amnesia?

Answer 7

Retrograde amnesia (Can’t remember anything from before traumatic event)

Anterograde amnesia (inability to form new memories)

Question 8

Where are declarative memories stored?

Answer 8

Cerebral cortex

Question 9

Where are procedural memories stored?

Answer 9

In the cerebellum, basal ganglia, and spinal cord

Question 10

Where are declarative memories stored?

Answer 10

Cerebral cortex, however the entire cortex is responsible for storage and memory isn’t stored in a single particular location (the more tissue removed the more of a particular memory is lost)

Question 11

Where are procedural memories stored?

Answer 11

In the cerebellum, basal ganglia, and spinal cord

Question 12

Where is working memory located?

Answer 12

Prefrontal cortex

Question 13

Where does memory storage take place?

Answer 13

Hippocampus

Question 14

Where does memory recall take place?

Answer 14

Thalamus

Question 15

What happens when prefrontal cortex is damaged?

Answer 15

The ability to produce a delayed, planned response is gone.

Question 16

What happens to aging people’s prefrontal cortex?

Answer 16

It is reduced and that results in a reduced working memory

Question 17

How is short term memory consolidated?

Answer 17

Repetitive activation of a short term memory trace results in changes to brain on chemical/physiological/anatomical level which results in Long Term Memories

Question 18

In what manner are memories stored?

Answer 18

They are codified.

Memories of the same things are often stored together.

Question 19

Where is the hippocampus located?

Answer 19

In medial temporal lobe.

Question 20

What happens when both medial temporal lobes are removed from the brain?

Answer 20

Procedural memories can be formed but total failure to produce declarative memories.

Perception and intelligence are unaffected.

Question 21

What interactions does memory consolidation involve?

Answer 21

Interaction between hippocampus and many other parts of the cortex.

Question 22

What other functions besides short term memory are the hippocampi important for?

Answer 22

They are output pathways for reward and punishment centers of the limbic system

Question 23

How do the hippocampus and the limbic system work together to form memory storage?

Answer 23

If a memory is associated with pain/aversion it gets stored as a result of activation of punishment centers of the limbic system

Pleasure and happiness kind of sensations stimulate reward centers which also helps with memory storage.

Question 24

What happens when hippocampal neurones that were activated during storage of a memory are reactivated?

Answer 24

The memory is triggered again and induces behavioural expression of that memory

Question 25

What is the role of the thalamus in memory?

Answer 25

Thalamus likely plays a role in searching for stored memory

Question 26

What happens in the brain during an immediate memory?

Answer 26

Simple circuit keeps revertebrating with transient synaptic potentiation (due to neurotransmitter sitting in synapse)

Question 27

What happens in the brain during short-term memory?

Answer 27

Temporary physical/chemical change in pre- or post-synaptic membrane.

Question 28

What appens in the brain during long-term memory?

Answer 28

Results from more permanent structural (physical/chemical/genetic) changes in the cells

Question 29

What is habituation?

Answer 29

Learning to ignore stimuli that lack meaning as a result of suppressed response. (this is an example of negative learning [i.e negative feedback to intense responding to unimportant stimulus])

Question 30

What is Facilitation?

Answer 30

Learning to intensify response to stimulus.

This is an example of +ve learning [positive feedback]

Question 31

What is Facilitation?

Answer 31

Learning to intensify response to stimulus.

This is an example of +ve learning [positive feedback]

Question 32

How is negative memory conducted?

Answer 32

Inhibition of synaptic pathways and reduction of:

Neurotransmitter production

Ca2+ channels

Postsynaptic receptors

Synapses

2nd messengers (Changing gene expression)

Question 33

How is positive memory conducted?

Answer 33

Facilitation of synaptic pathways and potentiation of:

Neurotransmitter production

Ca2+ channels

Postsynaptic receptors

Synapses

2nd messengers (Changing gene expression)

Question 34

What is long term potentiation?

Answer 34

Firing rate is elevated in long-term potentiation of memories in the hippocampus.

Question 35

What changes happen in the brain during Long Term Potentiation in the hippocampus?

Answer 35

The cells involved change morphology in response to this event by obtaining dendritic spines where more synapses are produced.

Calcium free buffer resulted in no storage of memory despite having the same triggering event.

Question 36

How do cells of the hippocampus ‘talk’ to each other?

Answer 36

Via a glutamate synapse. The synapse in these neurons is really plastic making it

Question 37

What changes happen in neurons during long-term memory formation?

Answer 37

Hippocampus cells have 2 membrane bound receptors. 1 that is always open and is known as AMPA (non-NMDA receptors that are classical excitatory ligand-gated channels) and another that is closed off and blocked by Mg2+ which is released by repeated strong stimulation of postsynaptic cells.

Repeated strong stimulation of postsynaptic cells also leads to more expression of AMPA channels which fuse to post synaptic membranes there.

This makes postsynaptic neuron hyperexcitable.

Morphology of the cell is changed via calcium which enters through NMDA receptors and triggers phosphorylation cascades which activate transcription factors and change gene expression in the cells.

Retrograde messengers are then released to act on pre-synaptic molecules.

Question 38

What are the presynaptic mechanisms of LT memory potentiation?

Answer 38

Presynaptic changes involve increase in neurotransmitted vesicle release sites, increase in number of NT veiscles, and increase in number of presynaptic termini (they sprout more).

Question 39

What are the postsynaptic mechanisms of LT memory potentiation?

Answer 39

Long Term Potentiation or depression as a result of growth/remodelling of dendritic spines which results in rewiring that causes storage of similar memories in these circuits.

Question 40

Are new neurons produced in the brain for memory purposes?

Answer 40

Not very common but there are 2 regions in the brain that do such as the hippocampus and the olfactory system (Olfactory ensheathing glia produce new neurons every day)