Higher Cortical Function: Memory

Question 1

Define learning.

Define memory.

Answer 1

• Learning is the acquisition of knowledge.

- Memory is the retention of knowledge.

Question 2

What is declarative memory?

Give an example of a characteristic of declarative memory.

List and describe the types of declarative memory.

Answer 2

• Declarative memory is memory of factual information - the ‘what’.
• Declarative memory fades with time.

Types of declarative memory include:

1 - Semantic memory: memory of facts.

2 - Episodic memory: memory of events.

Question 3

What is non-declarative memory?

Give an example of a characteristic of non-declarative memory.

List and describe the types of non-declarative memory.

Answer 3

• Non-declarative memory is memory of skills, habits and behaviours - the ‘how’.
• Non-declarative memory is less likely fade with time.

1 - Procedural memory: memory of skills and habits.

2 - Conditioned responses, e.g. associative reflexes (such as Pavlov’s dogs).

3 - Emotional responses.

Question 4

What is the average capacity for short-term memory?

Answer 4

7 items is the average capacity for short-term memory.

Question 5

Define consolidation.

Answer 5

The process of converting short-term memory into long-term memory.

Question 6

What is working memory?

Answer 6

Working memory is the process where information is taken in and processed or factored in with other existing memory.

Question 7

What changes occur in the brain to cause memory loss?

Answer 7

Loss of synapses (not neurones).

Question 8

Define amnesia.

List 5 causes of amnesia.

Answer 8

Amnesia is memory loss secondary to other pathologies:

1 - Traumatic brain injury.

2 - Infection.

3 - Neurodegeneration, such as Alzheimer’s.

4 - Resection.

5 - Stroke.

Question 9

List and describe the types of amnesia.

Answer 9

1 - Retrograde amnesia: partial loss of (particularly declarative) memories that were established before the onset of amnesia.

2 - Anterograde amnesia: inability to form new memories following the onset of amnesia.

Question 10

What is Ribot’s law?

Answer 10

The idea that recent memories are more likely to be lost than older memories.

Question 11

Which area of the brain is responsible for declarative memory?

Where is this information held in the short-term and long-term?

Answer 11

• The hippocampuses of the medial temporal lobes are responsible for declarative memory.
• The temporal lobes are particularly important in the formation of new memories rather than retention of old memories. Other cortical areas are important for long-term memory.

Question 12

What changes occur in the brain during consolidation of memory?

Answer 12

• Memory moves from the hippocampuses of the medial temporal lobes to the neocortex.
• It travels through the hypothalamus, and then the thalamus before reaching the neocortex.

Question 13

Which structures of the thalamus are responsible for the conveying of memories from the hippocampuses of the medial temporal lobes to the neocortex?

Answer 13

Mammillary bodies.

Question 14

What is Korsakoff’s syndrome?

Give an example of a symptom of Korsakoff’s syndrome.

Answer 14

• Korsakoff’s syndrome is a syndrome characterised by episodic memory loss, most usually associated with alcohol abuse.
• It is caused by degeneration of mammillary bodies in the thalamus, meaning information can’t reach the neocortex for long-term memory formation.

Question 15

List the areas of the brain that are responsible for non-declarative memory.

Answer 15

Procedural:

1 - Cerebellum.

2 - Supplementary motor area.

3 - Basal ganglia.

Emotional:

4 - Amygdala.

Question 16

Why does Parkinson’s disease cause memory loss?

How is memory affected in Parkinson’s disease?

Answer 16

• Parkinson’s disease causes memory loss because it is caused by degeneration of the substantia nigra (one of the basal ganglia).
• In particular, patients suffering from Parkinson’s disease have a reduced ability to form new memories.

Question 17

Which area of the brain is responsible for working memory?

Answer 17

The prefrontal cortex is responsible for working memory.

Question 18

Why might patients suffering from ADHD and schizophrenia have a poor working memory?

Answer 18

Patients with ADHD and schizophrenia might have a poor working memory because they have damage to the frontal lobe, which is responsible for working memory.

Question 19

Define neuroplasticity.

Answer 19

Neuroplasticity includes changes in:

1 - Neurotransmission (long term potentiation).

2 - Synaptic structure.

Question 20

What is long-term potentiation?

Answer 20

• Long-term potentiation is a mechanism for change in neurotransmission that contributes to neuroplasticity:
• Repeated interactions between a presynaptic and postsynaptic neurone increases the sensitivity of the postsynaptic neurone to the activity of the presynaptic neurone.

Question 21

Describe the mechanism for long-term potentiation.

Answer 21

• In a synapse using glutamate at AMPA and NMDA receptors, glutamate binds to both AMPA and NMDA receptors to cause an excitatory postsynaptic potential.
• Activation of NMDA also causes Ca2+ influx, which enhances the activity of a kinase known as CAMKII.
• In the short term, enhanced CAMKII activity enhances AMPA activity.
• In the long term, CAMKII increases gene expression of AMPA receptors. This results in more AMPA activity, and therefore a greater excitatory postsynaptic potential.

Question 22

How does synaptic structure change contribute to neuroplasticity?

Answer 22

• Repeated interactions between a presynaptic and postsynaptic neurone causes the presynaptic neurone to form axon sprouts.
• Growth cones at the tips of the axon sprouts guide the axon sprouts to the postsynaptic neurone.
• The axon sprouts then form more synapses at the postsynaptic neurone.
• This increases the sensitivity of the postsynaptic neurone to the activity of the presynaptic neurone.

Question 23

How does age affect memory?

Answer 23

• Age results in a decrease in neuroplasticity.
• However, age does not result in the loss of synaptic connections that are responsible for memories that are already established.
• This means that age decreases a person’s ability to form new memories, but doesn’t necessary result in the loss of memories that are already established.

Question 24

What are nootropics?

Answer 24

Nootropics are drugs that improve cognitive function, including memory.

Question 25

Give an example of a pharmacological suppressor of memory.

Why might this be useful?

Answer 25

• NMDA antagonists such as ketamine are used as suppressors of memory.
• It can be used clinically for patients with post-traumatic stress disorder, where memories of traumatic events are enhanced.

Question 26

What is sensory memory?

Describe the flow of information in the brain starting from sensory memory.

Answer 26

• Sensory memory is the temporary storage of information in the brain in the few fractions of a second after a stimulus is perceived.
• Information in the sensory memory is held in the brain whilst it is being moved to the short-term memory.
• With consolidation, this information can become long-term memory.