Higher Cortical Function: Memory

Question 1

Define learning

Define memory

Answer 1

Learning = acquisition of knowledge 
Memory = retention of knowledge

Question 2

How can memory be classified?

Answer 2

• nature of memory e.g. declarative vs non-declarative

- duration e.g. short vs long term

Question 3

For how long are the following stored?

• sensory memory
• short term memory
• long term memory

Answer 3

• sensory memory = <1 second
• short term memory = >1 min
• long term memory = lifetime

Question 4

Define the following

1. explicit vs implicit memory
2. declarative vs procedural memory
3. episodic vs semantic memory

Answer 4

1. explicit = conscious 
implicit = unconscious 
2. declarative = facts and events 
procedural = skills, tasks
3. episodic = events and experiences 
semantic = facts and concepts

Question 5

Draw the memory tree

Answer 5

see lecture notes

Question 6

Describe the nature of declarative memory

What are the two types of declarative memory?

Answer 6

• explicit
• consciously aware
• able to describe in words
• fades with type
  Two types
• episodic = events, experiences
• semantic = facts, concepts

Question 7

Describe the nature of non-declarative memory

Give two examples of conditioned responses

Answer 7

• implicit
• skills, habits, behaviours
• procedural memory e.g motor tasks, acquiring experience
  Conditioned responses:
• associative reflexes e.g Pavlov’s dog
• emotional response –> strengthens declarative memory

Question 8

What is the functions of sensory memory?

How long is it stored?

Answer 8

• sensory processing

- lasts for fractions of a second

Question 9

What is meant by working memory? What is its function?

Answer 9

Working memory is a cognitive system with a limited capacity that is responsible for temporarily holding information available for processing. Working memory is important for reasoning and the guidance of decision making and behavior.

Question 10

What are some causes of amnesia?

Answer 10

TBI
neurodegeneration
resection
stroke

Question 11

What are the two types of amnesia and how are they different?

Answer 11

Retrograde amnesia = can’t remember anything before the insult
Anterograde amnesia = can’t form new memories after the insult

Question 12

What is Ribot’s law?

Answer 12

• Retrograde amnesia is not usually complete

- Ribot’s Law = recent memories are more likely to be lost than remote ones

Question 13

What is the anatomical location for declarative memory?

What disease provides evidence for this?

Answer 13

• medial temporal lobes
• evidence for this is lesions
• the pathology of alzheimers disease –> lose episodic, then semantic memory

Question 14

What is the declarative memory pathway?

Answer 14

sensory info –> rhinal cortices and hippocampus –> neocortex

hippocampus –> hypothalamus (MB’s) –> thalamus –> neocortex

Question 15

What memory is lost in Korsakoff’s?

Answer 15

episodic memory

- mamillary bodies in hypothalamus key step in memory formation

Question 16

What is the anatomical location procedural memory?

What disease provides evidence for this?

Answer 16

• supplementary motor area, basal ganglia and cerebellum
• ## parkinsons disease, difficult to acquire new procedural skills

Question 17

What is the anatomical location of working memory?

What is the evidence for this?

Answer 17

• prefrontal cortex

- evidence in ADHD and schizophrenia

Question 18

Describe the HM case study?

Answer 18

• bilateral temporal lobectomy –> severe anterograde amnesia for declarative memory
• childhood memory intact
• temporal lobe required for new declarative memories but not old
• no effect on procedural memory

Question 19

How do neurones store memories?

Answer 19

• change in neurotransmission
• change in synaptic structure
• neuronal plasticity = dynamic synapse formation/retraction
• long term potentiation

Question 20

Where was long term potentiation first shown?

Answer 20

• hippocampus in vitro

Question 21

What is long term potentiation?

Answer 21

• neurones in the hippocampus have a baseline level of activity
• if you stimulate the hippocampus with lots of afferent input, then remove the input
• the baseline activity of the neurones has increases
• the nature of these neurones has been changed

Question 22

What kind of memory is LTP shown in?

Answer 22

declarative memory

Question 23

What is happening at the synapse during LTP?

Answer 23

Glutamate transmission critical in LTP
- glutamate normally binds to AMPA receptor
- if stimulated, you unblock NMDA receptors and so get AMPA and NMDA activity
- NMDA allows calcium entry
- leads to changed gene expression and altered kinase activity especially CAMKII
- CAMKII affects cellular processes = biological equivalent of memory
LTP also triggers physical transformation of neurones
- spine formation

Question 24

What are key theories for the biological basis of memory formation?

Answer 24

Long term potentiation

• changes in baseline activity
• changes in receptor activity on postsynaptic knob
• calcium entry –> changes to cellular processes
• enzyme CAMKII activity
• physical changes e.g. spine formation in response to glutamate

Question 25

How can be manipulate memory?

Answer 25

Pharmacological
- enhancement by nootropics, NMDA agonists enhance memory formation in animals, other mechanisms target ACh transmission e.g. ACh loss in Alzeheimer’s
- suppression by NMDA antagonists e.g. ketamine
Non-pharmacological
- CBT - changes in network activity