Memory and Cognition

Question 1

What are the three key components of learning and memory?

Answer 1

• Hippocampus – formation of memories
• Cortex – storage of memories
• Thalamus – searches and accesses memories

Question 2

What does cognition describe?

Answer 2

All sensory info to make sense of a situation

Question 3

What does the ability to make sense require?

Answer 3

An ability to remember events and learn from them, and learning and remembering requires motivation

Require all three for normal memory to take place

Question 4

Describe the processing required for cognition

Answer 4

Most of the cerebrum is Association areas which integrate information from multiple sources, rather than being concerned with one specific function. The brain can therefore be thought of as parallel processing units.

Question 5

What is the limbic system?

Answer 5

Memories are formed in the limbic system and it gives events emotional significance which is essential for memory

Question 6

What does the limbic system have connections with and what is the importance of this?

Answer 6

The limbic system represents the ‘old cortex’, but has important connections with the ‘neo’ cortex, in particular the temporal and frontal lobes, which allows us to make sense of situations through learning.

Question 7

What are the four distinct areas of the limbic system?

Answer 7

• Hypothalamus (associated with ANS responses)
• Hippocampus (associated with memory)
• Cingulate gyrus
• Amydala (associated with emotion)

Question 8

What are the distinct areas of the limbic system responsible for?

Answer 8

Instinctive behaviour i.e. thirst, sex, hunger, and emotive behaviour which is drive by seeking reward or avoiding punishment

Question 9

What are the reward areas?

Answer 9

Electrical stimulation of certain areas in the limbic system in conscious patient intense feelings of well-being, euphoria and sexual arousal

Question 10

What are the punishment areas?

Answer 10

Nearby areas to reward areas elicit terror, anger or pain when electrically stimulated

Question 11

Why are reward and punishment are central aspects to learning?

Answer 11

They form the ‘affective components’ if sensory experiences. Motivation to learn comes from gaining a reward (passing an exam) or avoiding ‘punishment’ (resitting an exam) – gives a task significance.

Experiences that are neither rewarding or punishing (insignificant experiences) are barely remembered.

Question 12

What areas of the brain assess the significance of an event?

Answer 12

The frontal cortex and its association with the reward/punishment centres in the limbic system assess the significance of an event. If deemed insignificant, forgotten.

Question 13

What is the significance of the hippocampus?

Answer 13

Almost all sensory information goes through the hippocampus, which in turn relays information to other limbic system structures

Essential for the learning and formation of memories

Question 14

What is the effect of bilateral hippocampal damage?

Answer 14

Still have immediate (sensory) memory (seconds in length) and intact long-term memory (from time before damage), but are unable to form new long-term memories

Question 15

What are the four different types of memory?

Answer 15

• Immediate or sensory memory
• Short-term memory
• Intermediate long-term memory
• Long-term memory

Question 16

Describe immediate or sensory memory

Answer 16

• A few seconds
• Ability to hold experiences in the mind for a few seconds
• Based on different sensory modalities
• Visual memory decays fastest and auditory ones slowest

Question 17

Describe short-term memory

Answer 17

• Seconds - hours
• Used for short term tasks such as dialling a phone number, mental arithmetic, reading a sentence
• Associated with reverberating circuits.

Question 18

Describe intermediate long-term memory

Answer 18

• Hours to weeks i.e. what you did last weekend

* Associated with chemical adaptation at the presynaptic terminal

Question 19

Describe long-term memory

Answer 19

• Can be lifelong i.e. where you grew up and your childhood friends
• Associated with structural changes in synaptic connections

Question 20

What does short-term memory depend on?

Answer 20

Reverberating circuits i.e. they need to be constantly refreshed

Question 21

How does a reverberating circuit work?

Answer 21

Each synapse in a reverberating circuit is excitatory and hence a brief excitatory stimulus at A will cause a long lasting neuronal activity in B, as the reverberating circuit neurone continue to excite all neurons in the pathway.

Question 22

How does the reverberating circuit in short-term memory work to store memories?

Answer 22

Keeps the evanescent short-term memory alive. If deemed significant eventually this reverberation results in consolidation of the memory in long term memory storage.

If it is deemed insignificant then the reverberation fades and no consolidation occurs.

Question 23

How does amnesia occur?

Answer 23

If reverberation is disrupted i.e. following a head injury or infection, especially if it involves the hippocampus and/or thalamus, memory loss normally occurs

Question 24

What are the two types of amnesia?

Answer 24

1. Anterograde - cannot form new memories

2. Retrograde - cannot access old memories

Question 25

Describe anterograde amnesia

Answer 25

Inability to recall events that happen after the injury. Depending on the severity of the injury, this can be short liver or permanent.

Question 26

What is the effect of the destruction of the hippocampus?

Answer 26

Permanent inability to form new memories (anterograde amnesia)

Question 27

Describe retrograde amnesia

Answer 27

Can’t remember events leading up to the injury, although recall of events that happened a long time ago is usually unaffected, probably because they are better rehearsed and more deeply ingrained.

Question 28

What does retrograde amnesia often present with?

Answer 28

Anterograde amnesia.

However, if only the thalamus is damaged, and the hippocampus spared, only retrograde amnesia is seen.
- Suggests thalamus is required for ‘searching’ our existing memory bank

Question 29

What is the role of the hippocampus, cerebrum and thalamus in memory?

Answer 29

Memory requires ability to form (hippocampus)), store (cerebrum) AND search (thalamus) our memories.

Question 30

What is the physiology behind immediate long-term memory?

Answer 30

Involves chemical changes in presynaptic neurons:

Increasing Ca+ entry to presynaptic terminals, which increases neurotransmitter release.

Question 31

What is the physiology of long-term memory?

Answer 31

Involves structural changes at synapses:

1. Increases in NT release sites on presynaptic membrane
2. Increase in number of NT vesicles stores and released
3. Increase in number of presynaptic terminals

Also increased amplitude in graded membrane potential (EPSP) in post-synaptic cell occurs, strengthening synapse.

Question 32

What is long term potentiation?

Answer 32

Occurs in long-term memory - increased amplitude in graded membrane potential (EPSP) in the post-synaptic cell occurs. This strengthens the synapse.

Question 33

What are the two types of long-term memory?

Answer 33

• Declarative or Explicit Memory

* Procedural/Reflective/Implicit memory

Question 34

What is declarative or explicit memory?

Answer 34

• Abstract memory for events (episodic memory) and for words, rules and language (semantic memory).
• Relies heavily on the hippocampus

Question 35

What is Procedural/Reflective/Implicit Memory?

Answer 35

• Acquired slowly through repetition
• Include motor memory for acquired motor skills such as playing sport, and rules based learning i.e. driving rules.
• Based mainly in the cerebellum
• Independent of hippocampus

Question 36

How is STM converted to LTM?

Answer 36

Through consolidation

Question 37

What is consolidation?

Answer 37

Selective strengthening of synaptic connections through repetition (for minutes to hours).

Question 38

What is memory before consolidation?

Answer 38

Memory exists as electrical activity and is vulnerable to being wiped out

Question 39

What happens to new memories one the frontal cortex and its association areas deem that it’s significant?

Answer 39

New memories are ‘coded’ then stored in the sensory and association areas of the cortex. Coding results in new memories being stored alongside other existing memories the brain deems similar.

Question 40

What is the papez circuit?

Answer 40

Fundamental component of the limbic system. It is a closed neural circuitry that starts and ends in the hippocampus.

Hippocampus -> mammillary bodies -> anterior thalamus -> cingulate gyrus (repeat)

Question 41

What does consolidation involve?

Answer 41

Reverberating activity continues between the Papez circuit, the frontal cortex, the sensory and association areas until the consolidation process is complete.

Question 42

Is the a system to how memories are stored?

Answer 42

Different components of the memory are laid down in different parts of the cortex, i.e. visual component in the visual cortex, auditory in auditory cortex etc.