Memory and Cognition

Question 1

What is cognition is basic terms?

Answer 1

The integration of all sensory information to make sense of a situation

Question 2

What are the 3 key parts of the brain responsible for memory, and their function with regard to memory?

Answer 2

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

Question 3

What are the four distinct areas of the limbic system?

Answer 3

• Hypothalamus
• Hippocampus
• Cingulate gyrus
• Amygdala

Question 4

How does the limbic system give tasks significance and motivate learning?

Answer 4

It assigns emotional value to tasks

There are reward and punishment areas of the limbic system, motivation to learn comes from gaining a reward or avoiding a punishment

Question 5

How does the limbic system determine whether something is worth remembering?

Answer 5

Experiences that are either rewarding or punishing are deemed significant

Experiences that are neither are insignificant and so quickly forgotten

Question 6

What is the role of the hippocampus?

What symptoms may be seen in a patient with bilateral hippocampal damage?

Answer 6

• Formation of memories
• Patient still has sensory (immediate) memory (seconds in length), but loses ability to form new long term memories. Still has memories from before damage
  (anterograde amnesia)

Question 7

What are the 4 divisions of memory? What structures in the brain are they facilitated by?

Answer 7

• Immediate/sensory memory: few seconds. Based on different sensory modalities
• Short term memory: seconds-hours. Associated with reverberating circuits
• Intermediate long-term memory: hours to weeks. Associated w chemical adaptation at presynaptic terminal
• Long term memory: can be lifelong. Associated with structural changes in synaptic connections

Question 8

What is a reverberating circuit? What is it responsible for?

Answer 8

• Small circuit of excitatory neurons, when a depolarization comes by it can be cycled through the circuit on repeat. The depolarization is “remembered”
• Responsible for short term memory

Question 9

What happens to the depolarizations in reverberating circuits?

Answer 9

If deemed significant they become consolidated in long term memory, if not they get forgotten

Question 10

What happens if reverberation of a reverberating circuit is disrupted? (eg. head knock)

Answer 10

Memory loss results (amnesia)

Question 11

What are the two types of amnesia and the distinction between the two?

Answer 11

Anterograde - can’t form new memories

Retrograde - cannot access old memories

Question 12

How long does anterograde amnesia last?

Answer 12

Depends on the severity of the injury

Can be short lived or permanent

Question 13

How does retrograde amnesia usually present?

Answer 13

• Can’t remember events leading up to the injury, memories from long ago usually still in tact though
• Usually presents with anterograde amnesia, but if only thalamus is damaged and hippocampus spared it can present alone

Question 14

How is short term memory converted to long term memory?

Answer 14

It is consolidated

• Changes at the synapses of the brain (in the hippocampus?) cause the memory to become more fortified, less vulnerable to being wiped out
• The memory is then coded into the cortex where it is stored

Question 15

How is short term memory converted to intermediate long term memory?

Answer 15

Chemical changes at the presynaptic neurons

• Increasing Ca entry to presynaptic terminals causes increased neurotransmitter release (done by upping cAMP production from ATP - causes more Ca gates to open)

Question 16

How is intermediate long term memory converted to long term memory?

Answer 16

Four changes occur at the synapse:

1. Increase in neurotransmitter (NT) release sites on the presynaptic membrane 
2. Increase in number of NT vesicles stored and released 
3. Increase in number of presynaptic terminals 
4. Increase in amplitude of graded potential at the post-synaptic cell

Question 17

What is the effect of the synaptic/neural changes that occur as a memory goes from short to long term? What are these changes called?

Answer 17

The changes solidify the action potential propagation, all work to ensure the propagation of the AP is less likely to be wiped out

• Called: long term potentiation

Question 18

What are the two different types of long term memory and a brief description of each?

Answer 18

• Declarative/explicit memory: abstract memory for events (episodic memory) and for words, rules and language (semantic memory)
• Procedural/reflexive/implicit memory: acquired slowly through repetition (motor memory and rules based learning)

Question 19

How is the hippocampus involved in long term memory?

Answer 19

• Heavily involved in declarative/explicit memory

- Procedural/reflexive memory is independent of the hippocampus

Question 20

What parts of the brain determine whether an event is significant enough to be remembered?

Answer 20

• Determined by the frontal cortex and its association with the limbic system (reward/punishment system)
• Amygdala(?)
• Papez Circuit (assigns emotional significance)

Question 21

What is the name of the circuit that works with the frontal cortex to facilitate memory?

Answer 21

Papez circuit

Seems to assign emotional value to memories?

Question 22

How does the consolidation process occur?

Answer 22

Reverberating activity between the frontal cortex, Papez circuit and sensory association areas occurs until the memory is laid down and consolidated fully within its appropriate sensory association area

(Each time it reverberates seems to be reconsidered as emotionally significant, if it is still significant consolidation continues)

Question 23

Why are smells particularly powerful in evoking long term memories?

Answer 23

Because the olfactory cortex is heavily associated with the limbic system in the brain

Question 24

Effect of Korsakoff’s syndrome (chronic alcoholism) on the limbic system?

Answer 24

Vitamin B1 deficiency causes limbic system damage

Ability to consolidate memory is impaired

Question 25

What is REM sleep and how does it influence memory?

Answer 25

• Rapid eye movement sleep
• Important for consolidating memory, patients deprived of it show significant consolidation impairment
• Associated with dreaming, dreaming may enable memory consolidation of complex tasks

Question 26

What is the function of the Papez Circuit?

Answer 26

To establish the emotional significance of memories

Question 27

Describe the Papez Circuit

Answer 27

Hippocampus - Fornix - Mammillary Body - Thalamus - Cingulate Gyrus - Hippocampus