Memory and Cognition

Question 1

what is cognition?

Answer 1

it is the highest order of the brain function and describes the integration of all sensory information to make sense of a situation

Question 2

what does making sense require?

Answer 2

an ability to remember events and learn from them- learning and memory required motivation

Question 3

what is neuronal plasticity?

Answer 3

the ability of central neurone to adapt their neuronal connections in responses to learning experiences

Question 4

what are the 3 key required components of learning and memory?

Answer 4

hippocampus= formation of memories
cortex= storage of memories
thalamus= searches and accesses memories

Question 5

what is the limbic system?

Answer 5

where memories are formed and gives events emotional significance which is essential for memory

Question 6

what are the 4 areas of the limbic system?

Answer 6

hypothalamus= emotion and ANS responses
hippocampus= learning and memory
cingulate gyrus= emotion
amygdala= emotion and memory

Question 7

how is motivation driven?

Answer 7

seeking reward or avoiding punishment from instinctive behaviours like hunger, sex etc

Question 8

what happens to experiences that are neither rewarding or punishing?

Answer 8

these are deemed insignificant experiences and are barely remembered so the brain only gives attention to experiences it deems significant

Question 9

what part of the brain decides significance and where does sensory information then pass?

Answer 9

the frontal cortex and its association with reward/punishment centres in the limbic system - through the hippocampus which relays it to other limbic structures

Question 10

what would bilateral damage to the hippocampus cause?

Answer 10

immediate (sensory) memory (seconds in length) and intact long-term memory (from time before damage) but unable to form new long-term memories, reflexive memory (motor skills) remain intact

Question 11

how long are sensory memories normally held in the brain?

Answer 11

a few seconds but varies depending on the sensory modality- visual memories decay fastest (<1s) and auditory ones the slowest (<4s)

Question 12

describe a short term memory.

Answer 12

lasts seconds to hours and is used for short term tasks like dialling a phone number or reading a sentence, it is an electrical phenomenon which depends on maintained excitation from reverberating circuits

Question 13

what are reverberating circuits?

Answer 13

keep the brief short-term memory alive by constantly refreshing it

Question 14

what happens if the memory is deemed significant?

Answer 14

the memory is consolidated into a long-term memory and stored

Question 15

what happens if the memory is deemed insignificant?

Answer 15

the reverberation faces and no consolidation occurs

Question 16

what is amnesia?

Answer 16

if reverberation is disrupted eg by head injury or infection then memory is lost

Question 17

what are the 2 types of amnesia?

Answer 17

anterograde= cannot form new memories
retrograde= cannot access (more recent) old memories

Question 18

describe anterograde amnesia.

Answer 18

inability to recall events happening after the injury, depending on. the severity of the injury can be short lived or permanent (eg destruction of the hippocampus)

Question 19

when would retrograde amnesia be seen?

Answer 19

if only the thalamus is damaged and the hippocampus is spared which suggests that the thalamus is required for searching our existing memory back

Question 20

describe immediate long-term memory.

Answer 20

lasts hours to weeks eg what you did last week and is associated with chemical adaptation at the presynaptic terminal- increasing Ca++ entry to presynaptic terminals increases neurotransmitter release which increases excitation of post-synaptic neurones

Question 21

describe long-term memory.

Answer 21

can be lifelong eg where you grew up and is associated with structural changes in synaptic connections= increase in NT release sites on presynaptic membrane, increase in number of NT vesicles stored and released and increase in number of postsynaptic terminals

Question 22

what is long-term potentiation?

Answer 22

at the same time as the structural changes the amplitude in the graded membrane potential (EPSP) in the post-synaptic cells increases which strengthens the synapse

Question 23

what are the 2 types of long-term memory?

Answer 23

declarative or explicit memory

procedural/reflexive/implicit memory

Question 24

what is declarative or explicit memory?

Answer 24

abstract memory for events (episodic memory) and for words, rule and language (semantic memory) and relies heavily on the hippocampus

Question 25

what is procedural/reflexive/implicit memory?

Answer 25

acquired slowly through repetition, includes motor memory for acquired motor skilll and rules-based learning and thinking about these skills often impair performance and is mainly based in the cerebellum

Question 26

what happens to new memories?

Answer 26

there are coded in the sensory and assocaition areas of the cortex where they are stored alongside other existing memories the brain deems similar

Question 27

what happens if an experience is considered useful?

Answer 27

the frontal cortex ‘gates” the so-called Paper circuit: cingulate gyrus- hipoocampus- anterior thalamus- mammillary bodies and the reverterbrating activity continues between the paper circuit, frontal Cortex, sensory and association areas until consolidation is complete

Question 28

for example where would the visual component of memory be stored?

Answer 28

the visual cortex as different components of memory are laid down in the relevant parts of the cortex

Question 29

what is Korsakoff’s syndrome?

Answer 29

related to chronic alcoholism and is vitamin B1 deficiency which leads to damage of the limbic system structures and so ability to consolidate memory is impaired

Question 30

what happens in Alzheimers disease?

Answer 30

severe loss of cholinergic neurones throughout the brain including the hippocampus causing gross impairment of memory

Question 31

why is REM sleep important for memory?

Answer 31

dreaming may enable memory consolidation and reinforce weak circuits as subject deprived of REM sleep show significant impairment of memory consolidation for complex cognitive tasks