Memory and Cognition

Question 1

What is cognition?

Answer 1

HIghest order of brain function, involves thought processing.

It describes the integration of all sensory information to make sense of a situation

Question 2

How does changes in neoronal plasticity reflect learning?

Answer 2

Central neurones adapt their neuronal connections in response to learning experiences

Question 3

Most of the cerebrum is Association areas, what do these do?

Answer 3

Integrate information from multiple sources, rather than being concerned with one specific function

Question 4

Give examples of association areas

Answer 4

Motor association area

Sensory association area

Prefrontal association area

Visual association area

Auditory association area

Question 5

What are the three components of learning and memory and what are their functions?

Answer 5

Hippocampus – formation of memories

Cortex – storage of memories

Thalamus – searches and accesses memories

Question 6

Which brain system is involved with memory formation and emotional significance?

Responsible for istinctive behaviour - thirst, sex, hunger etc. and emotive behaviour are driven by seeking reward or avoiding punishment.

Answer 6

Limbic system

Question 7

What portions of the brain are included in the limbic system?

Answer 7

Limbic – cingulate gyrus, amygdala – particulary involved in emotion, hippocampus, hypothalamus

Question 8

How does emotion evoke an ANS response?

Answer 8

Hypothalamus links emotion to autonomic response

Question 9

Where does the limbic system make connections to in the brain?

Answer 9

The limbic system is part of the ‘old’ cortex and is described as the most primitive part of the cortex. It has important connections with the “neo” cortex, in particular the temporal and frontal lobes, which allow us to make sense of situations through learning.

Question 10

Where does the motivation to learn come from?

Answer 10

Comes from gaining a reward or avoiding a punishment - gives task significance

Question 11

Which memories are often forgotten?

Answer 11

Experiences that are neither rewarding or punishing (insignificant experiences)

Question 12

How is the significance of an event determined?

Answer 12

The forntal cortex and its association with the reward/punishment centres located in the limbic system are responsible for assessing the significance of an event

Question 13

Which part of the limbic system does almost all sensory information travel through?

Answer 13

The hippocampus, which in turn relays information to other limbic system structures

Question 14

What is the effect of bilateral hippocampal damage?

Answer 14

People with bilateral hippocampal damage 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.

Their reflexive memory (motor skills) remains intact.

Question 15

What are the categories of memory?

Answer 15

Immediate or sensory memory

Short - term memory

Immediate long-term memory

Long-term memory

Question 16

What is immediate or sensory memory?

Answer 16

A few seconds

The ability to hold experiences in the mind for a few seconds

Different sensory modalitites have different rates of decay

Visual memories decay fastest (<1s), auditory ones slowest (<4s).

Question 17

What is short term memory?

Answer 17

Seconds - hours

Used for short term tasks such as dialling a phone number, mental arithmetic and reading a senstence

Associated with reverberating circuits

Question 18

What is intermediate long-term memory?

Answer 18

Hours to weeks - what you did last weekend -

Association with chemical adaptation at the presynaptic terminal

Question 19

What is long term memory?

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

Question 20

What is short term memory dependant on?

Answer 20

Maintained excitation from reverberating circuits - they need to be constantly refreshed

Question 21

Describe how a brief stimulus at A will cause a long lasting neuronal activity in B?

Answer 21

Each synapse in a reverbating circuit is excitatory. Therefore in a reverberating circuit the neurones continue to excite all neurones in the pathway.

Question 22

What is the effect of the reverberaing circuit?

Answer 22

Keeps evanescent short term memory alive

Question 23

What happens if the memory is deemed significant?

Answer 23

Reverberation results in consolidation of the memory in long term memory storage

Consolidation involves selective strengthening of synaptic connections through repetition (for minutes to hours).

Question 24

What happens if a memory is deemed insignificant?

Answer 24

Reverberation fades and no consolidation occurs

Question 25

What is the result of disruption of reverberation?

Disruption can be the result of head injury, infection - especially if it involves the hippocampus and/or thalamus.

Answer 25

Memory loss normally results - amnesia

Question 26

What is enterograde and retrograde amnesia?

Answer 26

1. Anterograde – cannot form new memories - may be short lived or permanent depending on the severity of the injury
2. Retrograde – cannot access (more recent) old memories

Question 27

Which memories are often spared in the case of retrograde amnesia?

Answer 27

Retrograde amnesia, 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

How does retrograde amnesia often present?

Answer 28

Anterograde amnesia

If only the thalamus is damaged and the hippocampus is spared then only retrograde amnesia is seen

Suggests that the thalamus is reponsible for searching our existing memory banks

Question 29

What are the chemical changes in presynaptic terminals that occur in the intermediate long-term memory?

Answer 29

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

Question 30

What are the structural changes at synapses that occur in long term memory?

Answer 30

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

Question 31

What is meant by long term potentiation?

Answer 31

Increase in graded membrane potential (EPSP) in post - synaptic cell

Strengthens the synapse

Question 32

LTM is basically a well established, well rehearsed pattern of neuronal firing unique to that particular memory.

Answer 32

.

Question 33

What is declarative or explicit memory?

Answer 33

Abstract memory for events (episodic memory) and for words, rules and language (semantic memory).

Is based mainly in the hippocampus.

Question 34

What is Procedural/ Reflexive/Implicit Memory?

Answer 34

Acquired slowly through repetition. Includes motor memory for acquired motor skills such as playing tennis, and rules based learning such as, in the UK, always driving on the left.

Thinking about these skills (“memories”) often impairs performance!

Is based mainly in the cerebellum.

Is independent of hippocampus (remember Clive Wearing).

Question 35

Where else does consolidation occur?

Answer 35

Similar process occurs in the cerebellum during motor learning.

Question 36

Why is learning harder when you are tired?

Answer 36

Consolidation requires attention

Question 37

Where are coded memories stored?

Answer 37

Sensory association areas of the cortex alongside existing memories the brain deems similar

Question 38

When is entry to the papez circuit made possible?

Answer 38

When the frontal cortex and its association with the reward/punishment centres in the limbic system consider an experience significant or useful

Frontal cortex gates the papez circuit

Question 39

What does the papez circuit consist of?

Answer 39

Question 40

Which parts of the brain does reverberation occur?

Answer 40

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

Question 41

Where are visual components of memory and auditory components of memory laid down in the cortex?

Answer 41

Visual cortex and the auditory cortex respectively

Question 42

Why does chronic alcoholism lead to impairment in the consolidation of memory?

Answer 42

There is Vitamin B1 deficiency which leads to damage of limbic system structures. The ability to consolidate memory is impaired.

Question 43

What causes the impairment of memory in alzheimers?

Answer 43

There is a severe loss of cholinergic neurons throughout the brain, including the hippocampus. Gross impairment of memory.

Some improvement in Alzheimer’s may be seen with anti-cholinesterases, but underlying degeneration continues. Cause unknown.

Question 44

What is REM sleep like in korsakoff’s syndrome (alcoholism) or alzheimers?

Answer 44

Patients with Korsakoff’s syndrome or Alzheimer’s have greatly reduced REM sleep.

Question 45

How does REM sleep contribute to memory?

Answer 45

Subjects deprived of REM sleep show significant impairment of memory consolidation for complex cognitive tasks. Dreaming may enable memory consolidation, reinforce weak circuits.