Week 8 - The biological basis of memory

Question 1

What is memory?

Answer 1

The ability to encode, store, and retrieve information. There are many different forms of memory that are separable, (one can be damaged leaving another intact.

Question 2

What did Hebb (1949) think in regards to memory?

Answer 2

It is unlikely that there is a chemical process quick enough to account for immediate memory, but stable enough to provide permanent memory, so proposed a distinction between short-term and long-term memory.

Question 3

What is “implicit” memory?

Answer 3

Learning that takes place without our awareness.

Question 4

What is the Striatum?

Answer 4

made up of the caudate and the putamen, often correlated to reaction time. Individuals with injury in the area (such as parkinsons) tend to do poorly on implicit memory tasks.

Question 5

medial temporal lobe (MTL) is crucial for what type of memory?

Answer 5

declarative memory (episodic, autobiographical, semantic).

Question 6

What is consolidation?

Answer 6

Occurs in the hippocampus, where short term memories are converted into long term memory.

Question 7

Consolidation is affected by a variety of factors such as…

Answer 7

The depth of stimulus processing, distinctiveness, relevance, emotionality.

Question 8

Explain emotional memory.

Answer 8

Stressful or emotionally exciting experiences increase the secretion of adrenaline (aka epinephrine) and cortisol Small to moderate amounts of cortisol activate the amygdala and hippocampus where they increase memory consolidation and storage. The amygdala stimulates the hippocampus and cerebral cortex which increases memory storage.

Question 9

How does prolonged stress impact memory?

Answer 9

It impairs memory due to the large increase in cortisol amounts.

Question 10

What is re-consolidation?

Answer 10

When a memory is reactivated (retrieved/remembered), it is brought into a labile state, In this labile state it is fragile, or malleable, it can be weakened or altered, or it can be strengthened.

Question 11

Hebb (1904-1985) suggested that a specific axon repetitively stimulating another would…

Answer 11

lead to growth or metabolic change that would connect them more strongly, this early suggestion of memory formation appears to be quite accurate.

Question 12

How are memories created?

Answer 12

due to changes happening at synapses between neurons of the hippocampus. These changes occur when one or more axons bombard a dendrite with stimulation.

Question 13

What is Long Term Potentiation (LTP)?

Answer 13

In the process of memories being created, the repeated stimulation leaves the synapse “potentiated” for a period of time, meaning it is more responsive.

Question 14

What is the most prevalent excitatory neurotransmitter in the brain?

Answer 14

Glutamate.

Question 15

What two types of glutamate receptors are important in LTP?

Answer 15

AMPA and NMDA. These are ionotropic receptors because when they are stimulated, they open channels for ions to pass through.

Question 16

What is AMPA?

Answer 16

Important to LTP, a typical ionotropic receptor that opens sodium channels (Na+) when stimulated by glutamate.

Question 17

What is NMDA?

Answer 17

Important to LTP, NMDA’s response to glutamate depends on the polarity of the membrane (the membrane potential) – sodium can’t come in until it is depolarized.

Question 18

What are the properties of LTP?

Answer 18

Specificity: only synapses onto a cell that has been highly active become strengthened.
Cooperativity: simultaneous stimulation by two or more axons produces LTP much more strongly than does repeated stimulation by a single axon.
Associativity: pairing a weak input with a strong input enhances later responses to a weak input.

Question 19

What is long term depression (LTD)?

Answer 19

Opposite of LTP. A prolonged decrease in response at a synapse occurs for axons that have been less active than others.

Question 20

What types of memory are improved by sleep?

Answer 20

Both declarative and procedural.

Question 21

How does sleep affect procedure memory?

Answer 21

procedural abilities are optimised. It is suggested that the spontaneous (re)activation of memory traces during sleep operates as a form of supplementary training, triggering long-lasting changes in performance.

Question 22

How does sleep affect declarative memory?

Answer 22

Sleep protects newly learned declarative memories from interference.
The beneficial effects of sleep are enhanced if sleep takes place immediately after learning rather than after a delay.

Question 23

Sleep deprivation has been associated with what?

Answer 23

explicit learning and memory problems may be due to its effects on the hippocampus. Sleep appears to have a big influence on LTP, although the exact mechanisms of sleep’s contribution to memory consolidation is not yet known.

Question 24

How does exercise impact declarative memory?

Answer 24

Improves it, likely due to increase in BDNF.

Question 25

What is directed forgetting?

Answer 25

A phenomenon involving impaired long-term memory triggered by instructions to forget information that has been presented for learning. It allows us to see how we can intentionally control our memory, to look at neural differences in responding to intentionally compared to unintentionally forgotten material.

Question 26

What are the two phases of directed forgetting?

Answer 26

Study Phase: Participants are shown a series of words or pictures which they are instructed to either remember or forget.
Test Phase: Participants are tested on their recognition of study words (indicate whether a word or picture is old or new) or their free recall of the study words.

Question 27

What are the two possible explanations for directed forgetting?

Answer 27

Selective rehearsal and active suppression.

Question 28

What is selective rehearsal?

Answer 28

TBR items are subjected to more elaborative processing and more repeated rehearsal than items instructed to be forgotten. TBR memory traces are strengthened, while TBR traces are more likely to passively decay (Basden, 1993).

Question 29

What is active suppression?

Answer 29

TBF instruction leads to the recruitment of inhibitory mechanisms which terminate further processing of TBF items and suppress their memory to below-baseline levels (Levy & Anderson, 2002).

Question 30

What are Event-Related Potentials (ERPs)?

Answer 30

a measure of electroencephalography (EEG).

Question 31

How is the process of forgetting different for emotional memories?

Answer 31

They found that there was a significant DFE for neutral photos, but the DFE disappeared for negative photos. This shows that negative information is harder to forget than neutral information.

Question 32

Hauswald et al’s ERPs suggest that negative information is immune to directed forgetting because…

Answer 32

Negative images are processed more deeply than neutral (increased parietal positivity in response to the negative picture).
Suppression of the memory trace is less successful (decreased frontal positivity in response to the forget cue in the negative condition).

Question 33

the neural mechanism underlying explicit memory creation is known as what?

Answer 33

Long term potential.

Question 34

Long-term memories are created by changes at the synapses in the:

Answer 34

hippocampus.

Question 35

LTP depends on changes at which two glutamate receptors?

Answer 35

AMPA and NMDA.

Question 36

What might happen to the presynaptic neuron as a result of LTP?

Answer 36

decrease in action potential threshold
increased neurotransmitter release
expansion of the axons

Question 37

the directed forgetting effect is suggested to occur due to:

Answer 37

selective retrieval of to-be-remembered items AND active suppression of to-be-forgotten items

Question 38

Hauswald et al (2011) conducted a directed forgetting task using negative and neutral pictures. Their results suggested that:

Answer 38

negative pictures are harder to forget than neutral pictures.

Question 39

Implicit memory refers to:

Answer 39

unintentional, nonconscious memories.

Question 40

Following extensive brain surgery, patient H.M suffered from what condition?

Answer 40

anterograde amnesia

Question 41

Implicit sequence learning is thought to be dependent on the:

Answer 41

striatum.