Theme 7: Consolidation and forgetting

Question 1

Wixted 2007: comparing power low and exponential function

Answer 1

equations both fit very well, –> predictive value? –> exponential is less accurate (overestimating memory) –> power law makes good predictive functions

Question 2

exponential function; asymptote = 0

Answer 2

assumes constant rate of forgetting

Question 3

two types of interference

Answer 3

-consolidation account: new memories interfere with memories that havent ben properly consolidated yet
-cue-overload account: too many concepts become associated with the same cue

Question 4

retroactive interference

Answer 4

encoding of new information interferes more with recently formed memories than with older memories

Question 5

what does wixted argue about interference

Answer 5

there is a failure to distinguish between interference based on trace degradation (storage phenomenon) and interference based on cue overload (retrieval phenomenon)

Question 6

retrograde facilitation

Answer 6

material learned just prior to taking alcohol/benzos is remembered than it otherwise would have been (because drugs protect those memories from retroactive interference by not being able to form new memories)

Question 7

cause of retrograde facilitation through drugs

Answer 7

1) drugs close hippocampus to new input –> anterograde amnesia without compromising consolidation of previously formed memories
2) Substances block the induction of LTP without impairing the maintenance of previously established LTP

Question 8

stability plasticity dilemma

Answer 8

how does the human brain learn new information while not overwriting previously stored memories?

Question 9

unique to sleep consolidation/active hypothesis

Answer 9

consolidation of declarative memories depends on neural mechanisms unique to short wave sleep

Question 10

opportunistic consolidation hypothesis

Answer 10

-a state of reduced retroactive interference is what favours both cellular and systems consolidation, not sleep per se
-period of reduced interference must occur shortly after memory is encoded to initiate cellular and systems consolidation

Question 11

Tracelink model by Murre

Answer 11

3 subsystems:
- trace system (neo cortex)
- modulatory system
- link sustem hippocampus

Question 12

the double role of the hippocampus in the trace link system

Answer 12

1) scaffold, linking new memories in the cortex together
2) control centre for plasticity through LTP/greater plasticity

Question 13

strengthening/weakening of connections in the trace link model

Answer 13

-strengthening: both post and presynaptic neurons are active
-weakening: postsynaptic neurons is active but presynaptic neuron is not

Question 14

how lesions affect learning in trace link model:

Answer 14

–hippocampus/link system: old memories are preserved better than new ones because they’ve had more consolidation (robots gradient)
–modulatory system: no learning/encoding in hippocampus
–neocortex/trace system: if system is lesioned completely –> dysfunctional model, if only connectivity is reduced –> system solely dependent on hippocampus so normal forgetting curve or inverse Ribot’s gradient

Question 15

two assumptions of trace link model:

Answer 15

1) implicit memory gradient in retrograde amnesia: no implicit memories for recent memories, but yes priming for intermediate and remote memories (due to partial consolidation)
2) severe lesions to neocortex will halt consolidation –> steeper forgetting curve/inverse ribots gradient

Question 16

causes of recovery from retrograde amnesia in trace link model:

Answer 16

• reversible lesions
• actual repair of connections

Question 17

main thing distinguishing trace link from other model

Answer 17

double role of hippocampus; also important for cortical plasticity