Memory consolidation

Question 1

Models

Answer 1

Dual process model: level 1
Two step model: level 2
Active systems consolidation model: level 3

Question 2

What does dual process model focus on?

Answer 2

Specific components of NREM & REM:
SWS helps consolidate declarative memories
REM helps with non declarative memories

Explains how different sleep stages help with different types of memory consolidation

Question 3

What does the two step model focus on?

Answer 3

NREM REM cycle
Importance of successive cycle of REM & SWS sleep stages in natural occurrence of sleep

REM: adaptive memories strengthened & integrated within existing memory networks
NREM: non adaptive memories weakened

Question 4

What does the active systems consolidation model focus on?

Answer 4

Integrates aspects of dual process & two step model

Cycle between NREM and REm is important for specific stages of sleep: for memory consolidation

Question 5

What is the dominant model?

Answer 5

Active systems consolidation model

Question 6

Describe dual process model

Answer 6

Ackermann & Rasch 2014
Tested using night paradigm: participants tested after SWS or REM sleep but not both

Due to circadian rhythm, ratio of SWS is higher in first part of night and ratio of REM is higher in second part of night

Proposes declarative memory is associated with SWS
Non declarative associated with REM

Extension of model proposes simpler tasks associated with stage 2 sleep

Question 7

Describe two step model

Answer 7

Step 1: non adaptive memories weakened during SWS and lost

Step 2: adaptive memories integrated in REM

Question 8

Strengths of two step model

Answer 8

Supported by animal and human evidence
Sleep stages not viewed in isolation
Cyclic structure of sleep is important: serves function

Question 9

Limitations of two step model

Answer 9

Difficult to test directly because cycle doesn’t say what each function of sleep stage is

Question 10

Limitation of dual process model

Answer 10

May be too simplistic: cannot say declarative is SWS and non declarative is REM

Question 11

Describe active systems consolidation model

Answer 11

Form memories via learning –> consolidation –> retrieval - targeted memory reactivation

Born et al, 2006, 2011, 2012
When memories first encoded, into hippocampus and neocortex

For a new memory: hippocampus via the hippocampal cortical connections bind together neocortical memory nodules to bring a coherent representation to consciousness

Slow ossilations drive reactivation of memory in both hippocampus and neocortex, leading to weakening of neocortical connections & strengthened cross cortical connections

Once process is completed, memory dependent on neocortex not hippocampus

Question 12

What is targeted memory reactivation

Answer 12

Can be triggered by sounds and odours
Can manipulate what you replay in sleep
Key part of active systems consolidation model

Question 13

Describe Rasch et al 2007 study

Answer 13

Participants learnt card locations
Underwent test phase to recall locations
When undergoing training, were subjected to scent of rose
In SWS presented with rose again
Had to present in both conditions to have an effect

Study was repeated with fMRI and hippocampus lit up in SWS when presented with odour

Question 14

What studies looked at targeted memory reactivation

Answer 14

Rasch et al 2007, Rudoy et al 2009

Question 15

Describe Rudoy et al 2007 study

Answer 15

Shown 50 objects with corresponding sound
25 sounds played in SWS
Sig. less memory decline for items cued by sounds during sleep

Question 16

How does age affect memory consolidation?

Answer 16

Carskadon & Rechtschaffen 2005
SWS declines sig. with age : affects memory consolidation
From age 30 onwards

Question 17

Reasons for why age affects memory consolidation

Answer 17

Changes in internal clock
Degeneration of medial frontal cortex 
Co-morbidities 
Side effects of medication
Need to urinate is more frequent 
Pain from diseases e.g. arthiritis 
Stimulants e.g. nicotine

Question 18

Describe Helfrich et al 2018

Answer 18

Young adults: brain waves in SWS are synchronised, lines up with peak of spindle

Older: no longer synchronised, so firing of neurons affects consolidation - size of wave is misaligned and smaller

Question 19

Describe Bryce & Mander study

Answer 19

Quality of sleep in older people is 75% lower than younger people

Question 20

Describe Neurbauer 1999

Answer 20

Elderly have delayed sleep onset, fragmented, early morning awakening, decreased SWS

Question 21

False memories?

Answer 21

Sleep deprivation increases formation of false memories

But can also increase formation of false memories - research is mixed and ongoing