7 sleep and memory consolidation

Question 1

What are the three models of memory consolidation

Answer 1

1. Dual process model
2. two step model
3. active systems consolidation model

Question 2

dual process model:

Answer 2

Ackerman and Rasch (2014)
SWS = declarative memories.
REM sleep= non declarative memories.
Stage 2= motor tasks.

Due to circadian rhythm the ratio of SWS is higher in the first part of the night. The dual process model proposes that declarative memories are associated with SWS and non declarative with REM sleep.

Question 3

Limitations of the dual process model

Answer 3

1. Ignores the contribution of stage 2 sleep to memory

2. memories which have a declarative and non declarative part.

Question 4

The two step model

Answer 4

1. non adaptive memories are weakened during SWS

2. adaptove memories are integrated in REM sleep.

Question 5

Eval of two step:
Strengths
Weakness

Answer 5

+

• Supported by animal and human evidence
• sleep stages are not viewed in isolation
• cyclic structure of sleep is important.
• difficult to test directly
• what are the functions o exact stage

Question 6

Active system consolidation model

Answer 6

When memories are first encoded they are encoded both into the hippocampus and the neocortex.
When a memory has undergone little consolidation the hippocampus via hippocampal neocortical connections binds together these highly distributed memory nodules in order to bring a coherent representation to consciousness.

Slow oscillations are thought to drive a reactivation of memory in both the hippocampus and neocortex. This leads to weakening of hippocampal neocortical connections and strengthening of cross cortical connections.

When complete the memory is no longer dependent on the hippocampus and entirely dependent on neocortex.

Question 7

Active system consolidation model

- Born et al (2012)

Answer 7

When memories are first encoded they are encoded both into the hippocampus and the neocortex.
When a memory has undergone little consolidation the hippocampus via hippocampal neocortical connections binds together these highly distributed memory nodules in order to bring a coherent representation to consciousness.

Slow oscillations are thought to drive a reactivation of memory in both the hippocampus and neocortex. This leads to weakening of hippocampal neocortical connections and strengthening of cross cortical connections.

When complete the memory is no longer dependent on the hippocampus and entirely dependent on neocortex.

Question 8

Targeted memory reactivation - smell

Answer 8

Rasche et al (2007)
pps learnt card locations + smell of rose.
During SWS - smell = significantly better memory.
NOT REM. or odor only during SWS,

Same study - fMRI:
lit us hippocampus.

Question 9

Active system consolidation model

- Born et al (2012)

Answer 9

When memories are first encoded they are encoded both into the hippocampus and the neocortex.
When a memory has undergone little consolidation the hippocampus via hippocampal neocortical connections binds together these highly distributed memory nodules in order to bring a coherent representation to consciousness.

Slow oscillations are thought to drive a reactivation of memory in both the hippocampus and neocortex. This leads to weakening of hippocampal neocortical connections and strengthening of cross cortical connections.

When complete the memory is no longer dependent on the hippocampus and entirely dependent on neocortex.

Question 10

Targeted memory reactivation- Sounds

Answer 10

Rudoy et al (2009)
50 objects accompanied by specific sounds.
During SWS 25 sounds replayed. Significantly better.

Question 11

Sleep memory and age.

Answer 11

Carskadon and Rechtschaffen (2005)

Sleep architecture changes as we age. Decrease in SWS. - connected to memory decline ?

Question 12

Reasons for loss of SWS with age

Answer 12

• change in internal clock
• degeneration of frontal cortex
• comorbidities
• side effects of medications
• need to urinate more frequently
• pain
• stimulants such as nicotine and caffeine

Question 13

How does lack of SWS affect memory?

Answer 13

Helfrich et al (2018)
SWS is important for memory consolidation. IN young healthy adults the brain wavees associated with SWS are synchronised.
- this synch helps consolidation of memories
- the slow wave oscillation in line with spindle
- With age SWS no longer synch
- the sleep spindle not in line.
- size of the wave will be smaler- because fewer neurons firing at the same time.