Cognition and sleep

Question 1

What are the theories of sleep?

Answer 1

• All animals sleep (even though it’s dangerous!)
• Three dominant theories. Sleep is for: cellular restoration (allow cells to replenish), energy conservation, consolidation of memory and learning.
• Different sleeping patterns

Question 2

What did Yoo et al (2007) investigate looking at sleep and memory?

Answer 2

• Yoo et al. (2007): sleep deprivation before learning
• Encoding in fMRI scanner involved memorising pictures. Test involved discriminating studied pictures from unstudied pictures.
• Normal sleep vs sleep deprivation
• Asked to learn new information after two days, then 2 days after encoding everyone can sleep as normal then retested

Question 3

What did Yoo et al (2007) find looking at sleep and memory?

Answer 3

• Lack of prior sleep compromises learning and hippocampal activation during learning
• Controls remembered around 85%, no sleep deprived
• Sleep deprived remembered around 75%
• Looked at the hippocampus during encoding – sleep deprived showed less hippocampal activity

Question 4

What did Gais et al (2007) investigate looking at sleep and memory?

Answer 4

• sleep deprivation after learning
• Encoding involved memorising word-pairs. Test involved recalling the words-pairs. fMRI measured during encoding and all tests.
• Asked to encode after day 1, afterwards sleep deprivation group is deprived of sleep before they are retested

Question 5

What did Gais et al (2007) find looking at sleep and memory?

Answer 5

• Sleep deprived group forget more words
• Hippocampus works less in the sleep deprived group
• Lack of sleep immediately after learning increases forgetting and compromises hippocampal activation during later retrieval
• Lack of sleep immediately after learning leads to long-lasting (permanent?) changes in memory representations in brain areas responsible for long-term storage of memories.
• Medial prefrontal cortex works harder in retrieval for those in the control condition

Question 6

What are the stages of sleep?

Answer 6

• Sleep stages: Stage 1 (when you first go to sleep, half way between awake and asleep) , Stage 2 (deep sleep), Slow-wave sleep (Stages 3 + 4)
• Rapid eye-movement sleep (REM)

Question 7

What did Walker et al. (2002) investigate looking at motor learning and sleep?

Answer 7

• Procedural memory
• Sequential finger tapping task on non-dominant hand – tap buttons in a certain sequence as quick as you can
• 10am (train – wake – test – sleep – test) vs 10pm (train – sleep – test – wake – test)
• AM/PM design to tease apart benefits of time spent awake vs. sleep

Question 8

What did Walker et al. (2002) find looking at motor learning and sleep?

Answer 8

• Sequential finger tapping task on non-dominant hand
• 10am group: improve slightly from 10am to 10pm testing (day of wakefulness) – following day (after sleep) major improvement
• 10pm group: significant improvements from first testing to second testing after sleep
• Stage 2 sleep improve memory – not found with any other stages

Question 9

What did Monaghan et al. (2015) investigate looking at sleep and problem solving?

Answer 9

• Analogical problem solving
• Morning vs evening test group
• Example of a source problem: General attacking a fortress with mines on the road.
• Example of a target problem: How to target a stomach tumour with a ray that destroys healthy tissue.
• See the problem solving lecture for details of these problems!

Question 10

What did Monaghan et al. (2015) find looking at sleep and problem solving?

Answer 10

• Sleep group (evening condition) did significantly better in the target problem
• No difference in sleep for source problems
• Solution accuracy also correlated with sleep duration. More sleep = more accurate solutions to target problems. Sleep facilitates transfer of old solutions to new problems.

Question 11

What did - Wagner et al. (2004) investigate looking at sleep and insight?

Answer 11

• Number reduction task
• Associated with problems where you cannot describe the solution in words very effectively, suddenly realise the solution
• Insight: This number is always the same as the solution number!

Question 12

What did - Wagner et al. (2004) find` looking at sleep and insight?

Answer 12

• Sleep group, wake (night group) and wake (day group)

- The number of participants who gained the insight was largest in the sleep group.

Question 13

What was Wagner et al (2004) – 2nd analysis ?

Answer 13

• Let’s look at the sleep group only and let’s look at the participants who gained insight (solvers) and participants who didn’t gain insight (non-solvers) separately.
• How did task performance change overnight in solvers and nonsolvers?
• In solvers, sleep had no impact on the reaction times (RTs) in the task. In non-solvers sleep made RTs significantly faster!
• Sleep promoted insight in solvers and facilitated calculations in non-solvers. Why does sleep have a different impact on different people in this task?

Question 14

What did Ellenbogen et al. (2007) investigate looking at sleep and reasoning?

Answer 14

• Inferential knowledge
• Asked to look at coloured patterns with certain rules
• Premise pairs: A > B B > C C > D D > E E > F
• Embedded hierarchy: A > B > C > D > E > F
• Inference pairs: Is B > D? (1 degree of separation) Is C > E? (1 degree of separation) Is B > E? (2 degrees of separation)

Question 15

What did Ellenbogen et al. (2007) find looking at sleep and reasoning?

Answer 15

• Wake group, sleep group and 24h delay group
• Sleep and wake have similar impact on close inference pairs.
• But a night of sleep boosted performance on distant (2 degrees of separation) inference pairs.
• Sleep did better than wake group

Question 16

What did Payne et al. (2009) investigate looking at sleep and false memories?

Answer 16

• Deese-Roediger-McDermott (DRM) task
• Morning and evening group
• At study: Memorise 12 DRM lists.
• At test: Free recall of as many words as possible.
• Time-of-day control groups studies in the morning or in the evening and were tested (almost) immediately.

Question 17

What did Payne et al. (2009) find looking at sleep and false memories?

Answer 17

• True memories: sleep group remembered more words than wake group
• False memories: sleep group remembered more false memories than wake group

Question 18

Mechanisms of consolidation?

Answer 18

• Saletin & Walker (2012, adapted from Frankland & Bontempi, 2005)
• A: (WAKE) Hippocampus rapidly encodes new information and integrates it in distributed cortical networks
• B: (SLEEP) Hippocampal information repeatedly reactivated during sleep -> gradually strengthens cortico-cortical connections
• C: (WAKE) Reactivation over time integrates new memories with cortical memories

Question 19

How did - Rasch et al. (2007) investigate reactivation during sleep?

Answer 19

Learning object locations

• Certain smell released when learning a task
• When they go to sleep, odour given again (smell condition) or no smell (no smell condition)

Question 20

What did Rasch et al find?

Answer 20

• Odour during learning and sleep – higher recall than no odour
• Odour during learning and rapid eye movements – not a significant difference compared to control condition

Question 21

Hu et al. (2015)

-Reducing social bias during a daytime nap

Answer 21

• IAT = implicit association test
• IAT on gender and racial bias
• Counterbias training on gender (with Sound 1) and race (with Sound 2)
• 90-minute nap with Sound 1 OR Sound 2 played during SWS
• IAT on gender and racial bias
• IAT on gender and racial bias one week later

Question 22

Hu et al. (2015)

-Reducing social bias during a daytime nap (findings)

Answer 22

• Counterbias training was initially successful in reducing both types of bias.
• Cueing (playing the associated sound during sleep) further reduced bias!
• Without cueing during sleep, bias returns to baseline. Cueing maintains the counterbias training effect!

Question 23

Hall (1972) found that people tend to dream about their waking experience:

Answer 23

• “A large number of dreams reflected faithfully the daytime activities and preoccupations of the dreamer. Skiers dream of skiing, surfers dream of surfing, and mountain climbers dream of climbing mountains. Teachers dream of classroom situations, bankers dream of banking activities, and nurses dream about their patients.”
• Hall was able to create accurate profiles and histories of psychiatric patients just by reading large numbers of their dream reports!

Question 24

Wamsley et al. (2010): Dreaming enhances consolidation

Answer 24

• Dreaming may reflect spontaneous reactivation, and the brain integrating new memories with old memories.
• Train on a maze navigation task, then take a nap or stay awake. Everyone asked 3 times to report what they were dreaming about or thinking about during sleep/wake. Re-test on maze task later in the day.

Question 25

Wamsley et al. (2010): Dreaming enhances consolidation - findings

Answer 25

• Sleep group improved during the nap. Wake group did not.
• Those sleepers who reported dreaming about the maze improved significantly during the nap. Sleepers who did not dream about the maze did not improve.