functions of sleep 2 Flashcards
cognitive functions of sleep
· Memory
· Reflexes
· Attention
· Mood - preferentially notice things that are threatening
· Emotional reactivity
Emotion
causes of chronic sleep deprivation
sleep disorder, modern work schedules, lifestyle (e.g. netflix)
effects of chronic sleep deprivation
sleepiness, mood (mood enhancement, mania, or bad mood), impaired cognitive performance - driving safety, chronic disease exacerbation, cardiovascular disease, diabetes
All systems in the body seem to responsive to sleep deprivation - all these things look like stress response
randy gardner - effects of acute sleep deprivation
· Stanford student who spent 11 days 25 min awake
· Cognitive symptoms (slow reaction time, forgetfulness, inattention) turned into psychiatric symptoms
· 4-5 days = “waking dreams” (hallucinations): decreased alertness, possibly microsleep
· Transient paranoia, Suspiciousness, resentment
· Fleeting disorientation in time
· Body sensations: burning eyes, heaviness, fatigue
· Mornings were the hardest
randy gardner: recovery sleep
Once he went to bed, he was fine. His sleep looked:
- Relatively normal - only 14 hours and 40 minutes
- First recovery night - rem sleep suffered
Next night back to normal
sleep and memory
· We sleep to forget and we sleep to remember
Sleep helps consolidate memories:
· You learn better after having slept
· You remember better after a night (or even a nap!) of sleep
Sleep….
· Gradually extracts the meaning of experiences, the gist
· Create associations with previously learned material
memory by duration
▪ Sensory memory (milliseconds 1-2 sec)
▪ Short term memory buffer - few dozen seconds, needs conscious effort
Long term - days, months, years - relatively stable in brain
declarative (explicit) and non declarative (implicit)
Declarative memories get separated into:
▪ Episodic - personally experienced events, spatial and temporal memory features - mental time travel
▪ Semantic - facts and concepts about the world
Nondeclarative memories get separated into:
▪ Skills and habits - “how to”: ride a bike, language, perceptual motor and cognitive abilities
▪ Priming - processing facilitation after prior exposure
Conditioning - elementary associative memory
EPISODIC:
· Mental time travel - trade off is trauma
· What where when
· Importance of context
· Unique to primates? (maybe who knows? 🐬 or 🐒 )
· Autobiographic memory
· Same networks used to imagine the future
Both accessible to consciousness
SEMANTIC:
· Facts and concepts
General knowledge of the world
IMPLICIT/NON DECLARATIVE MEMORY
.not generally accessible to consciousness
Procedural memory: - how to do things like riding a bike, write, play a musical instrument
Conditioning and priming
HIPPOCAMPUS AND AMYGDALA
· Amygdala plays a role in strong emotional memories
Interacts with the hippocampus, which is more involved in the factual or contextual aspects of memory
long term potentiation
· Long term potentiation
· HEBB: neurons that wire together, fire together
Before repeated stimulation, there will still be a response, but after repeated stimulation there will be more receptors and neuron will be more easily stimulated
memory consolidation in animals
In animals 🐓🦀🦁🐂🐄🦐🐊🐀🐈🦬: evidence for neural replay during sleep
- Faster, slower, backwards
- Something happening during replay to stabilize memory traces
Replay is correlated with performance
memory consolidation in humans
- This replay is likely taking place via involvement of the hippocampus
- What is the role of mental activity in sleep? Do dreams reflect memory consolidation?
memory consolidation in general
· A temporal process of transfer and triage /filtering of newly encoding information
· Takes many days for something to be fully transferred into long term storage
Has daytime and nighttime components
HOW DO WE STUDY THE ROLE OF SLEEP IN MEMORY CONSOLIDATION?
Three main methods:
- Observational: look for correlates (e.g. sleep stage %, sleep microarchitecture, etc. after learning)
- Sleep deprivation of selective sleep stage deprivation
Targeted memory reactivation
SOME OF THE MAIN MODELS OF SLEEP DEPENDENT MEMORY:
○ Sleep protects memory from forgetting
○ REM sleep is for memory consolidation
○ Sleep facilitates forgetting
○ Dual process
○ Sequential process
- Active systems consolidation
REM SLEEP AND MEMORY CONSOLIDATION
· Association between REM sleep and dreaming - does REM sleep have anything to do with memory
· REM sleep increases after learning in animals
· REM deprivation in animals - impaired learning of complex tasks
· More recent work: REM sleep may be preferentially involved in procedural learning (and likely learning with emotional component)
classic view of sleep stages and memory consolidation
· Sws: strengthens declarative, semantic learning (word-pairs, for exampls)
· REM: improves procedural learning (mirror tracing, finger tapping) but also emotional learning
However: sleep spindles, rapid eye movements, may occur both early and late
SEQUENTIAL HYPOTHESIS OF SLEEP DEPENDENT MEMORY CONSOLIDATION
- Not just sws/rem, but cyclic succession or intact overall sleep architecture is important for memory consolidation
- Sws: strengthens connections between new engrams (neural substrate for storing memories - hypothetical means by which information is stored)
- Then, rem integrates these newly learned memories into larger autobiographical networks
Balance: stability vs. flexibility of the cognitive system
