function and emotions in sleep Flashcards
active systems consolidation
a system for consolidating new memories/moving memories into long term storage during sleep
the hippocampus creates temporary binding connections between different memory traces in the neocortex - over time, as the hippocampus replays memory traces during sleep, they become independent of the hippocampus
what are the main EEG characteristics thought to play a major role in the hippocampal neocortical dialogue
- slow waves (neocortex)
- sharp waves/ripples (hippocampus)
- spindles
why do we call it ‘active’ systems consolidation
because every time we replay a memory it changes
active systems consolidation is a process through which memories are:
- replayed
- potentiated
- transformed
which neural oscillations predict learning in which stages of sleep?
n2 and 3 (sws) : spindles predict learning
rem: theta, alpha, high beta predict learning - delta predicts learning in all stages
what affects the consolidation of memories during sleep?
sleep doesn’t consolidate all information uniformly:
consolidation is influenced by:
- context
- goals
- motivations
- salience
- emotional stuff - more emotional, more likely to remember
how does sleep extract the gist of new experiences?
one role of sleep isn’t the strengthening of individual memory items, but their abstracted assimilation into a schema of generalized knowledge - reorganizes what we’ve learnt
- selective consolidation - things learned during the day are tagged as either relevant or irrelevant (irrelevant stuff is weeded out)
- item integration - newly learned things are integrated into general knowledge
- multi item integration - we can use the pool of general knowledge to extract the gist of a memory, extrapolate rules about the general group, and construct false memories
hippocampal neocortical dialogue in memory
idea that information initially requires binding by the hippocampus. Over time, during sleep, the hippocampus reactivates the networks that correspond to that information/memory and gradually strengthens the connections between neocortical sites involved in the memory, eventually allowing the original information to be activated independent of the hippocampus. Blocking sleep, doesn’t allow this transfer, decreasing the capacity for new hippocampal learning the next day
synaptic homeostasis hypothesis
encoding during wakefulness induces a global upscaling of glutamatergic synapses in cortical and subcortical structures (including hippocampus) - in sleep, average connectivity in these networks is downscaled to baseline levels to prevent and accumulation of upscaling that would lead to excessive energy and space demands (important things can also be upscaled)
- this leaves room to learn new things the next day!
why is sleep an affective blanket
we remember the stuff that was more emotional but rem sleep consolidates and integrates emotional memory while decoupling it from the emotion that initially ‘tagged’ it for memory, thus reducing anxiety when reactivated
means that less amygdala and adrenergic activity when memory is reactivated after sleeop
ptsd
able to remember things exactly as they happened, and nightmares that replay episodes (this stuff never happens normally)
….most of what we know on emotional disassociation of memory is from ptsd - take the pathological example and reverse engineer what should actually happen
memories never got decoupled from emotion and amygdala still has a strong effect
what happens to our emotions when we are sleep deprived
we have a stronger emotional response to everything since the amygdala is more involved in memory consolidation
this happens because when we don’t get enough sleep, the prefrontal cortex has a weaker connection to the amygdala and is less effective at dampening its response
vicious cycle of sleep and anxiety
Anxious = harder time falling asleep= sleeping poorly = more amygdala= more anxious = less sleep
Lessen anxiety = improve sleep, improve sleep = lessen anxiety
….could be seen as multiple sites of intervention? Or just a circle of doom…
activation of the amygdala following sleep deprivation
- Threat perception is enhanced
- Neutral stuff is perceived as threatening
So…we are still able to perceive threats, but brain activity is magnified…so we are more sensitive over all
- Neutral stuff is perceived as threatening
memory replay in rem sleep
Possible that there is a replay of different memories in rem and nrem - rem associated with procedural, implicit learning
- Found that after procedural task, same regions were activated in rem
- Predict post sleep task improvement
targeted memory reactivation in sleep (tmr)
Idea: triggering memory replays during sleep
Tmr: replay of sensory cues during sleep that were previously associated with learning
Rat studies 🐀: 1985: hars et al, electric shocks in wake followed by same shocks in rem sleep = better performance
Human studies:
1989 (geurrien et al): auditory stimulation in phasic rem sleep - improvement on a morse code learning task
1990 (smith et al): clock sound during phasic rem sleep - improvement on a complex logic task
odors and memory consolidation in sleep
- Odor paired with learning procedure, then re-exposure during sleep
- Does sleep increase learning preferentially when paired with cued odor
- Odor + sws = improves declarative memory —-hippocampus
- Odor + rem does not
Odo + procedural memory - no improvement
TMR could be used to enhance…..
· Declarative memory
· Language
· Procedural memory
· Emotional memory
· Spatial memory
· Social bias
Sleep therapies
POSSIBLE APPLICATIONS OF TMR
Procedural memory:
→ Physical rehabilitation (after stroke, injuries)
→ Athletic development
→ Musical performance
Declarative memory:
→ Memory impairment (aging neurodegenerative diseases,…)
→ Learning disabilities
Learn a new language
can restful wakefulness enhance memory
yes - ex. meditation
VERBAL CUEING:
- Can boost vocabulary learning by verbal cueing during sleep
Cueing prior learned foreign vocabulary during sleep improved later recall
PROCEDURAL MEMORY
Skill learning study:
1. Learn two memories on the keyboard
2. One of the two melodies is replayed during nrem sleep
In the morning, the participants played the cued melody more accurately than the non cued melody
TMR TO FORGET (MEMORY EXTINCTION?)
To diminish effects of trauma? Ptsd?
→ Auditory fear conditioning paradigm (mild electric shock paired with a sound)
→ Measure of fear: skin conductance (sweater)
→ Fear response was lowered when auditory stimulus was presented in wake or in slow wave sleep
→ Sleep ‘therapies’?
How does it work?
Looks like if you cue a participant, hippocampus re activates the cortical representations through theta and gamma activity - spindles are then necessary to stabilize and strengthen these representations
Olfactory TMR
nostrils only go towards one hemisphere
Tmr has a local effect:
Improved memory for specific words processed in the cued hemisphere - tmr modulates local slow wave activity and sleep spindles (more synchronized)
insomnia prevalence.
…women tend to experience more insomnia - not clear what percent of the population
Rates increase as you age
definition of insomnia
….for something to qualify as insomnia, it shouldn’t necessarily have an organic cause (like drinking coffee)
Has to be about:
· Difficulty initiating sleep
· Difficulty maintaining sleep, characterized by frequent awakening or problems returning to sleep after awakenings
· Early morning awakening with inability to return to sleep
In order for something to qualify as insomnia, it cannot be transient
three categorizies for defning incolmnia
· Sleep difficulty occurs at least 3 nights per week
· The sleep difficulty is present for at least 3 months
The sleep disturbance causes clinically significant distress of impairment in social, occupational, educational, academic, behavioural, or other important areas of functioning
other prerequistes for insomnia diagnosis
· The sleep difficulty occurs despite adequate opportunity for sleep (can’t just be sleep deprived)
· Cannot be explained by or does not occur exclusively during the course of another sleep wake disorder - (narcolepsy, breathing related sleep disorder, parasomnia, etc)
· Insomnia is not attributable to the physiological effects of a substance
Coexisting mental. Disorders and medical conditions do not adequately explain the predominant complaint of insomnia
cost of insomnia in the world
→ Total annual cost of insomnia in quebec = 6.6 billion
Average annual per person costs for insomniacs = 5010 and 1431 for people presenting with symptoms
insomnia and mental health
Sleep as an enhancer for things you already have…what are you more susceptible to ?
- An amplifying factor for underlying conditions
- Directionality = unclear
COMORBIDITY: anxiety, suicidal ideation, depression
Even just dealing with sleep can greatly improve symptoms of these disorders ^^^ “if you fix sleep, every other thing will be easier to deal with”
pharmacological treatments for insomnia
→ Sleeping pills = not great, tons of side effects, associated with neurodegeneration down the line
→ Typically benzodiazepines or similar (Z-drugs)
→ Effective for shortening sleep onset and maintaining sleep
→ Not to be used for more than 4-16 weeks
→ Tolerance, addiction and withdrawal symptoms are serious problems - problem with all psychiatric disorders is that we don’t really know how to de prescribe
→ Side effects: day time fatigue, motor vehicle crashes, accidents, cognitive impairments, falls, fractures, old people more sensitive
Associated with cognitive decline in old people, including alzheimer dementia
melatonin
→ Orally, has sleep enhancing and circadian rhythm modifying effects
→ Data suggests that melatonin has therapeutic effect on sleep onset that is greater and more consistent than its effects on the ability to stay asleep or the duration of sleep
→ No substantive risks of melatonin has been identified
→ Most commonly reported side effect is headache
→ Suggests that higher melatonin levels may be associated with reversible inhibition of spermatogenesis and ovulation
→ Abuse potential = minimal
Missing longitudinal data and large scale studies
cognitive behavioural therapy for insomnia
Most effective….multimodal intervention combining some of the above cognitive behaviour )e.g. stimulus control, sleep restriction, relaxation) procedures
Big commitment = 5 to 8 sessions
sleep restriction cbt
▪ Time in bed restricted as close as possible to the actual sleep time
▪ Strengthening homeostatic sleep drive
▪ Sleep window is then gradually increased over a period of a few days or weeks until optimal sleep duration is achieved
stimulus control cbt
A set of instructions designed to reinforce the association between the bed and bedroom between the bed and bedroom with sleep and to reestablish a consistent sleep-wake schedule
▪ Go to bed only when sleepy
▪ Get out of bed when you can’t sleep
▪ Use the bed/bedroom for sleep only (no reading, watching tv, etc)
▪ Arise at same time every morning
No napping
relaxation control cbt
Clinical procedures (e.g., progressive muscle relaxation) aimed at reducing autonomic arousal, muscle tension, and intrusive thoughts interfering with sleep - most relaxation procedures require some professional guidance initially and daily practice over a period of a few weeks
cognitive therapy
Psychological approach using socratic questioning and behavioural experiments to reduce excessive worrying about sleep and reframe unhelpful beliefs about insomnia and its daytime consequences
Additional cognitive strategies may involve paradoxical intention technique to alleviate performance anxiety associate with the attempt to fall asleep
sleep hygiene education
…general guidelines about health practices
▪ Diet
▪ Excercise
▪ Substance use
▪ Environmental factors (light, noise, excessive temp
Basic info about normal sleep and changes in sleep patterns with aging
cbti efficiency
→ Efficient for a broad range of patients - including those with comorbid psychiatric conditions such as depression, bipolar disorder, posttraumatic stress disorder and schizophrenia
→ Reduced depression severity
→ Higher remission rates
→ Reduced anxiety
Reduced suicidal ideation
cbti vs pharmocological treatment
· More efficient
· Addresses the root causes of insomnia (pharmacological treatments don’t)
· But takes several weeks to complete and demands considerable effort - pill is easy and immediate
Super important you complete the 5-8 weeks - bc its hard to restart if you strop out
stepped care model for delivery of cbt
- Start with an app
- If it doesn’t work, do it in a group (cheaper)
- If that still doesn’t work, move up to graduate psychologist
- Then really tailored to you - clincal psychologist
Then super specialized - behavioural sleep specialist
THEORIES OF INSOMNIA:
HYPERAROUSAL AND STRESS REGULATION:
· HPA axis reactivity
· Cortisol dysregulation
· Affective reactivity
· Sleep reactivity - a potential trait
Reaction to allostatic load
SLEEP STATE MISPERCEPTION/PARADOXICAL INSOMNIA
….some people, particularly insomniacs, report a different between how much they think they’ve slept and how much they’ve actually slept
- Moon, Song, and Cho 2015 - estimated that 26.4% of insomniacs underestimated how much they slept (less then 6.5 hours, sleep efficiency >85%)
- Associated with high levels of distress and anxiety associated with perceived lack of sleep
Can be positive (overestimating) but pretty rare
SLEEP STATE MISPERCEPTIONA AND INSOMNIA
- Insomniacs always underestimate how much they’ve slept and overestimate how long it takes them to fall asleep
- But are pretty accurate/underestimate how much they wake up
- Good sleepers tend to overestimate how much they’ve slept, are pretty accurate over all - but underestimate how much they wake up
….but connection between cortical arousal and sleep state misperception!!
