Sleep Phys exam 1 Flashcards
(185 cards)
1
Q
What did people originally think sleep was during ancient times?
A
Soul left the body during sleep, blood retreats from the surface of the body, brain turned off
2
Q
What happened when puppies were sleep deprived during a study?
A
They died
3
Q
What happened when CSF was transferred from sleep deprived animals to undeprived animals?
A
The undeprived animals became sleepy
4
Q
What happened during the mammoth cave studies?
A
Study of circadian rhythms - caves had constant temp and can control light
5
Q
When does REM usually occur?
A
After 90 minutes of sleep
6
Q
How do we define sleep?
A
Reversible behavioral state of disengagement from and reduced responsiveness to the environment
Complex amalgam of physiological and behavioral processes
7
Q
Define polysomnography.
A
“Many writings of sleep” - a way to measure a variety of electrical activity during sleep using EEG, EOG (eye movements), EMG (muscle), respiration, and ECG
8
Q
What variables are important to measure using an EEG?
A
Speed/frequency, amplitude, morphology
9
Q
Describe awake state brain waves.
A
Faster frequency (15-35 Hz), small amplitude → β activity
10
Q
Describe drowsy state brain waves.
A
Higher amplitude than awake, slower frequency (8-12 Hz) → α activity
11
Q
Describe stage 1 of sleep brain waves.
A
Non REM, sometimes characterized by head bobs in class
Even higher amplitude than drowsy state, slower frequency (4-7 Hz) → θ activity
12
Q
Describe stage 2 brain waves.
A
Spend 50% of your time in sleep here
Contain the sleep spindle (burst of 10-14 Hz), K complex (info processing of environmental and exogenous stimuli)
The rest is θ activity (4-7 Hz)
13
Q
Describe delta sleep brain waves.
A
Slow wave, very high amplitude, very low frequency (0.5-2.5 Hz), deepest stage of sleep
14
Q
Describe REM sleep brain waves.
A
Low amplitude, fast frequency, θ wave, sawtooth waves, where the bizarre and fantastic dreams occur
15
Q
Describe slow waves in deep sleep.
A
Coordinated silencing of neurons in multiple brain areas
16
Q
How much time is spent in REM/NREM sleep?
A
In 8 hours of sleep, 80% of time in NREM and 20% in REM
17
Q
How long does it take for the average adult to fall asleep and reach REM?
A
10-20 minutes to fall asleep, 90 minutes to reach REM
18
Q
How common is it to wake up during the night?
A
Many people wake up 10-15 times per night, only remember if we’re awake for more than 2 minutes
19
Q
What are the patterns of deep sleep, stage 2, and REM sleep in a typical 8 hour night of sleep?
A
Deep sleep only in first half of the night, REM increases throughout the night, stage 2 equal throughout
20
Q
How is the sleep cycle different in rats/mice?
A
Still have NREM and REM but go through cycles much faster
21
Q
What does respiration look like during NREM and REM?
A
NREM: deeper and regular, end expiratory carbon dioxide increases (blow off more)
REM: rate and depth variable
22
Q
What is the effect of REM and NREM on temperature regulation?
A
NREM: normal regulation
REM: paralysis results in no shivering - can’t thermoregulate - we wake up if it’s too cold
23
Q
What are the components of sleep health?
A
Sleep duration, timing, regularity, and quality
24
Q
Describe the importance of sleep duration.
- What is the necessary amount of sleep needed per night
A
Adults aged 18-60 should sleep at least 7 hours per night, correlation between less sleep and obesity, diabetes, etc due to loss of stage 2 and REM sleep
25
Describe the importance of sleep timing.
Later sleep timing = worse sleep health, greater association with disorders
26
Describe the importance of sleep regularity.
General consistencies = healthy
27
Define and describe the importance of sleep quality.
Defined as subjective perception, can tell by some measurements such as how fragmented sleep is
No standard markers but evidence for sleep efficiency (time in bed asleep/time in bed), fewer awakenings and less WASO (wakefulness after sleep onset)
28
What is social jetlag?
Sleeping in on the weekend causes brain to be on a different “time zone” during the week, causes jetlag - shown by difference in midpoint of sleep
29
Define sleep latency.
The time it takes someone to fall asleep
30
What are the objective measures of sleepiness?
Multiple sleep latency test (MSLT): attempts to fall asleep 20 minutes test, if avg is 8 minutes or less = excessive sleepiness
Maintenance of wakefulness test (MWT): attempts to stay awake in dim lights, comfy
31
What are tests for subjective measures of sleepiness?
Karolinska sleepiness scale (KSS) and Epworth sleepiness scale (ESS)
32
What is the two process model of sleep regulation?
Controls and regulates sleep - sleep-wake homeostasis and circadian rhythm
33
Describe process S.
Sleep homeostasis: we build up our drive to sleep over the day from when we wake up to when we sleep, affected by what we do while we’re awake and how long we’re awake
34
Why don’t we get progressively more sleepy over the day?
Circadian drive for wakefulness counteracts homeostatic drive for sleep by increasing over the day
35
Define slow wave activity.
Delta activity: computer assessment of the amplitude of brain waves while sleeping - they are higher if we’ve been awake longer, is a measure of our sleep need but can only be seen when we fall asleep, declines in a course of sleep as sleep drive dissipates
36
What is the effect on SWA (slow wave activity) during sleep deprivation?
Increased “sleep pressure” when sleep is insufficient or absent - results in more slow wave activity at the beginning of sleep
37
How does a nap affect SWA?
Decreases sleep pressure so drive to sleep is less and less SWA at the beginning of sleep
38
How does physical activity affect SWA?
More physical activity = more sleep need = more SWA at beginning of sleep
39
Define process C.
Circadian physiology
40
Define ɸ in circadian terminology.
Phase: time within the circadian cycle at which a particular event occurs (e.g. onset, minimum, maximum)
41
Define τ in circadian terminology.
Period: cycle length/period of an oscillator; the time it takes to get from the phase on one day to the same phase on the following day
42
Define T in circadian terminology.
Zeitgeber (time giver) period: day length (12:12 light dark cycle)
43
Define Ѱ in circadian terminology.
Phase angle: time within the circadian cycle relative to other events (biological or environmental) at which a particular event occurs (e.g. timing of DLMO relative to habitual sleep time)
44
Define amplitude in circadian terminology.
Half the distance between the peak and the trough of the rhythm or the distance between the mean/mesor (central tendency of the fitted curve) and peak
45
Define acrophase in circadian terminology.
Peak - look at fitted line to determine
46
Define nadir in circadian terminology.
Minimum or trough - look at fitted line to determine
47
Describe circadian degrees in circadian terminology.
Time is circular, hour is 15º, 0º = 360º - minimum usually
48
Describe the heliotrope experiment.
Studied heliotropes which are open during the day and close at night, he put the plant in the cupboard and it still followed the same rhythm suggesting rhythm was due to a circadian clock not the sun
49
Describe the E. coli lipopolysaccharide experiment.
Gave mice E. coli lipopolysaccharide which causes an immune response at different times during the day. The mice that were exposed during the day (when they would normally be sleeping) had a high % death but the mice exposed at night (when awake) had a low % death
50
What is the SCN?
Suprachiasmatic nucleus - located in the hypothalamus, location of internal circadian clock in mammals, self sustained clock even when out of the body
51
Describe constant routine protocol.
Gold standard to assess circadian phase, sees if a rhythm is circadian, constant environmental conditions (dim light, same temp) and constant behavioral conditions (bedrest, hourly snacks, continuous wakefulness)
52
Why is the constant routine the gold standard method to assess circadian phase?
It equally distributes factors impacting rhythms across the circadian cycle
53
What are the circadian phase markers in humans?
Melatonin (rises few hours before bed, drops after wake), cortisol (rises throughout night and drops during day), body temperature (lower during sleep)
54
How is melatonin made and where does it go?
SCN uses the sympathetic nervous system to deliver info to the pineal gland to produce melatonin which goes to MT-1 and MT-2 membrane bound receptors and MT-3 intracellular receptors
55
Describe the relationship between glucose utilization and circadian rhythm.
SCN causes more glucose utilization during the light phase even in nocturnal animals
56
What happens when the SCN is removed?
Still has circadian rhythm, shows it doesn’t require input or neural connections and that the SCN is the only thing that regulates our internal clock
57
Define forced desynchrony.
Force a much different clock so the SCN can’t control timing
58
What were the results of forced desynchrony in humans?
Average of 24.15 hour clock, some people shorter clock (morning people) and most later clock (night people) - shows internal clock is genetically driven
59
How did internal clocks affect fitness in cyanobacteria?
The species that had an internal clock closer to the light dark cycle survived and competed out the other species, even if they started with an advantage. Shows having periodicity helps survival
60
Why are humans on a 24 hour cycle when they average a 24.15 hr intrinsic circadian cycle?
Visual perception resets our circadian clock and brings us onto the same schedule
61
What is entrainment?
Daily adjustment to the circadian period - period of the oscillation (biological circadian tau) becomes equal on average to that of the synchronizer (T length)
62
What are the types of entrainment?
Daily phase delay (for morning/ <24hr people) or daily phase advance (for >24hr people)
63
What are ganglion neurons?
Output neurons of the eye that give information to the brain (from rods and cones). Novel photoreceptors that sometimes contain melanopsin
64
Define melanopsin.
Blue light photoreceptor in ganglion neurons activated by photons in the blue light spectrum. Gives info directly to the SCN and is the main contributor to affect on circadian rhythm due to light - not much effect on vision
65
How was melanopsin discovered?
Scientists used techniques to knock out rods and cones individually and mice could still shift to 24 hr cycle without them - they were blind but could still respond to light for circadian rhythm
66
What happens if melanopsin is knocked out?
Rods and cones can still communicate to the SCN through the ganglion cells
67
What are the two pathways of giving light info to the SCN?
Photic input → intrinsically photoreceptive (melanopsin containing) retinal ganglion cells (ipRGCs) → SCN
Photic input → retinal photoreceptors (rods and cones) → ipRGCs → SCN
68
What time of day is best to entrain humans to a 24 hour clock?
Morning light → phase advances
69
What happened when subjects camped and were exposed to only the light dark cycle?
Melatonin onset happened at sunset, melatonin offset happened around sunrise
70
What does this show us?
Light in the modern world shifts our biological night
71
Describe a physiological dose of exogenous melatonin.
<0.5 mg - produces endogenous levels similar to what’s seen physiologically
72
Describe a pharmacological dose of exogenous melatonin.
0.5-10 mg - produces endogenous levels greater than seen physiologically
73
How does exogenous melatonin affect the SCN?
Causes phase advances where light would cause delays and vice versa, shifts the SCN
74
What are the three neurophysiological processes that integrate to impact cognition?
Circadian rhythms, sleep homeostasis, and sleep inertia (grogginess after wake)
75
Describe the daily pattern of cognitive function.
Poor performance immediately after waking, max performance 2 hours after waking up, afternoon slump, and decrease after 1 night of sleep deprivation
76
Does performance continually stay bad after missing a night of sleep?
No - performance improves after 26-28 hours awake because of circadian rhythm
77
When do most sleepiness-caused crashes happen?
7-8 am - right after wake
78
How does performance impairment compare between sleep deprivation and alcohol impairment?
Alcohol impairment causes continual decline with higher BAC, sleep deprivation causes plateau for 16 hours, steady decline for the next 8, and increase after that due to circadian rhythm (doesn’t reach same level as before though)
Sleep deprivation induces performance deficits equal to alcohol intoxication
79
How is the homeostatic drive for sleep affected by sleep deprivation?
Continues to build but is counteracted by circadian rhythm when time to wake up
80
What is the pattern of the effect of insufficient sleep on vigilance performance?
Positive linear relationship between days without sleep and lapses of attention - no plateau indicated no adaptation to lack of sleep
81
Did 3 days recover 8h TIB return PVT performance (lapses of attention) to baseline?
No but some returned subjective sleepiness to baseline
82
What are the factors influencing sleep inertia?
Sleep stage at awakening - deep sleep sleep inertia is the worse waking up from
Circadian phase - waking up at night = more sleep inertia
Drugs - alcohol and sleeping meds make it worse, caffeine makes it better
83
How are naps affected by sleep inertia?
Reduce sleep drive - short naps are better because you’re not waking up from slow wave sleep (less sleep inertia)
84
Does adrenaline affect bad effects from sleep inertia after wake?
No - pilots still had higher rate of crashes in the morning right after waking up
85
Does circadian phase have an impact on performance based on hours awake after forced desynchrony?
Performance gets worse with more hours awake regardless of circadian phase
86
Does all life sleep and do they all show REM/non REM cycles?
We don’t know if all life sleeps but not all life shows REM/non REM cycles
87
Describe sleep in mammals.
Cyclical alternation between NREM and REM, TST varies from <3hr to >20 hrs, REM varies from 0-8hr per 24hr day
88
Do genetics determine how an animal sleeps?
There are genetic differences in how much we sleep but genetics don’t describe species differences of sleep to other species
89
Describe sleep in the bottlenose dolphin.
Unihemispheric sleep - half the brain is asleep and half is awake at the same time - allows them to continuously swim and breathe
Don’t have REM sleep because can’t surface to breathe when paralyzed
Left eye is closed when right hemisphere is is asleep and vice versa
90
Describe REM sleep in mammals.
All terrestrial mammals recorded have REM sleep, dolphins and whales have little or no REM sleep, fur seal has little or no REM sleep when it has USWS
91
How does basal metabolic rate affect non REM sleep?
Higher = less non REM sleep → need to give body food to keep up with rate
92
How does trophic position affect REM sleep?
Negative association with sleep → less REM sleep if you’re prey for less risk
93
How does sleep exposure index affect REM sleep?
Where you sleep (how exposed it is to prey) → high exposure = less REM
94
How does gestation period affect REM sleep?
Less developed at birth = more REM sleep
95
Describe hibernation.
Temperature of 5ºC for months - reduces energy needs, stores last a long time
96
Describe torpor.
Temperature lowered to ~15-20ºC for several hours - reduces energy needs but not as much as hibernation
97
What is the difference between sleep and hibernation?
Animals arouse regularly from hibernation despite high energetic costs and go to sleep - SWA is high at the initiation of the sleep episode and subsequently decreases (comparable to sleep deprivation)
98
How are torpor and sleep related?
Build up sleep drive during torpor (similar to sleep deprivation) so higher SWA coming out of torpor
99
Describe sleep in birds.
Like mammals - have very fast cycles of NREM and REM sleep, most don’t lose muscle tone during REM, waterfowl can sleep while swimming, migrators have more wakefulness and drowsiness
100
What did the sandpipers show as far as sleep?
Forgo typical sleep during mating season - birds that are more active have more mates and produce more offspring
101
What is the basic definition of sleep?
Minimal movement, typical sleep posture, reduced responsiveness to external stimulation, quick reversibility of reduced responsiveness, homeostatic compensation for the loss of sleep
102
Describe sleep in flies.
Episodes of immobility, species specific posture/resting place, increased arousal threshold, homeostatic regulatory mechanism (with sleep deprivation takes even longer to arise), responsiveness to sleep and wake promoting drugs
103
How does brain maturation at birth affect sleep?
Species with greater brain maturation at birth have state concordance (less REM sleep, more consolidated REM) earlier after birth
104
Describe the consolidation of sleep and wake.
Gradual process, greater amounts of sleep than wake in early weeks, unpredictability of waking episodes for the first 3 months, 25 hour period at 5 weeks, well consolidated waking/sleeping at 15 weeks (circadian system kicks in)
105
Why do infants have such a different sleep pattern?
Need to eat frequently, circadian rhythm not developed yet and they sleep because of process S
106
Define active sleep.
Seen in infants, precursor to REM: uneven respiration, muscle atonia but many myoclonic jerks (facial muscle activity), continuous EEG activity, rapid eye movements
107
Define quiet sleep.
Seen in infants, precursor to non REM: even respiration, inactive, discontinuous EEG (trace alternant), no eye movements
108
Describe indeterminant sleep.
Not easily categorized into either state (active/quiet)
109
What does progression of stages of sleep look like in infants?
Active → quiet
110
How does each stage change as infant matures? '
Trace alternant:
Sleep spindles:
NREM stages:
K complexes:
SWS:
Trace alternant: disappears after 6 weeks
Sleep spindles: appear after 4 weeks
NREM stages: differentiate by ~6-9 weeks
K complexes: appear about 6 months
SWS: emerges at ~3-6 months
111
What is the length of a sleep cycle at birth?
50 minutes
112
how do sleep pattern changes over the life cycle:
Newborns/infants:
Toddlers:
Children:
Adolescents:
Newborns/infants: More active in sleep; 50% REM; several periods of sleep; need naps
Toddlers: Sleep begins to resemble adult patterns
Children:Experience more deep sleep
Adolescents: Shift to later sleep-wake cycle; experience daytime sleepiness
113
What is a trace alternant?
Burst of high amplitude
114
How do sleep spindles change in infants versus adults?
Longer in infants, get shorter as you age
115
How does high amplitude SWS change with age?
Amplitude increases until 12-14 years then slightly decreases
116
What is the importance of naps?
Taking away a nap from a child → become emotionally challenged, less brain function
117
How is total sleep affected by age?
Huge variability in total sleep in infants compared to older humans, declines as you age
118
How is nighttime sleep affected by age?
Lower as an infant, increases when circadian rhythm kicks in, decreases throughout the life afterward
119
When do circadian rhythm and melatonin rhythm emerge?
Circadian system develops and consolidated sleep at night emerges around 2-3 months; melatonin rhythm emerges around 3 months
120
When should toddlers be put to bed?
After their DLMO (dim light melatonin onset) because it’s their biological night
121
What is the association between melatonin onset and sleep onset latency in toddlers?
Its harder for toddlers to fall asleep when melatonin onset occurs after putting them to bed and leads to less success putting them to bed
122
How can DLMO be shifted earlier?
Enhance light in the morning, dim light at night, don’t use tablets before bed, don’t use exogenous melatonin
123
What is SWA?
Slow wave activity - primary marker of sleep homeostasis, decreases over the night as we dissipate sleep drive
124
What is the pattern of SWA over a lifespan and how do we know?
Increases until 12 years old then decreases, know based on amplitude of SWA
125
Why does this pattern occur?
Cortical synaptic density (more synapses = more neuronal connections = greater SWA amplitude) increases as children grow up
126
How are the parts of the brain affected differently by maturation of SWA?
Adults have high amplitudes in the front of their brain, children in the back which progresses to front as they age
127
What is the tanner scale?
Scale of physical development that defines maturation based on sex characteristic (stage 1-5)
128
How is SWA different in stage 1 vs 5 on the tanner scale and why?
Higher amplitude SWA decreases with sexual maturation, dropoff of neural connections during puberty (cortical synapses are pruned)
129
What is the decay time constant?
How fast sleep drive is dissipated
130
What is the rise time constant?
Build up of sleep drive
131
How are the decay and rise time constants affected from stage 1-5 on the tanner scale?
Decay time constant is the same but rise time constant is increased as you mature so you can stay awake longer
132
How does DLMO change from stage 1-5 on the tanner scale?
Timing of DLMO starts late with more mature adolescents
133
What contributes to the circadian phase delay in adolescents?
Increased exposure to light in the evening
134
Are sleep problems common?
Not uncommon in children, only an issue if they persist without declining as you age
135
What are some examples of social/cultural impact at different ages?
Infant cosleeping
Children and quality time with parents (stay up later to spend time with them after work)
Adolescents and school start time
College students and lifestyle choices
136
Which of these factors change across the lifespan and how?
Overall sleep time:
Sleep latency:
WASO:
REM:
SWS:
Stage 2 sleep:
Stage 1 sleep:
Deep NREM sleep (stages 3/4):
Homeostatic sleep drive:
Overall sleep time: sleep more in early childhood, decreases as age
Sleep latency: constant
WASO: increases over lifespan (more/longer awakenings)
REM: constant
SWS: large decrease from childhood to adulthood (less deep sleep)
Stage 2 sleep: constant
Stage 1 sleep: constant
Deep NREM sleep (stages 3/4): reduced with age
Homeostatic sleep drive: reduced with age, underlies changes in WASO and deep sleep
137
What factor contributes to reduced homeostatic sleep drive with age?
Physical activity: more active in the day leads to better quality of sleep, older adults are generally less active
138
What is an odds ratio?
Ratio of the odds of an event in an exposed group to the odds of the same event in a nonexposed group
139
How do you interpret an odds ratio?
OR > 1 → exposure is associated with increased risk of outcome
OR < 1 → exposure is associated with decreased risk of outcome
OR = 1 → exposure does not affect odds of outcome
140
How do you interpret confidence intervals for odds ratios?
95% confidence interval determines the precision of the OR
Large 95% confidence interval indicates low level of precision
Small 95% confidence interval indicates high level of precision
141
Does a p value <0.05 or <0.0001 have more significance?
They have the same level of significance because scientists use < 0.05 to determine yes or no
142
What is the effect of sleep on age related problems and what are some examples?
Insufficient sleep and insomnia result in higher odds of developing age related disorders such as heart disease, lung disease psychological disorders (mood, anxiety, depression, etc)
143
How are insomnia and WASO affected by age?
Both are increased with increased age
144
What are the 4 factors affecting ability to sleep in the elderly?
1. Medical illness
2. Medications/polypharmacy
3. Circadian rhythm disturbances
4. Primary sleep disorders
*bidirectional process - sleep makes disorders worse and vice versa
145
How can us as future doctors help patients with medical conditions?
Many are comorbid with insomnia, paying attention to sleep issues can improve the quality of life for people with these conditions
146
Which drugs can contribute to insomnia?
CNS stimulants, chemotherapy, alcohol, etc.
147
Which drugs cause sedation/daytime fatigue and what is the effect?
Anti-hypertensives, antidepressants, etc - sedating drugs, if taken during the day can cause napping and might interfere with nighttime sleep
148
What is sleep apnea?
Cessation of breathing during sleep: two types - upper airway occluded or central (no signal to breathe)
149
How is sleep apnea affected by age and gender?
Increases with age, more prevalent in men
150
What changes in sleep occur with older adults?
Phase advance - older adults go to bed earlier (opposite of adolescents)
Reduced circadian amplitude
Earlier clock hour for circadian melatonin phase
Advanced sleep time and wake time than desired
Shorter sleep duration
151
What does excess wakefulness in older adults tell us?
They sleep as poorly during their biological night as young adults sleep during their biological day (if on shift work or if have jetlag)
152
What are the consequences of disturbed sleep?
1. Difficulty sustaining attention
2. Slowed response time
3. Difficulty with memory
4. Decreased performance
153
What can these be misinterpreted as?
Dementia
154
Describe the adaptive/time filling function of sleep.
Predator/prey relationships - animal performance and prey availability peak at specific times of the day. The suppression of motor activity during sleep prevents animals from attracting attention of predators
155
Describe the energy conservation function of sleep.
Brain/body temp reduced during sleep, NREM sleep associated with ~30% reduction in cerebral energy consumption relative to quiet waking, energy conserved in sleep can be redirected to support other functions (immune)
156
Describe the conditions of the experiment with the rats and the turning plate?
2 rats, separate chambers, if experimental rat falls asleep, plate turns and it falls into water - keep him awake. Other rat can sleep while experimental rat feeds/bathes
157
What were the results of this experiment?
Experimental rat can last 3-6 weeks before dying due to thermoregulation and increased risk of sepsis
Sleep deprived rat expended much more energy due to being awake more
158
What is the relationship between sleep deprivation and energy expenditure in humans?
Sleep deprivation causes higher energy expenditure
159
Describe brain maturation generally.
From newborn - 2 years, major growth in number and density of neurons, occurs during sleep preferentially, connections strengthened during sleep, REM is preferentially important for brain maturation
160
How does sleep cause restoration?
1. Replenish neurotransmitters
2. Facilitates protein synthesis
3. Sleep dependent hormone release
4. Replenish energy stores/glycogen
5. Reduced reactive oxygen species (ROS) and alleviates oxidative stress
161
Describe the relationship between sleep and oxidative stress.
Sleep deprivation - reduced antioxidant activity in hippocampus and brainstem
Sleep clears ROS, ROS promote sleep
162
Describe use dependent recovery.
After using (a hand) all day - the cortex that was stimulated by the movement has more SWA during sleep (more drive to sleep)
163
Describe the processes of memory consolidation.
Acquisition: introduction of new info into the brain
Consolidation: process by which memory becomes stable (strengthened)
Recall: ability to access information
164
When do each of these processes occur?
aquisition, recall and consolidation
Acquisition and recall occur during wakefulness, consolidation occurs mostly during sleep (some when awake)
165
Describe declarative memory and when it is consolidated.
Fact based, what we know
Consolidated during NREM sleep
166
Describe procedural memory and when it is consolidated.
Remembering how to do something
Consolidated during REM sleep
167
How can we see memory consolidation during sleep?
Same order of brain waves that occurred while making the memory replays during slow wave sleep but more quickly
168
Define long term potentiation.
Brain (synaptic plasticity) - 1 neuron stimulates another and each time the connection is made stronger so that you get more response for less stimulation
169
How does sleep affect long term potentiation?
Induction of LTP is impaired after continuous wakefulness and restored after sleep
170
Describe synaptic homeostasis hypothesis.
Synaptic potentiation during the day - increases need for energy and supplies, increased cellular stress, net increase in synaptic strength
Synaptic downscaling - some connections are weakened at night to get rid of unimportant synapses - restoration of energy, supplies, extracellular space, etc., net decrease in synaptic strength
171
Describe circadian functions of brain (synaptic) plasticity.
Sleep wake cycles drive synaptic protein abundance
A circadian clock drives synaptic RNA accumulation “anticipating sleep” so that the building blocks are ready to create proteins during sleep
172
How does sleep affect immune function?
Bidirectional links between sleep and immune function (promote eachother), sleep supports the initiation of adaptive immune responses (memory of the immune system)
173
Why is brain cleansing necessary?
High metabolic rate in brain leads to toxic byproducts, including proteins that lead to neurodegenerative disease, brain doesn’t have a conventional lymphatic system to clear them
174
How does sleep affect brain cleansing?
Sleep drives metabolic clearance from the adult brain - most CSF flow during sleep (and under anesthesia) due to a greater extracellular space (from decrease in synaptic strength) which clears toxins more efficiently
175
How is the process of cleansing disturbed?
Sleep deprivation and sleep fragmentation result in less clearance
176
What was seen in patients who died of insomnia?
Inflammatory lesions of the anterior hypothalamus
177
What part of the brain is important for spindles and high amplitude slow waves
Thalamus
178
Describe the ascending arousal system in the brain.
Sensory inputs that are critical for wakefulness go from midbrain and brainstem (pons and medulla) to the cortex
179
What does wakefulness depend on?
Activity of neurons within the brainstem and reticular formation
180
Where is REM sleep located in the brain?
Pons (upper brainstem)
181
Does wakefulness/sleep require input from the periphery?
no
182
What is the Raphe nucleus?
Produces serotonin which is important for the transition from sleep to wake
183
What is the role of the hypothalamus in sleep?
Primary active NREM sleep promoting region
184
Describe the role of each part of the brain in the control of wakefulness.
Locus coeruleus: norepinephrine important for arousal and attention
Raphe: in upper brainstem, promotes wakefulness, transition to sleep
vPAG: dopamine important for arousal
TMN: in hypothalamus, histamine (wake promoting neurotransmitter)
Lateral hypothalamus: orexin - stabilizes wakefulness
Basal forebrain: ACh promotes wakefulness
LDT: ACh
PPT: ACh
185
Which of these project to straight to the cortex vs going through thalamus?
LDT and PPT project to the thalamus and then to cortex, all others project straight to the cortex
