Section 6 Flashcards
Sleep
The three standard methods for monitoring and recording brain and physiological activity
Electroencephalography (EEG)
Electrooculography (EOG)
Electromyography (EMG)
Which waves are present during wakefulness
non-attentive: alpha
attentive: beta
EEG Stages of Sleep
Initial Stage 1 - NREM theta waves
Stage 2: higher voltage and slower than stage 1; k-complexes and sleep spindles
Stage 3: delta waves; no spindles
Stage 4: predominantly delta waves
Emergent Stages of Sleep
Stage 1: REM Sleep
Stages 3&4: Slow-wave sleep
What stage of sleep is indicated by long slow waves on an EEG? What is the name of the slow wave?
Stages 3&4 - delta waves
[True/False] Dreaming always occurs during REM
False. Dreaming occurs more often during REM but not always
What do each of the standard measurement methods show during REM sleep
EEG - similar to wakefulness; EOG - rapid eye movements; EMG - flat (no neck movements)
What measure(s) should an investigator use to determined whether a sleeper is in REM sleep? Which part of the the night is REM most common?
EEG; REM is most common before waking up
[True/False] All birds and mammals sleep
True
The variety in sleep time among species demonstrates
sleep serves some important physiological function
sleep is not an exclusive “higher-order” human function
sleep is not necessarily needed in large quantities for all animals
Recuperation Theory of Sleep
Sleep is for repair and restoration. Being awake disrupts homeostasis and sleep is required to restore it.
Circadian Theory of Sleep
Sleep is for preservation and protection. Sleep is an adaptive response to conserve energy to protect animals from the dangers of the night and is the result of an internal timing mechanism.
Freudian Theory of Dreams
Dreams represent subconscious wishes and repressed thoughts - not much modern evidence
Activation-Synthesis Theory of Dreams (Hobson)
The cortex is activated by random signals from the brain stem (e.g. pons) and it tries to synthesize stories while asleep.
[True/False] Dreaming may help with learning
True. Demonstrated by Stickgold et al showed that dreaming about a task you’ve seen may help you complete it
Lesions to which brain areas produce a cessation of dreaming
Temporoparietal junction (TPJ)
Medial prefrontal cortex
Which brain regions are involved in the visual imagery implicated in dreams
Medial occipital lobe
Why do we consider REM sleep to be paradoxical?
During REM, the EEG patterns are similar to wakefulness
REM sleep is in some ways the deepest sleep, but in other ways the lightest
REM is characterized by rapid eye movements, increased heart rate, irregular breathing, and genital erection although core muscles are more relaxed than in other stages
Our most familiar circadian rhythm is the
sleep-wake cycle
Evidence for an endogenous biological clock
physiological and behavioral activity rhythms continue even when animals are maintained in a constant environment
Free-running rhythms (definition)
animals demonstrate regular biological cycles in a constant environment
for humans usually slightly more than 24hrs
Do animals raised in unchanging lab environments show circadian rhythms?
Yes. This is because it is intrinsic and endogenous. The sleep-wake cycle is NOT a learned behavior.
What stimulus is the most effective zeitgeber for humans? What evidence indicates that humans have an internal biological clock?
sunlight; free-running rhythms
What brain region is associated with our internal biological clock?
Suprachiasmatic nuclei (SCN) of the hypothalamus contains rhythm-generating neurons
lesions to this brain region abolish most circadian rhythms
Isolated neurons display circadian rhythms of activity
Mechanisms of entrainment
retinohypothalamic tract - direct path from the retina to the SCN; involved in allowing zeitgebers (Sunlight) to entrain the circadian cycles
Genetics of circadian rhythms (Case study)
one study was done on fruit flies where the isolated the cells to find out the molecular mechanisms of intrinsic rhythms. They found the per and tim genes. A study done later in mice found that the clock gene activates the per gene.
What are the implications from findings of circadian genes across species?
this indicates that these genes probably evolved early in evolutionary history
gene expression is triggered by light-dark cycle
Which brain area is most important for producing the circadian rhythm? How does light reset or adjust the biological clock?
SCN; light signal transmitted via the retinohypothalamic pathway
Sensory theory of sleep (Breme)
hypothesized that sleep is caused by a reduction of sensory input to the forebrain, meaning that sleep is passive. Proved wrong later
Active theory of sleep
sleep is not a state of neural quiescence and sleep-promoting circuits exist
The Reticular-Activating System
recieves sensory input and arouses the cortex,; the stimulation awakens a sleeping individual and increases altertness
[True/False] Sleep talking and sleepwalking are found to occur during dreams in the REM sleep stage
False
[True/False] Sleep relies on reducing brain activity
False
[True/False] Different brain regions are associated with REM and NREM
True
[True/False] Some part of the hypothalamus promotes wakefulness
True
[True/False] Sleep promoting brain areas were found
True
How do we differentiate between stage 3 and stage 4 sleep EEG?
the amount of large and slow EEG waves present
____ waves occur during dreaming and seem to support the _____ theory of dreaming
PGO; Activation-Synthesis
Some complications associated with treating insomnia with benzodiazepines are
cessation of use causes insomnia
chronic use can lead to dependence
tolerance develops
Neural circuits during REM
PGO waves during REM are thought to be one way in which pseudo-sensory info from the brain stem is transmitted to the cerebral cortex
The two interconnected sets of neurons in the Pons
Projection to the thalamus (ascending) - increases brain activity occurring during REM
Projection to the medulla (descending) - regulates/relaxes core muscle tone during REM
How does melatonin affect sleep?
production is regulated by the SCN to increase sleepiness
Why does melatonin have little effect if taken before bedtime?
because your body already produces melatonin at night
What would happen to a sleeper if the person’s reticular formation is being stimulated?
they would be awakened
What might happen to an animal if the pons to the medulla connection is severed?
acting out the dream
What might happen to an animal if the pons to the thalamus connection is severed?
disruptions in REM
Insomnia
complaints of little to no sleep
may be iatrogenic as a result of drug tolerance or due to sleep apnea
Hypersomnia
complaints of too much sleep and still feeling tired
Narcolepsy
overwhelming sleepiness results into sleep attacks where the person falls directly into REM sleep - cataplexy (relaxed muscle tone associated with REM)
Effects of total sleep deprivation?
little marked physiological disturbance (normal strength and motor performance) but some effects on cognitive performance related to executive function
The most reliable effect of sleep deprivation in humans is
sleepiness
Effects of REM deprivation
REM occurs more frequently
REM rebound when sleep deprivation is over
Effects of long-term sleep reduction
individuals deprived of sleep become more efficient sleepers
cognitive performance deficits accumulate over time (attention and working memory)
What is the importance of REM?
no definitive answer - drugs that block REM are not severely debilitating
How can we sleep more efficiently?
reduce amount of time in bed not sleeping
