chapter 13 Flashcards
- Define and provide examples of circadian, ultradian, and circannual rhythms.
Circannual: Yearly; Migratory cycle of birds
Circadian: Daily; human sleep-wake cycle
Ultradian: Less than a day; human eating cycles
Infradian: More than a day; Human menstrual cycle
- Define and give an example of zeitgeber. Define entrain and free-run. What is the retinohypothalamic pathway? From what cells does it originate? Where does it terminate? How is the pineal involved and what does it produce?
Zeitgeber: Environmental event that entrains biological rhythms; a time setter
-Example: Light resets the biological clock.
Jet Lag: Fatigue and disorientation resulting from rapid travel through time zones and exposure to a changed light–dark cycle
–Suprachiasmatic nucleus (SCN): the master biological clock; main pacemaker of circadian rhythms located just above the optic chiasm
Retinohypothalamic Pathway: Neural route from a subset of cone receptors in the retina to the Suprachiasmatic Nucleus (SCN)
-Allows light to entrain rhythmic activity of
SCN
-Begins with specialized retinal ganglion cells
(RGCs) that contain the photosensitive
pigment melanopsin
-The retinohypothalamic tract activates core
cells.
-Core neurons are not rhythmic, but they
entrain the rhythmic shell neurons.
- Describe the hamster study providing evidence of the SCN as the location of the biological clock.
After lesions to the SCN, hamsters eat and sleep a normal amount, but rhythmic nature of these behaviors disappears.
If SCN cells from embryos are transplanted into lesioned animals, they will re-establish circadian rhythms.
- What is “REM” sleep?
Rapid eye movement (REM)- sleep associated with dreams and memory consolidation
-N-sleep dominates the early sleep periods,
and R-sleep dominates later sleep.
-Adults who sleep 8 hours spend about 2 of
those hours in R-sleep.
-The duration of R-sleep varies with age and
changes dramatically over the life span.
–R-sleep is high in infancy; increases
during growth spurts, in conjunction with
physical exertion, and during pregnancy.
- How do REM sleep brain waves compare to waking brain waves? What is the major difference between the first and second halves of the night?
N-sleep dominates the early sleep periods, and R-sleep dominates later sleep.
N-sleep:
-Large range of activities
-Decrease in body temperature, increase in
growth hormone release
Dreaming occurs in N-sleep, but dreams are not as vivid as in R-sleep except for night terrors; Brief, very frightening dreams;May affect children
-Sleeptalking
-Sleepwalking
-Night terrors
Talking or grinding teeth
Flailing, banging an arm, kicking a foot
Maintaining muscle posture during N-sleep
-Sleep may occur in a variety of postures,
including standing up, sitting, or in any of
several reclining positions.
vs
R-Sleep:
Atonia: No tone; condition of complete muscle inactivity produced as sleep regions of the brainstem inhibit motor neurons
Mechanisms that regulate body temperature stop working.
-Body temperature moves toward room
temperature.
Vivid dreams occur during R-sleep.
-Everyone dreams several times each night.
-Dreams appear to take place in real time;
dream sessions get longer throughout a
sleep session.
- How does sleep change across the lifespan, and what does this tell us about the likelyimportance of sleep for brain development?
Adults who sleep 8 hours spend about 2 of those hours in R-sleep.
The duration of R-sleep varies with age and changes dramatically over the life span.
-R-sleep is high in infancy; increases during
growth spurts, in conjunction with physical
exertion, and during pregnancy.
- Describe the effects and/or dangers of sleep deprivation. Compare long-term vs short-term deprivation effects. What are possible functions of sleep? What is brainwashing?
Recurring periods of brief sleep deprivation and irregular sleep have adverse physiological consequences, poorer health, and decreased cognitive performance.
-Performance on tasks that require attention
declines as a function of hours of sleep
deprivation.
-In humans, sleep deprivation impairs many
functions, but recovery after restored sleep is
substantial.
Sleep for Memory Storage:
Sleep solidifies and organizes memory.
-Memory storage takes time.
Memory storage is best achieved with:
-Repeated practice with intervals between the
practice.
-Memory rehearsal using frequent recall.
Two formative studies demonstrate that the events of a day are replayed during sleep.
-Sleep and explicit memory
-Sleep and implicit memory
- What parts of the brain play important roles in sleep?
RAS: Reticular Activating System; the sleep/wake controller
-Is complex and may feature as many as 100 different regions or nuclei.
-Incoming sensory pathways are sent to RAS.
-The RAS is the source of waking, and sensory
stimulation produces waking because it
activates RAS neurons
- Why might we dream? When do we dream?
- Memory Consolidation: Dreams may help consolidate and process memories from the waking day, aiding in long-term memory storage
- Emotional Processing: Dreaming might help us process emotions, allowing us to cope with stress, trauma, and other experiences.
- Creativity and Problem-Solving: Dreams can foster creativity and problem-solving by allowing us to explore different possibilities and think outside the box
- Self-Awareness: Dreams may help us develop self-awareness by reflecting on our thoughts, feelings, and motivations
As for when we dream, it primarily occurs during the Rapid Eye Movement (REM) stage of sleep, which typically begins about 60 to 90 minutes after falling asleep. However, dreams can also occur during other stages of sleep, though they are usually less vivid and memorable.
- How does the pattern of brain activation during REM sleep help explain some of the content of dreams?
- Limbic System Activation: The limbic system, which includes structures like the amygdala and hippocampus, is highly active during REM sleep. This area of the brain is associated with emotions, which explains why dreams often have strong emotional content.
- Frontal Cortex Deactivation: The prefrontal cortex, responsible for logical thinking, decision-making, and self-control, is less active during REM sleep. This reduced activity can lead to the bizarre and illogical nature of dreams, where time and space may seem distorted, and events can be surreal.
- Increased Visual Cortex Activity: The visual cortex, which processes visual information, is also more active during REM sleep. This heightened activity contributes to the vivid and often visually rich nature of dreams.
- Memory Processing: REM sleep is crucial for memory consolidation. The hippocampus replays recent experiences, which can be integrated into dreams, sometimes in a fragmented or symbolic manner.
- You should be able to recognize the sleep disorders we discussed (ie, I give symptoms, you give diagnosis).
The International Classification of Sleep Disorders lists six categories of sleep disorders:
1. Insomnia: Symptom of several disorders characterized by an inability to fall asleep, stay asleep or experience satisfactory sleep
-Drug dependence insomnia: Syndrome in
which patients unsuccessfully attempt to
sleep by increasing their drug dosage
-Fatal familial insomnia: An almost complete
inability to sleep
- Hypersomnia: Disorder of falling asleep at inappropriate times, or a difficulty staying awake
-Sleeping beauty syndrome (Kleine–Levin
syndrome): Rare condition in which the
affected individual has recurring bouts of
excessive sleeping
- Breathing disorders:
-Sleep apnea: Inability to breathe during
sleep, causing a sleeper to wake up to
breathe
-Central nervous system apnea: Produced by
a CNS problem, such as weak neural
command to the respiratory muscles
-Obstructive sleep apnea: Caused by collapse
or blockage of the upper airway
- Parasomnias: Are unusual and unwanted behaviors that disrupt sleep; can occur at any point in the sleep cycle
-N-parasomnias; R-parasomnias
-Sleep terrors (night terrors): N-parasomnias
that may involve intense screaming, crying,
thrashing, or fear that occurs again and again
throughout successive nights’ sleep
-Sleepwalking (somnambulism): N-
parasomnia that involves getting up and
walking about
-Sleep-related eating disorders: Eating instead of going to bed; N-parasomnia
–Triad of nocturnal hyperphagia
(excessive hunger and eating), insomnia,
and morning anorexia often displayed
-Nightmare disorder: Vivid dreams marked by
intense feelings of dread or terror that
awaken the individual; nightmare distress;
occurs during deep sleep/R-sleep
-Sleep paralysis: Atonia and dreaming occur
when a person is awake, usually just falling
asleep or waking up; atonia of R-sleep.
-Sleep-related hallucinations: Hallucination;
atonia of R-sleep either upon waking or going
to sleep; includes state of sleep paralysis or
cataplexy
-R-sleep behavioral disorder (R-sleep without
atonia): Behavior acted out dreams; often
associated with early symptoms of Parkinson
disease
- Sleep-related movement disorders: People can display a variety of sleep-related movement disorders.
-Bruxism: Teeth clenching or grinding
-Periodic leg movement: Arm or leg flailing,
-Hypnic jerks: Whole body or body part
movements, such as face
-Restless leg syndrome (RLS)
- Circadian-rhythm sleep disorders
