Test 3 Flashcards
What is REM sleep?
- Associated with dreaming
- EEG activity looks as though you are awake
- Apart from physical twitching and eye darting, muscles are totally inactive
- Cerebral blood flow and oxygen consumption increase
• At the end of a REM cycle, people may wake up and reposition and fall back to sleep
What is slow-wave, deep non-REM sleep?
Sleep stages 3 and 4
- Associated with large amplitude low frequency oscillations of brain activity as measured with EEG
- This pattern of neural activity reflects bursts of action potentials that are synchronized across large collections of neurons
- Oscillatory activity is the most pronounced
What is beta activity?
- Typical of an aroused state
- Reflects dyssynchronous neural activity (high frequency, low amplitude oscillations)
What is alpha activity?
- Typical of an awake person in a state of relaxation
- Desynchronized neural activity
What is theta activity?
Appears intermittently when people are drowsy, and is prominent during early stages of slow-wave sleep
What is delta activity?
- Occurs during deepest stages of slow-wave sleep
- Reflects synchronized low frequency, large amplitude brain activity
- After stage 4, you go back into REM
What is the glymphatic system?
Waste clearance pathway of the brain; it removes excess proteins and other metabolic waste from the interstitial space in the brain (use of CSF as a filter)
- The clearance of proteins and waste products from the brain is almost nonexistent during wakefulness but really high during sleep
- In contrast, the waste clearance system in the rest of the body, the lymphatic system, is always active
What are circadian rhythms?
• The daily change in behaviour and physiological processes that follows a cycle of approximately 24 hours is known as a circadian rhythm
• They are controlled by internal biological clocks
- Regular variations in light levels keeps the clock adjusted to 24 hours
What is the suprachiasmic nucleus (SCN)?
- Located in hypothalamus, it regulates sleep cycles – it receives a direct input from the retina
- SCN lesions alter the length and timing of sleep-wake cycles, but they do not change the total amount of time that animals spend asleep
- Every cell within the SCN has its own clock
What is advanced sleep phase syndrome?
A mutation of a gene called per2 (period 2) causes a 4-hour advance in the biological clock – a string desire to fall asleep at 7pm and wake up at 4am
- Sets the clock wrong, better for them to just get used to it because their clock will not change
What is delayed sleep syndrome?
a mutation of a gene called per3 causes a 4-hour delay in rhythms of sleep and temperature cycles – a strong desire to fall asleep at 2am and wake up at 11am
What is caffeine?
an adenosine receptor antagonist
What does norepinephrine activity correlate with?
focus and attention
What does serotonin (5-HT) neuron activity correlate with?
Positively correlates with cortical arousal, and drugs that increase serotonin signalling tend to suppress aspects of REM sleep (without affecting memory)
What are neuropeptides?
they are released in many areas of the brain but are only made in small groups of neurons in the hypothalamus
What are histamine receptor blockers (antihistamines)?
Often cause drowsiness, since they could cross the blood-brain barrier
• Histamine release can cause allergies
What do neurons in the ventral lateral preoptic area (vlPOA) of the hypothalamus do?
They promote sleep
- Electrical stimulation causes drowsiness and sometimes immediate sleep
- Lesions suppress sleep and cause insomnia
- They inhibit wake-promoting neurons such as histamine, serotonin, and norepinephrine neurons
What is the function of the ventral lateral preoptic area (vlPOA)?
It receives inhibitory inputs from the same regions it inhibits ( inhibited by histamine, serotonin, and norepinephrine)
- This kind of reciprocal inhibition characterizes a flip-flop circuit; both regions cannot be active at the same time and the switch from one state to another is fast
- Either the sleep neurons are active and inhibit the wakefulness neurons, or the wakefulness neurons are active and inhibit the sleep neurons.
What is orexin (hypocretin)?
A peptide produced by the neurons in the hypothalamus that promotes wakefulness
- Absence or degeneration = narcolepsy
What is narcolepsy?
• Sleep disorder characterized by periods of excessive daytime sleepiness and irresistible urges to sleep as well as other symptoms
- It’s a hereditary autoimmune disorder
- For most with narcoleptics, this disease is caused by the death (degeneration) of orexin neurons in the hypothalamus
What is cataplexy?
complete paralysis that occurs during waking, typically precipitated by strong emotional reactions or sudden physical effort (ex: laughter, anger, excitability)
What is sleep paralysis?
REM-associated paralysis occurring just before a person falls asleep
- Often accompanied by vivid dream-like hallucinations
- Due to the lack of orexin neurons and the lack of promoting the arousal system, sometimes the REM circuits become activated while the circuit is awake, triggered by emotional reactions in the amygdala
What is insomnia?
• Difficulty falling asleep after going to bed or after awakening during the night
What is fatal familial insomnia and sporadic fatal insomnia?
• A very rare disease that involve progressively worsening insomnia, which leads to hallucinations, delirium, and confusional states
- Typically inherited but can also develop spontaneously
- Has no known cure and he average survival span after the onset of symptoms is 18 months
• Going under anesthesia gives the benefits of sleep, so this is what some people try
- However, it is risky, as too much anesthesia can be fatal
What are disorders associated with non-REM sleep (non-REM parasomnias)?
• The brain seems to get caught in between a sleeping and waking state; many people are unaware that they exhibit this behaviour
- Sleepwalking, sleep-talking, etc
- Some of these tend to be more prevalent in children
- Episodes can last seconds to minutes or longer
- These states can be caused by certain medications or medical conditions
What are sleep terrors?
Characterized by overwhelming feelings of terror upon waking
- May include panic and screaming and bodily harm caused by rash actions
- People sometimes have no recollection of these events
- Prevalent in people diagnosed with post-traumatic stress disorder
What is REM sleep behaviour disorder?
• Neurological disorder in which the person does not become paralyzed during REM sleep and thus acts out dreams
• Happens in the SECOND half of the night
- It is often associated with better-known neurodegenerative disorders such as Parkinson’s disease
- Absence of GABA signalling to regulate motor commands
What is sexual dimorphism?
• The condition where the two sexes of the same species exhibit different characteristics beyond the differences in sexual organs
- These differences may be subtle or exaggerated and can include differences in size, weight, color, behaviour, and cognition
- They include secondary sex characteristics (features that occur during puberty)
What is sexual dimorphic behaviour?
behaviours that have different forms or occur with different probabilities or under different circumstances across males and females
- In mammalian species, the most striking category of sexual dimorphic behaviours are their reproductive behaviours
- The brain gives rise to sexual dimorphic behaviours because it is a sexually dimorphic organ
What are the sex chromosomes?
X and Y
- They typically determine an organism’s sex
What are gonads?
Ovaries or testes
- they make reproductive cells called gametes, which are either ova (egg cells) or sperm
- Split to make gametes
What are undifferentiated gonads?
Embryonic precursor of ovaries/testes
What is the Mullerian system?
Embryonic precursors of female internal sex organs
What is the Wolffian system?
Embryonic precursors of male internal sex organs