Sleep part 2
Terms in this set (30)
Explain why the neurons of the locus coeruleus are affected by drugs like amphetamine.
Amphetimine produces arousal and sleeplessness, and these effects appear to be mediated primarily by the noradrenergic system of the LC, located in the dorsal pons.
Descibe the changes in the firing rate of noradrenergic neurons in the locus coeruleus.
The firing of these neurons was high during wakefulness, low during slow-wave sleep, and almost zero during REM sleep.
What do these differences in firing rate suggest about the control of REM sleep?
People become paralyzed when in REM sleep so these active noradrenergic neurons are not working during this time.
Describe the task Aston-Jones et al. taught monkeys. How did their performance correspond to the rat of firing of noradrenergic LC neurons? What do the differences in firing rate of these neurons suggest about their role?
Monkeys who were performing a task that required them to watch for a particular stimulus on a video display had their electrical activity of noradrenergic LC neurons monitored. The monkeys performed best when the rate of firing of the LC neurons was high. After the monkeys worked for a long time at the task, the neurons' rate of firing decreased, and so did the monkey' performance. These results support the conclusion that the activation of LC neurons (and their release of norepinephrine) increases vigilance.
Where do the brain's serotonergic neurons project?
Almost all of the brain's serotonergic neruons are found in the RAPHE NUCLEI. These axons project to the THALAMUS, HYPOTHALAMUS, BASAL GANGLIA, HIPPOCAMPUS, and NEOCORTEX
How is cortical arousal affected by stimulation of the raphe nuclei, administration of PCPA?
Stimulation of the raphe nuclei causes locomotion and cortical arousal, whereas PCPA (a drug that prevents the synthesis of serotonin) reduces cortical arousal
How may serotonergic neurons be involved in an animal's ongoing activities?
Serotonergic neurons are involved in facilitating ongoing activities (such as pacing, chewing) and suppressing the processing of sensory information, preventing reactions that might disrupt the ongoing activities.
Describe the changes in the firing rate of serotonergic neurons during waking and slow-wave and REM sleep.
The serotonergic neurons (like the noradrenergic neurons) were most active during waking/ the firing rate declined during slow-wave sleep and became virtually zero during REM sleep, and the neurons became temporarily active again after the ending of REM sleep.
Where are histaminergic neurons located? Where do they project and how do they influence these regions?
They are located in the TMC, and axons of these neurons project to the CEREBRAL CORTEX, THALAMUS, BASAL GANGLIA, BASAL FOREBRAIN, and other regions of the hypothalamus.
Summarize the effects on waking and sleep of injections of drugs that prevent the synthesis of histamine or block histamine H1 receptors.
These decrease waking and increase sleep
Summarize the effects on waking and sleep of infusions of histamine into the basal forebrain region.
causes an increase in waking and decrease in non-REM sleep
When is the activity of histaminergic neurons high? Low?
The activity of histaminergic neurons is low during slow-wave sleep and REM sleep/ high during wakefulness
Explain why the control of wakefulness is not controlled by histamine alone
Mice with a targeted mutation that blocks the synthesis of histamine showed normal amounts of spontaneous wakefulness, but showed less arousal in response to new environmental stimuli
What is the role of the body's five systems of arousal?
The brain's arousal systems promote wakefulness at different times or in different situations and no one of these systems plays a critical role under all circumstances.
Where are neurons that secrete hypocretin (orexin) located, and where do they terminate?
The cell bodies of neurons that secrete orexin are located in the lateral hypothalamus, and the axons of these neurons project to almost every part of the brain.
How does hypocretin affect these regions?
It has an excitatory effect in all of these regions
Describe insomnia, including its incidence, problems of definition, and most important cause.
25% of the population are affected occasionally, 9% regularly. Primary insomnia is when people have difficulty falling asleep or after they have been woken up. Secondary insomnia is the inability to sleep due to pain, substance abuse, or a psychological disorder. Most people suffer from insomnia because their daily lives require them to work more and sleep less.
Explain how the use of sleeping medication often leads to drug tolerance and a withdrawal effect/ drug dependency insomnia.
Chronic use of sleep-promoting drugs can lead to tolerance and rebound insomnia (a return and increase in insomnia) when their use is ended.
Briefly explain why self-reports of insomnia must be regarded skeptically
People often underestimate the amount that they sleep.
Describe sleep apnea. Carefully explain the change in blood levels of carbon dioxide and its effects.
Sleep apnea occurs when a person falls asleep and then ceases to breathe. During a period of sleep apnea the level of carbon dioxide in the blood stimulates chemoreceptors and the person wakes up, gasping for air. It disrupts sleep and people feel groggy and sleep all the time.
What is a frequent cause of sleep apnea and how is it corrected?
It is often caused by an obstruction of the airway and be corrected surgically.
Describe the four symptoms of narcolepsy.
SLEEP ATTACKS: overwhelming urge to sleep that can happen at any time but occurs most often under monotonous boring conditions
CATAPLEXY: person will sustain varying amount of muscle weakness, sometimes slumping to the floor although completely conscious.
SLEEP PARALYSIS: the inability to move just before the onset of sleep or on waking in the morning.
HYPNAGOGIC HALLUCINATIONS: vivid dreams that accompany a person just before sleep, with sleep paralysis
Describe the sleep patterns of people with narcolepsy.
Go directly into REM sleep. Periods of irresistible sleep but at inappropriate times
What is the cause of human narcolepsy?
It is a hereditary disorder but it can be strongly influenced by the environment as well.
Summarize research on abnormalities in the hypocretin system that produce narcolepsy in mice and rats
A targeted mutation in mice against the orexin gene found that the animals shoed symptoms of narcolepsy. Also, a toxin that attcked only orexinergic neruons administered in rats showed that the desctruction of the orexin system produced symtpoms of narcolepsy as well.
Briefly summarize the results of analyses of the cerebrospinal fluid of nine patients with narcolepsy and the presumed cause of their condition.
It was found that a complete absence of orexin in seven of the nine patients in their cerebrospinal fluid. They hypothesized that the cause of narcolepsy in these seven patients was a hereditary disorder that caused the immune system to attack and destroy orexin-secreting neurons. Most patients with narcolepsy are born with orexinergic neurons, but during adolescence the immune system attacks these neurons, and the symptoms of narcolepsy begin.
What kinds of drugs are used to treat the symptoms of narcolepsy?
Stimulants, antidepressants, or modafinil
What happens when people suffering from REM-sleep behavior disorder dream>?
They act out his or her dreams
What are two causes of this condition? How is it treated?
Caused by a neurodegenerative disease that damages brain mechanisms that produce paralysis during REM sleep. It can be treated with benxodizepine
Describe four maladaptive behaviors that may occur during slow-wave sleep, noting any association with sleep stages, who is most susceptible, and what the best treatments are.
During slow-wave sleep some people experience betwetting, sleepwalking, night terrors, and sleep-related eating disorder. Treatments include training for bedwetting, dopamine agonists, or topiramate for sleep eating. Many children usually outgrow night terrors.
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