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30 Cards in this Set

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What kinds of waves are seen on EEG when the subject is asked to sit quietly with their eyes closed?
Big, slow waves: they have low frequency and high ampplitude and are said to be in the alpha range (8-13Hz)
What kinds of waves are seen on EEG when the subject is awake and alert?
Beta waves, which are low amplitude and high frequency (50-60Hz)
What contributes to the large amplitude seen in alpha waves?
At this low frequency, the PSPs in the brain are synchronous and their magnitudes summate.
What contributes to the small amplitude of beta waves?
At this high frequency, the PSPs are not synchronous and thus there is no summation of their magnitudes.
What does the EEG represent?
The summed EPSPs and IPSPs produced by pyramidal neurons in the cerebral cortex.
What structure in the brain is required to maintain consciousness?
The reticular formation in the midbrain and medulla, in particular the ascending reticular activating system (ARAS).
How might increased intracranial pressure result in unconsciousness?
The cerebellar tonsils can herniate through the foramen magnum and compress the portions of the reticular formation.
What are the three major functions of the reticular formation?
1.Regulation of sleep
2.Regulation of respiration and cardiovascular function
3.Maintaining wakefulness
Where is the reticular formation located in cross sections of the medulla and pons?
*medulla: dorsal to the inferior olivary nucleus
*pons: ventral to the abducens nucleus
How many stages are seen in NREM sleep? What kind of waves appear on EEG during this kind of sleep?
*3-4 stages
*theta waves progressing to delta waves which are very low frequency (1-2Hz) and large amplitude
T/F:
Because they are a part of dreaming, sleep walking, night terrors, and enuresis occur during REM sleep.
False: these things are not a part of dreaming and in fact occur during NREM sleep.
What kind of activity during the day will lead to a high proportion of NREM sleep? What will produce a high proportion of REM sleep?
*hard physical activity leads to NREM sleep
*REM is increased after a day with a lot of new experiences
What structural components of the brain are associated with NREM sleep? How will lesions to these structures affect sleep?
Serotonin-containing neurons in the raphe nuclei of the pons and medulla. Lesions here lead to alternating cycles of REM sleep and wakefulness.
What is seen on the EEG during REM sleep?
*high frequency, low amplitude beta waves as seen in conscious subjects
Why is REM sleep sometimes called "paradoxical sleep"?
Because EEG shows brain waves similar to those produced by the conscious brain, but the subject is very difficult to rouse.
How is muscle tone affected in REM and NREM sleep?
*in REM sleep, there is descending inhibition and paralysis
*in NREM sleep there is maintenance of postural tone
How does the proportion of REM sleep per night change over the lifetime of an individual? What does this imply?
REM sleep dominates the sleep of infants and small children, and then declines. This implies that REM sleep may be necessary for normal development
How are the noradrenergic neurons of the locus coeruleus associated with REM sleep? What effect does lesioning of this structure have on REM sleep?
These neurons are thought to mediate the muscular paralysis seen during REM sleep. Lesions may result in the subject acting out their dreams.
What aspect of learning seems to be associated with REM sleep? What is the evidence for this link?
Memory consolidation - the same temporal pattern of neuron firing is seen during REM sleep as during the learning session.
How long is each cycle of sleep?
~90 minutes
As sleep cycles progress through the night, how do the proportions of each kind of sleep change?
The periods of delta (NREM) sleep decrease and the periods of REM sleep increase.
What effect does sleep deprivation have on the proportional needs for REM and NREM sleep?
It increases the need for REM sleep, and upon return to sleep this stage will be reached very quickly at the expense of NREM sleep.
What process can confound studies about sleep deprivation?
Microsleeps.
How does profound sleep deprivation affect metabolism?
It produces a significant derangement with dramatic weight loss despite increased intake. Death has been shown to occur within one month due to weight loss.
What effects does selective deprivation of REM sleep have?
*rebound REM sleep on subsequent nights
*deficits in non-declarative learning
What is cataplexy? What conditions can trigger an attack?
*Breakthrough of REM descending muscular inhibition during waking hours
*experience of strong emotion
Other than cataplexy, what symptoms are associated with narcolepsy? What is the prevalance of this condition?
*breakthrough of REM sleep during waking hours
*hallucinations as dream states impinge consciousness
*1:1000
What is orexin? What functions does it attend to? Where is its receptor expressed?
*a peptide that is involved in wakefulness, sexual function, and feeding behaviors
*the receptor is expressed in a small portion of the lateral hypothalamus
What effects are seen with a deficiency of orexin?
*narcolepsy
*anorexia
*erectile dysfunction
There is a small genetic commponent to narcolepsy in humans - what other etiology has been proposed?
That narcolepsy is an autoimmune condition, as evidenced by the fact that it can diagnosed with HLA markers.