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