Neurophys 3 Final Flashcards
(132 cards)
Arousal systems in the brain appear to be determined by the interaction between what structures?
brainstem, hypothalamus, thalamus, and basal forebrain
Dampening of arousal systems w/concomitant (at the same time) active inhibition by thalamo-cortical systems produces _?
sleep
Name 3 areas that maintain wakefulness.
oral pontine reticular formation (glutamate), midbrain central tegmentum, posterior hypothalamus (histamine)
Name 3 sleep-promoting areas.
midline brainstem (raphe nuclei-serotonin), dorsolateral medullary reticular formation, anterior hypothalamic preoptic region (parasymp-conservation)
What is considered the sleep modulating center of the brain? what type of projections does it have? where does it project to?
Magnocellular nucleus basalis of Meynert (located in the forebrain); it has an intermingling of both sleep & waking active sites, & uses acetylcholine projections; it projects to neocortex & midbrain reticular formation
The caudal mesencephalic (cholinergic) and cells of the oral pontine reticular formation (glutaminergic) produce wakefulness & travel through ascending projections to the _ (using a dorsal pathway). These neurons also communicate w/the hypothalamus & basal forebrain using a _ pathway?
thalamus; ventral
What is a behavioral state that differs from wakefulness by a readily reversible loss of reactivity to events in one’s environment? What stages is it divided into?
Sleep; 1. electroencephalography (EEG) most commonly 2. electro-occulogram (EOG) 3. electromyogram (EMG)
Non-REM sleep aka? Which stage has high amplitude delta waves (20-50%) Which stage has theta, delta (low amplitude) horizontal eye drift? Which stage has high amplitude delta waves (>50%)? Which stage includes theta & delta waves, sleep spindles, & K complexes? Which 2 stages are light sleep?
aka slow wave sleep; Stage III; Stage I; Stage IV; Stage II; Stages I & II are considered light sleep while III & IV are deep sleep
What does REM stand for? The EEG resembles an awake state or NREM stage _? During REM, what is the result of the EMG activity?
rapid eye movement (REM); stage I; dramatic decrease in EMG activity
In REM, sleep is usually episodic, occurring roughly every _ minutes, and occurs for a _ time period than the previous REM cycle? During REM, how is one woken up from the deepest sleep? How is one woken up spontaneously from lighter sleep?
90 mins; longer time period than the previous REM cycle; external arousability for deepest sleep; internal arousability from lightest sleep
An electrical stimulation of this area of the brain produces slow wave brain sleep, and lesions here produce cortical desynchronization (waking pattern of EEG)?
nucleus tractus solitarius
Lesions in which area of the brain produce insomnia? Blocking which NT also produces insomnia?
serotonin-rich raphe nucleus; blocking production of serotonin can also produce insomnia, which can be done by parachlorophenylalanine (PCPA), a tryptophan hydroxylase inhibitor (tryptophan, found in Thanksgiving turkeys, has an abundance of serotonin & promotes sleep)
What is serotonin a precursor for? Sleepwalking aka? what type of stage is sleepwalking occuring during?
melatonin; somnambulism; occurs during slow wave sleep
Melatonin is synthesized & released by which brain area? Is it sympathetic/parasympathetic? What does melatonin enhance? Name a symptom that is treated w/melatonin.
pineal gland; sympathetic; melatonin enhances sleep (prolonged bright light stimulation suppresses melatonin & sleep); jet lag has been treated w/melatonin
Which area of brain appears to inhibit waking areas in the rostral midbrain & mesopontine reticular core?
preoptic nucleus of anterior hypothalamus
What is highly concentrated in the preoptic nucleus and induces both slow wave sleep and REM sleep? The anterior hypothalamus may also produce sleep by inhibiting the waking area in the __ __?
prostaglandin D2; posterior hypothalamus (histamine secreting)
What are rhythmic cortical waveforms generated by oscillatory activity in the nucleus reticularis of the thalamus? These, along w/delta waves, are physiologic events involving GABAergic neurons via inhibition promoting brain deafferentation (prevents senses from getting to cortex @ the level of the thalamus). what stimulate GABA receptors & facilitate sleep?
sleep spindles; sedatives (barbituates) & hypnotics (benzodiazepines)
REM sleep is read off of this diagnostic tool that becomes highly desynchronized during REM? REM sleep is associated w/these types of spikes, which themselves are associated w/many phasic events such as rapid eye movements, changes in respiration, heart rate, muscle twitches, and dreaming.
EEG; pontine geniculate occipital (PGO) spikes
PGO spikes originate from __ cells in medial pontine reticular formation & adjacent reticular tegmental nucleus? In animals, REM sleep has been eliminated by placing lesions ventral to which structure? REM-OFF cells are represented by noradrenergic cells of locus ceruleus which become _ during REM?
REM-ON; locus cereleus; silent
Many _ are REM suppressors, which increase activity of norepinephrine &/or serotonin. During REM, there is a progressive _ in muscle tone associated w/hyperpolarization of motor neurons? What is 30% greater in REM sleep?
antidepressants; decrease in muscle tone; Rheobase is 30% greater in REM (rheobase is a measure of membrane excitability, the threshold at which the stimulus causes a response); in essence, this rheobase being 30% higher during REM means it’s harder to excite those neurons when one is in REM sleep
What is the minimum time required for an electric current 2x the strength of the rheobase to stimulate a muscle or a neuron?
chronaxie
Normally, REM sleep is associated w/a progressive decrease in muscle tone associated w/hyperpolarization of motor neurons. However, in this disorder, there is persistent muscular tone during REM sleep, and it is characterized by bursts of excessive limb & body movements (although cause is unknown in humans).
REM behavior disorder
The use of _ in the 50’s & 60’s as sleeping pills proved unsatisfactory, as they led to addiction, dependence & disruption of normal sleep stages. Chronic users frequently became addicted & refractory to the drug, giving poorer sleeping habits.
barbituates
During sleep, what happens to brain & body temp? metabolism? what serves as an endogenous clock influencing both sleep & body temp in a closely-coupled fashion? brain metabolism decreases _% in slow wave sleep? what happens to cerebral blood flow during SWS (slow wave sleep)? what appears to be a somnogenic (sleep-producing) NT, which caffeine can block?
reduction of body & brain temp @ onset of sleep associated w/vasodilation; decrease in metabolism; suprachiasmatic nucleus; brain metabolism decreases 20-35% in SWS; cerebral blood flow decreases in SWS; adenosine is a somnogenic NT