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PSYC473 Exam 2
| Question | Answer |
|---|---|
| Sleep | 24 hour light/dark cycle which entrains the circadian clock, varies in between species Most obvious: noturnal and diurnal |
| Rest/Activity | Animals constant is LL or DD--LL has many effects on the rest/activity rhythm because the clock is always stimulated by light Animals in long period of time in LL and then put in LD the change in environment changes activity |
| Definition of Sleep | Behavioral state different from wakefullness reversible physiological state in mammals 1. characteristic changes in posture 2. raised sensory threshold 3. distinctive electrographic signs |
| Vertebrates/Vertebrates | quiet resting behavior, typical body position, reduced reactivity to environmental stimuli and relative rapid reversibility of these states. |
| Birds/reptiles/mammals | sleep and wakefulness further assessed by dynamic changes in brain activity. |
| early sleep | decreases in body temperature, blood pressure, heart rate, and respiratory rate |
| Monophasic vs. polyphasic sleep | one major difference difference in human and rodent sleep is the distribution of sleep/wakefulness across the 34-hour day most species have polyphasic (throughout day) sleep monophasic- one chunk of sleep |
| measures of human sleep | Electroencephalogram (EEG)-wavelengths of brain Electromayogram (EMG)-wavelengths of muscles Electroculogram (EOG)- measures of eye movements Autonomic system measures |
| What does EEG measure? | summated potentials of a large cortical neuron group Alpha activity Beta activity Theta activity Sleep spindles k complexes Delta activity |
| stages of sleep | REM- beta Stage 2- nonrem-spindle/k complex awake- low voltage, high frequency alpha/beta stage 1-nonrem, theta rhythm stage 3- nonrem-deltas stage 4- nonrem/delta |
| NREM | characterized by a change in the EEG from a low-amp, high-freq to high-amp, low freq pattern |
| stage one | characterized by relatively low amp theta frequency activity (4-7 cycles per second) and vertex sharp waves in the EEG |
| stage two | appearance of distinctive sleep spindles (lasting between .5 and -1.0 seconds, peak amp 100 IV) EEG slowing down |
| stage three | sleep spindles/k-complexes, characterized by the addition of high amp slow waves with no more than 50% of EEG record occupied by the slow waves. |
| stage four | the EEG record is dominated by high-amp and slow waves |
| slow wave sleep or delta sleep | stages three and four |
| REMS | bursts of saccadic eye movements appear in EOG and give State REM name |
| Activated sleep/paradoxical sleep | REM |
| Field potentials in the pons, lateral geniculate nucleus and occipital cortex spikes | activate occipital cortex- dreaming/visual sensations since visual cortex is being stimulated pons- lateral geniculate nucleus-occipital cortex |
| SWS | Delta is known to be generated thorough synchronized rhythmic thalamocortical circuit activity |
| Dreaming | occur both during SWS or REM sleep During REM- dreaming takes 80-90%, narrative story like dream, generally REM dreams are longer and more visual, more bizarre and not as related to actual life events During SWS- images, sometimes nightmares, night terr |
| Dreaming in SWS | NREM dreams tend to be shorter, more thoughtful, less emotional and more related to life events |
| Eye movements in dreams | follow patterns related to dream content or activity |
| Relationship between circadian rhythms and sleep cycles | Process S homeostatic: builds up during wakefulness (dependent on time awake) mechanisms are unknown Process C Circadian: 24 hour periodicity of sleep propensity |
| Chemical control of sleep | In dolphins sleep rebound is observed in the same hemipshere that has been sleep-deprived -one hemisphere sleep one awake - hemipshere that is deprived will rebound |
| Chemical control of wakefulness | neurotransmitters awake state: brain levels of - acetylcholine (Ach)--muscles - norepinephrine (NE)--depression - serotonin (5-HT)--depression - dopamine (DA)--depression - histamine (HA)--activating - glutamate (Glut)--most widespread in the brain |
| SWS-I | levels of Ach and Glut drop and remain at their lowest level until the end of SWS-II Levels of GABA in the cortical and subcortical areas of the forebrain slowly increase during SWS-I and then reach their highest levels during SWS-II |
| Jouvet experiment | transection of the parts of the brain, if you do that the animal never recovers wakefulness, animal always appears asleep, need brainstem to appear awake |
| wake promoting cell groups | 1. NE synthesizing (noradrenergic) cells in the locus coeruleus 2. 5-HT synthesizing (serotonergic cells in the raphe nuclei 3. Ach-synthesizing (cholinergic) cells in the PPT and LDT 4. Glut-synthesizing (glutaminergic) in the midbrain 5. DA syntheiz |
| Forebrain groups that promote wakefulness | Histamine containing cells in the tuberomammillary nuclei of the hypothalamus 2.hypocretin containing cells in the LH 3.**cholinergic cells in the basal forebrain (BF) 4.neuropeptide Y containing cells in the SCN 5.Glutamatergic cells in the VMPFC |
| Importance of the cell groups | NONE of these cell groups appears to be absolutely necessary for the generation and maintenance of wakefulness |
| Acetylcholine | antagonists: decrease signs of cortical arousal microdialasis: level of activity of animal is correlated with production of Ach in the cortex, striatum and hypocampus |
| Norepinephrine | increase in arousal by NE agonists has long been known (amphetamines) main structure LOCUS COERULUS in brain stem - this structure projects NE fibers to cortex, hippocampus, thalamus, cerebellar corex, pons, and medulla |
| LC | rate of firing seems to be related to level of attention of the animals. Performance in task was reduced after animal was tired so firing rate of NE neurons Seem to play a role in control of motor activity |
| Serotonin | origin: raphe nuclei in brain stem projection to all parts of the brain activation of raphe produces locomotion and cortical arousal pCPA produces reduction in cortical arousal not responsive to external activating stimuli that produce pain or stress |
| 5-HT | related to species specific behaviors, pacing, chewing, grooming when there is an orienting response then the activity of 5-HT diminishes function: suppressing processing of sensory information |
| Histamine | in the tuberomammallary nucleus projections mainly to cerebral cortex Produce increase of cortical arousal project of NE neurons and also arousal indirectly H1 agonists produce sleep and decrease wakefulness Mutant mouse: no effects on total sleep |
| Orexin/hypocretin: | cell bodies in lateral hypothalamus projections to areas of arousal wakefulness effects of O/H in all these areas facilitation of motor activity narcolepsy active waking/REM |
| Control of Arousal | Basal forebrain- achl neurons, afferents from hypocretin neurons tuberomammilary nucleus: histominergic neurons, afferents from hypocretin neurons Pons: ach neurons, afferents from hypocretin neurons Locus coerules: NE |
| Initiation of SWS II | active process |
| Preoptic area | POA, initation of SWS |
| Evidence | specific lesioning of cell bodies in POA of the anterior hypothalamus has been shown to effectively suppress SWS in mammals fMRI in rats |
| Adenosine | chemical control of initiation of sleep product of the metabolism of glycogen to glucose in gila cells that allows glia to provide extra nutrients to neurons |
| Caffeine | binds to adenosine receptors |
| Microdialysis | increase within basal forebrain during wakefulness and decreased during sleep |
| VLPA and adenosine | if VLPA is involved it needs to be activated by wahtever it is that produces activation in this region. adenosine is inhibitory, there is a need of indirect pathway |
| experimentally regional adenosine | produces activation of the VLPA, decreased activity of histaminergic neurons in tuberomammillary therefore increases SWS |
| VLPA projects to: | Tuberomamillary, dorsal pons, raphe, and LC (remember, these structures are related to arousal, therefore their inhibition is important for SWS). VLPA receives inhibitory information from the same areas that it inhibits: tuberomammillary raphe and LC |
| flip-flop | unstable, (e.g. in narcolepsy)difficulty in remaining awake when nothing arousing is happening |
| flip-flop model | hypocretin cells have the function of stablizing the system by promoting wakefulness and inhibitory sleep |
| Neural control of REM sleep | characteristics: desynchronized EEG, muscular paralysis, REMs, increased genital activiation, high cerebral metabolism and PGO waves |
| Transition to REM sleep | blocking of Slow waves and EEG spindles (voltage reduction) appearance of PGO waves Appearance of muscle atonia |
| PGO waves (pontine geniculate occipital) | 1st manifestation of REM originate in the Pons REM appears to be initiated in the pons, in group of Ach cells located around the brachium conjunctivism |
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