Study Guide: Chapter 8.docx

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PSY 351
Scott Wersinger

Chapter 8 1) There is stage 1, stage 2 , stage 3, stage 4 and REM sleep. Stage 1: Transition between wakefulness and sleep : Firing of neurons become more synchronized (Theta activity) Stage 2: EEG is irregular : Contain periods of theta activity, sleep spindles (in all stages) and K complex (only in stage 2) : Sleeping soundly but if awaken, it will feel as if one was not asleep Stage 3: Occurrence of high amplitude delta activity (20-50% delta activity) Slow-Wave Stage 4: More than 50% delta activity sleep : Deepest sleep stage REM sleep: Desynchronised EEG activity : Rapid eye movement & Person is “paralysed” during this stage 2) Electroencephalogram (EEG) measure the brain’s spontaneous electrical activity a. Electromyogram (EMG) measure muscle activity Alpha: Smooth & Synchronized b. Electroculogram (EOG) measure eye movement : 8-12 Hz Beta: Irregular : 13-30 Hz 3) Awake:Alpha activity followed by Beta activity Theta: Irregular : 3.5-7.5 Hz Delta: Regular & Stage 1: Theta activity Synchronized Stage 2: Periods of theta activity sleep spindles and K complex Stage 3 & 4: Delta activity REM sleep: Theta activity followed by Beta activity 4) Rapid-eye movement (REM) sleep is one of the stages of sleep that involves rapid eye movement and muscle paralysis. It is also a period of desynchronized EEG activity. 5) Brain region involved in arousal: 1. Reticular Formation (Medulla to Forebrain) 2. Pontomesencephalon (part of reticular formation) 3. Locus Coeruleus (Small structure in the pons) 4. Basal Forebrain axons (From Basal forebrain to thalamus and cerebral cortex) 5. Hypothalamus Neurotransmitter involved: 1. Acetylcholine a. Important for arousal b. Found in Pons & Basal Forebrain c. Increase = Increase EEG activity (Desynchronised activity) & Arousal i. When stimulated, moreAcetylcholine is released) d. Decrease = Decrease in EEG activity (in slow-wave sleep) 2. Norepinephrine a. Found in Locus coeruleus (located in the dorsal pons) which spread to the hippocampus, thalamus, cerebellar cortex, pons and medulla) b. Increase an animal’s vigilance c. Increase when awake and almost zero during REM sleep 3. Serotonin a. Almost all are found in the Raphe Nuclei (in Medullary and Pontin region of the reticular formation) b. Stimulation of Rap nuclei cause locomotion and cortical arousal c. Most active during waking and decline during sleep 4. Histimine a. Located in Tuberomammillary nucleus (TMN) of the hypothalamus b. The projection to the cerebral cortex directly increase cortical activation and arousal c. The projection to theACh neuron in the basal forebrain indirectly increase the release of acetylcholine 5. Orexin a. Located in lateral hypothalamus project to cerebral cortex and all region involve in wakefulness and arousal b. Have an excitatory effect in all those regions 6) Brain region:Anterior hypothalamus (preoptic area) a. Most involved in control of sleep b. Ventrolateral preoptic area (vLPOA) i. Contain majority of “sleep” neurons Neurons: 1. Preoptic neurons (sleep neurons) a. When activated, it suppress the arousal neurons b. Secret the inhibitory neurotransmitter GABA send their axons to the five region involve in wakefulness and sleep c. Inhibiting those five region is a necessary condition for sleep 2. Adenosine a. Located in the Basal forebrain b. Increased during wakefulness and slowly decrease during sleep c. Infuse adenosine agonist into the vLOPAactivates neurons there which decrease the activity of histaminergic neurons that increase slow-wave sleep Flip-flop: The basis for establishing periods of sleep and waking a. Mutually inhibition b. Either the sleep neurons suppress the wakefulness neurons (To sleep) c. OR, the wakefulness neurons inhibit the sleep neurons (Arousal) d. **It can change state quickly thus it is maladaptive e. **Can be unstable i. Orexinergic neurons can stabilise it through their excitatory connection to the wakefulness neurons 7) REM sleep is controlled by a flip-flop. Brain region: Pons => Lateral geniculate => occipital wave (to visual cortex) Requires 5-HT andAch for REM onset and continuous Sublaterodorsal nucleus (SLD) contain REM-ON neurons that activates REM Ventrolateral periaqueductal gray contain REM-ON neurons that suppresses REM Both REM-ON and REM-OFF is mutually inhibitory and connected by means of GABAergic neurons When REM-ON is stimulated, regions with infused glutamate agonist elicit most of the elements of REM sleep When REM-OFF is stimulated, region receives excitatory input from orexinergic neurons of the lateral hypothalamus and noradrenergic neurons of the locus coeruleus and the serotonergis neurons of the raphe nucleiwhich “switch off” the REM sleep. 8) Insomnia: The inability to get sleep SleepApnea: Inability to breath during sleep thus waking up from lack of breath Narcol
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