Answer to Question 1
Answer: All vertebrates sleep. Sleep deprivation in humans can produce visual hallucinations and difficulty in concentration. During slow-wave sleep, brain activity declines, and it appears that slow-wave sleep is important for cognitive functioning. Although physical exertion (increase or decrease) has little effect on slow-wave sleep, mental exertion produces an increase in subsequent slow-wave sleep.
Answer to Question 2
Answer: Slow-wave sleep is produced by activity of neurons within the ventrolateral preoptic area (vlPOA), which act by inhibition of neural systems that promote wakefulness (e.g., NE within the locus coeruleus, histamine in the tuberomammillary nucleus, and serotonin within the raphe nuclei) to initiate sleep. When the sleep-waking flip-flop is in the awake state, sleep is prevented. In the sleep state, slow-wave sleep shifts to REM sleep via another flip-flop mechanism in which cells within the sublaterodorsal nucleus act as REM-ON cells while cells within the ventrolateral PAG act as a REM-OFF region. When the REM-ON cells are active, motor neurons of the spinal cord are inhibited, whereas tectal neurons generate rapid eye movements.
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Thoracic cage. Avoid heavy pressure over the sternum and xiphoid process; caution over rib cage.
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