Sleep and Circadian Rhythms Flashcards
Recall that electroencephalograms measure the electrical activity of large populations of neurons
Electroencephalograms measure synchronous, electrical activity from large populations of neurons in the brain
Explain why electroencephalograms have high temporal- but low spatial resolution.
-High temporal resolution necessary to resolve the rapidly changing patterns of brain activity that underlie mental function
-Low spatial resolution because of the blurring effects of the head volume conductor and poor signal-to-noise ratio
Describe the differences in the four stages of non-REM sleep
Stage 1 (drowsiness)
-Awakened easily
-Eyes move slowly, muscle activity slows
Stage 2 (light sleep)
-Eye movement stops
-Body temperature drops
-Heart rate slows
-Brainwaves slow, occasional burst of rapid brain waves
-Bursts of sinusoidal waves, “sleep spindles”
-Biphasic waves called K complexes
Stage 3 (deep sleep)
-Slow delta waves with smaller faster waves
-Sleepwalking, sleep talking, bedwetting occurs during non-REM to REM transition
Stage 4 (very deep sleep)
-Exclusively delta waves
-If awoken from this stage, disorientation
Stage 5 (REM sleep)
-EEG mimics wakefulness
-Closed eyes, eyes move rapidly side-to-side
-Intense brain and dream activity
-Brain temperature and metabolic rate rise
-All skeletal muscles atonic (flaccid and paralysed)
-Diaphragm, eye, middle ear muscles remain active
Explain why REM sleep is paradoxical
Because it involves seemingly contradictory states of an active mind and a sleeping body, REM neuronal firing is similar to that in wakefulness
Explain the roles of the suprachiasmatic nucleus and the retinohypothalamic tract in circadian rhythms
-Sleep/wakefulness follow circadian rhythms (24hr)
-Major internal clock is suprachiasmatic nucleus of the anterior hypothalamus
-Suprachiasmatic nucleus regulates timing of sleep
-Retinohypothalamic tract connects the retina to the suprachiasmatic nucleus
