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__ evokes fear and feelings of punishment and aversion

periventricular nuclei


sexual arousal from __ of the hypo-thalamus

most anterior and most posterior portions


o cycles of periodicity shorter than 24 hours
o examples: heart

Ultradian Rhythms


- cycles of periodicity longer than 24 hours
- examples: menstrual cycle, gestation

Infradian Rhythms


- cycles of periodicity that approximate Earth's rotational period (24-hour day)
- examples: sleep-wake cycle, hormone levels

Circardian Rhythms


• regulate activity of many physiological processes including heart rate, blood pressure, body core temperature and blood levels of hormones
• external environmental clues influence strict 24-hour cycles

Biological Clock


• implicated in regulation of circadian rhythms
• secretes a hormone called melatonin that is synthesized from serotonin
o increased during darkness
o inhibited by daylight
o controlled by sympathetic nerve activity, which is regulated by light signals from the retina

Pineal Gland


• also known as jet lag
• physiological condition which results from altera-tions of circadian rhythms
• when traveling across time zones, body clocks will be out of synchronization with the destination time - due to experience of daylight and darkness contrary to accustomed rhythms
• treated with melatonin or sunlight exposure



• unconsciousness from which the person can be aroused by sensory or other stimuli



Types of Sleep

• Slow Wave Sleep / Non-REM Sleep
• Rapid Eye Movement (REM) Sleep


- deep, restful type of sleep
- characterized by decreases in periph-eral vascular tone, blood pressure, respiratory rate and metabolic rate
- frequently called dreamless sleep
- however, dreams and sometimes even nightmares do occur during slow-wave sleep

Slow Wave Sleep / Non-REM Sleep


- called paradoxical because the brain is active and skeletal muscle contractions occur
- lasts 5 to 30 minutes
- repeats at 90 minute intervals
- may be absent in extremely tired individuals

Rapid Eye Movement (REM) Sleep


Important Characteristics of REM sleep

• active form of sleep associated with dreaming and active bodily muscle movements
• more difficult to arouse than slow-wave sleep
• muscle tone is exceedingly depressed
• irregular heart rate and respiratory rate (dream state)
• irregular muscle movements do occur
• brain is highly active in REM sleep
-- overall brain metabolism increased by 20 percent
-- EEG shows a pattern similar to wakefulness


• raphe nuclei in lower pons and medulla - most conspicuous stimulation area for causing almost natural sleep
• nucleus of the tractus solitarius
• diencephalon
- rostral hypothalamus (suprachiasmal area)
- diffuse nuclei of thalamus

Sleep Centers: Slow-Wave Sleep


What neurotransmitter is elaborated from raphe nuclei?



Which Cranial Nerves arse subserved by the nucleus tractus solitarius?

- Facial Nerve
- Glossopharyngeal Nerve
- Vagus Nerve


• drugs that mimic the action of acetylcholine increase the occurrence of REM sleep
• gigantocellular cells
• large acetylcholine-secreting neurons in the upper brain stem reticular formation
• postulated sleep center for REM sleep

Sleep Centers: REM sleep


Postulated Functions of Sleep

• neural maturation
• facilitation of learning or memory
• cognition
• conservation of metabolic energy
• restoration of natural balance among neuronal centers


• measures voltage fluctuations resulting from ionic current flows within neurons
• recording the brain’s spontaneous electrical activi-ty from multiple electrodes placed on the scalp
• diagnostic applications: epilepsy, coma, brain death

Electroencephalography (EEG)


Types of EEG Waves

- Alpha Waves
- Beta Waves
- Theta Waves
- Delta Waves


- rhythmical waves with a frequency of 8-12 Hz at about 50 mV
- found in normal, awake but resting (eyes closed) individuals
- disappear during deep sleep

Alpha Waves


- occur at frequencies of 14 to 80 Hz with voltage less than 50 mV
- recorded mainly from parietal and frontal regions
- occur when the eyes are opened in the light
- requires intact thalamocortical projections and ascending reticular input to thalamus

Beta Waves


- wave frequencies of 4 to 7 Hz
- occur mainly in the parietal and tem-poral areas in children but may appear in adults during emotional stress
- associated with brain disorders and de-generative brain states

Theta Waves


- all of the waves below 3.5 Hz
- occur during deep sleep, organic brain disease and in infants
- persist in the absence of cortical input from the thalamus and lower brain centers

Delta Waves


- fairly regular pattern of waves at a frequency of 8–13 Hz and amplitude of 50–100 V (alpha waves)
- most marked in the parietal and occipital lobes
- associated with decreased levels of attention

Alpha Rhythm


- alpha rhythm is replaced by an irregular 13–30 Hz low-voltage activity (beta waves)
- also called alpha block, arousal response or desynchronization
- produced by any form of sensory stimulation or mental concentration

Beta Rhythm


- lapsing abruptly into REM sleep from awake state
- sleep episodes last about 15 minutes without warning
- often triggered by a pleasurable event
- emotionally intense experience can also trigger cataplexy, a sudden loss of voluntary muscle control



- sleepwalkers arise from slow wave sleep in a state of low consciousness and perform activities that are usually performed during full consciousness
- little or no memory of the incident, as they are not truly conscious

Somnambulism / Sleep Walking


- chronic inability to obtain the amount or quality of sleep needed to function adequately during the day
- most common cause is psychological disturbance



- temporary cessation of breathing during sleep
- loss of muscle tone during sleep allows excess fatty tissue or other structural abnormalities to block the upper air-way
- associated with obesity and made worse by alcohol

Sleep Apnea