CH. 5 Sleeping, waking, and circadian rhythms

PSYC 305 Brain and Behavior

Circadian rhythm

24-hour cycle that regulates our sleeping and waking phases

Zeitgebers

• German time-givers

• Are external cues that help us know the time (sunlight, temperature, sounds)

Superchiasmatic nucleus (SCN)

Uses light information to regulate our internal sense of time

Circadian factor

Our endogenous biological clock and external cues; control our circadian rhythm

Homeostatic factor

Our body’s natural attempt for homeostasis; control our circadian rhythm

Homeostasis

How body system regulates and maintains themselves

Electroencephalogram (EEG)

Records the brain’s electrical activity (brain waves)

Electrooculogram (EOG)

Records eye movement using electrodes near the eyes

Electromyogram (EMG)

Records electrical activity from muscle fibers when muscles contract

Frequency

Number of cycles within a specific time frame

Amplitude

The height of each wave

Synchronized EEG

Neurons fire synchronously, producing brain waves with high amplitude and low frequency; happens when person is drowsy

Desynchronized EEG

Neurons fire asynchronously and produce brain waves with low amplitude and high frequency; happens when person is alert

Beta waves

Seen during alert wakefulness, desynchronization of EEG recordings

Alpha waves

Relaxation increases, and EEG shows increased amplitude

Stage 1 of sleep

• Light sleep; transition between awake and asleep

• Grouped with stage 2; slightly deeper

Stage 3

• Delta waves

• Deep sleep, slower frequency, and higher amplitude

• Slow-wave sleep

REM sleep

Dreaming occurs, sympathetic nervous system active, muscle atonia makes up temporarily paralyzed so we do not act out our dreams

The sleep cycle

• We cycle through several times each nigh

• Stage 3 is highest in 1st cycle, and decreases each additional cycle

• REM sleep increases with each cycle

• Each cycle lasts about 90 minutes

The fetus spends all its time in _____ before birth

REM sleep

REM sleep is only observed in ____ and _____

Birds; mammals

_____ do not exhibit REM sleep

Aquatic animals

_____ and ______ can sleep in one hemisphere while staying awake in the other

Killer whales; dolphins

Posterior cortical areas and the brainstem show _____ during REM sleep

Strong activation

Posterior parietal lobe

Attention, spatial and sensory integration

Frontal regions usually inactive, unless during:

Lucid dreaming

Thalamus job during waking

Generates by sending excitatory signals to the entire cortex

Deep brain stimulation:

Using electrodes to electrically stimulate the brain

Intralaminar nucleus

Region where minimal consciousness is exhibited by temporary alerts from stimulating the central thalamus

Neurotransmitters that promote wakefulness

Serotonin, norepinephrine, histamine, orexin, acetylcholine

Adenosine

This neurotransmitter accumulates during wakefulness to promote sleepiness and activation of “sleep-on” neurons

GABA

Released from the preoptic area to initiate sleep by inhibiting “waking-on” neurons

Stimulate drugs

Can enhance the activity of “waking-on” neurons (nicotine, amphetamines)

_____ blocks adenosine to stop the sleepy feeling

Caffeine

Clock gene

Molecular components for our internal clock

What did experiments using cat brains reveal about the brain stem during REM sleep

When the forebrain (cortex and thalamus) are disconnected from the pons, there is no REM sleep. If the cut was placed posterior to the pons, REM sleep was mostly normal.

When the ____ is lesioned muscle paralysis during REM sleep is lost

Pons

What causes sleep paralysis

Pons sends axons to the medulla, which inhibit spinal cord neurons

Insomnia

Inability to fall asleep and/or sleep through the night, caused by stress, anxiety, pain, caffeine, or enviromental factors

Medications for insomnia

Melatonin, antihistamines, hypnotics (benzodiazepines)

Benzodiazepines

Cause muscle relaxation and anti-anxiety effects

Target GABA-A receptors to inhibit waking-on neurons

Symptoms: Cataplexy (loss of muscle tone), sleep paralysis (inability to move upon waking or falling asleep), hypnagogic hallucinations (sensory hallucinations upon waking or falling asleep

Narcolepsy

Excessive, sometimes irresistible daytime sleepiness

May be a malfunction of REM sleep and orexin receptors

Medication(s) for narcolepsy

Stimulant drugs

Sleep apnea

Disruption of breathing during sleep

Loss of oxygen leads to poor sleeping and daytime fatigue

Snoring is a common symptom

REM sleep behavior disorder

Muscle paralysis does not occur

Likely related to a disruption in the pons

More likely to act out dreams

Treatment for sleep apnea

CPAP machine (continuous positive airway pressure)

Treatment for REM sleep behavior disorder

Options are limited