Exam 3 Ch 10

Circadian rhythms

A pattern of behavioral, biochemical, or physiological fluctuation that has a 24-hour period.

Free-running period

When an animal is maintaining its own personal cycle without external cues and its a little longer then 24 hours long

Suprachiasmatic nucleus (SCN)

A small region of the hypothalamus that is an endogenous clock related to circadian rhythm

Specialized retinal ganglion cells

contain melanopsin (a photopigment that makes people sensitive to light). Most blind people don’t have these, so they are usually on free-running mode always

Transplant experiments & SCN

SCN contains an engoneous clock. Recipients of a donor's SCN will display the donor's SCN behavior

Retinohypothalamic pathway

The route which specialized retinal ganglion cells send their axons to the SCN

Melatonin

Pineal gland secretes this at night, this tells the brain day length

REM sleep

This stage of sleep is characterized by small-amplitude, fast EEG waves, completely relaxed muscles, and rapid eye movement. Vivid dreams, Motor neurons inhibited.

Desynchronized EEG

A pattern of EEG in a fully awake person that has a mix of many different high frequencies with low amplitude

Stage 3 sleep (slow-wave sleep: SWS)

Large amplitude, very slow waves called deltawaves which get weaker as the night progresses. Memory consolidation

Nightmares

long, frightening dreams that awaken the sleeper

Night terrors

Sudden arousal from stage 3 SWS marked by intense fear and autonomic reaction. Usually don't recall a vivid dream instead a feeling of being suffocated. Common in children

Change in sleep stages through lifespan (infant/adult/elderly)

Infant: Shorter sleep cycles. Much more REM sleep (half of sleep)

Adult: 20% of sleep is REM sleep

Elderly: much less SWS

Biological functions of sleep (understand differences between four functions described in book)

Energy conservation: we use less energy when asleep

Niche adaptation: being nocturnal or diurnal

Body and brain restoration: can clean out the brain

Memory consolidation: SWS helps memory consolidation

Basal forebrain

A region in the forebrain, ventral to basal ganglia, puts you into SWS

Reticular formation

Region of the brainstem that wakes you up from SWS. arousal system.

Pons

Important for REM sleep

Hypothalamus

“Coordinating center” of the basal forebrain, reticular formation, and pons for sleep

Narcolepsy

Sleep attacks that last 5-30 mins that occur at any time. Occurring several times a day.

Cataplexy

Sudden loss of muscle tone associated with narcolepsy. Leads to a collapse of the body while being conscious

Orexin

A “neuropeptide” in the hypothalamus is involved in switching between sleep states. People with narcolepsy have few or less of these.

Sleep paralysis

Inability to move or talk at right before or after (more likely) of sleep. Feels like something is crushing your chest. Lasts a few minutes.

REM behavior disorder

Someone will physically act out a dream, usually in older men and followed by parkinsons and dementia. From loss of paralysis during REM.

Insomnia

Difficulty falling asleep or remaining asleep. More common in older people, women, and drug users.

Sleep apnea

Poor respiration during sleep. Breathing could stop for a minute or so, or may slow drastically. Usually accompanied by loud snoring. Happens from throat relaxing and suffocating yourself.

Molecular Clock (general steps)

1. Proteins bind to DNA to promote transcription

2. Transcription of MrNA

3. Proteins made from MrNA bind to DNA inhibiting itself (during morning)

4. The proteins degrade over time

5. Repeat

Cycles through the night

Fewer SWS throughout the night (completely disappears). More REM through the second half of the night. You go through different stages throughout the night (REM-3 3-REM REM-2 2-REM)