PSYCH 115 Final UCLA

What are Biological Rhythms?

• regular fluctuations in a living process

• can vary in length or "period"

What are 3 types of biological rhythms?

1. Circadian

2. Ultradian

3. Infaradian

What is a Circadian rhythm?

• a 24 (ish) hour rhythm

• internal clock

What is an Ultradian Rhythm? (include examples)

• occurs more than once a day

• bouts of activity, feeding, and hormone release

What is an Infradian Rhythm?

• occurs less than once a day

• body weight, reproductive cycles

What does dinural mean?

active during the light/day

What does nocturnal mean?

active during the dark/night

Rhythms may be ___, __, or _.

behavioral, physiological, biochemical

What does Free-running mean?

• animal maintains its own cycle without external cues

• ex: no light

What is a Period (in rhythms)?

• time between two similar points on back-to-back cycles

• may not be exactly 24 hours apart

What is a Phase Shift?

• the shift in activity in response to a synchronizing stimulus

• ex: light or food

What is Entrainment?

the process of shifting a rhythm

What is the cue that an animal uses to synchronize with the enviroment?

• zeitgeber

• german for "time-giver"

Where is the biological clock located?

suprachiasmatic nucleus (SCN)

Where is the SCN located?

above the optic chiasm in the hypothalamus

What do SCN lesions do?

disrupt circadian rhythms

What can isolated SCN neurons do?

maintain electrical activity synchronized to the previous light cycle

What do we know about SCN transplants?

hamsters with SCN lesions that recieve a healthy SCN transplant (even if the period of the transplant is shortened) will restore circadian rhythms matching the donor's shortened period

What pathway sends light information from the eye to the SCN?

the retinohypothalamic pathway

What photopigment is found in ganglion cells from the retinohypothalamic pathway?

melanopsin

What two proteins do SCN cells make that together form a dimer?

Clock and Cycle

What does the Clock/Cycle dimer do?

promotes transcription of period (per) and cryptochrome (cry) genes, which then create a dimer

What does the Per/Cry dimer do?

inhibits transcription of Clock/Cycle genes

How long does it take for Per/Cry proteins to degrade?

approximately 24 hours

When melanopsin detects light what do their ganglion cells do?

release glutamate in the SCN

What does glutamate do in the SCN?

• entrains the molecular clock's day-night cycle

• promotes "Per" production

It is thought that "night owls" and "morning people" carry different versions of what genes?

the Clock and Period genes

In mice with a double mutation of the Clock gene, without a light-dark cycle what happens to their activity?

their activity shows no circadian rhythms

With no cues, how long is a human's free-running period?

• approximately 25 hours

• varies with age

What is sleep synchronized with?

• external events

• light and dark

We can entrain our sleep with what kind of stimuli? (4 examples)

1. lights

2. food

3. jobs

4. alarm clocks

In 77 days, how many nights of sleep did D5 get when isolated from time of day cues?

74

What does an Electroenceohalography (EEG) record?

electical activity in the brain

What does an Electro-oculography (EOG) record?

eye movements

What does an Electromyography (EMG) record?

muscle activity

What are electrical brain potentials used to classify?

• levels of arousal

• states of sleep

What is the EEG pattern found in an awake person called?

beta activity or "desynchronized EEG"

What type of sleep is divided into 3 stages that have characteristic activity patterns?

Non-REM sleep (NREM)

What type of sleep is defined by large amplitude, very slow delta waves?

Stage 3 (NREM3) or "Slow Wave Sleep" (SWS)

What type of sleep has EEG activity like an awake person but brainstem regions make muscles relaxed and limp?

Rapid-Eye-Movement Sleep (REM)

What is REM sleep characterized by? (3 examples)

• rapid eye movements under closed eyelids

• irregular breathing and pulse rates

• vivid dreams

What is REM sleep sometimes called due to the mismatch in brain activity and muscle activity?

paradoxical sleep

What are delta waves equivalent to?

deep sleep

What animal(s) does not show REM sleep?

Dolphins

• birds

What is different about SWS in dolphins and birds?

only one brain hemisphere enters SWS at a time

What does the difference in SWS allow dolphins and birds to do?

it allows them to continue functioning and moving while also resting

What are vivid dreams characterized by? (2 examples)

• visual imagery

• sense that the dreamer is "there"

What are nightmares?

frightening dreams that awaken the sleeper from REM sleep

What are night terrors?

• sudden arousals from NREM sleep

• marked by fear and autonomic activity

• occur within 2-3 hours of falling asleep

What is REM behavior disorder?

• lack muscle paralysis when sleeping

• allows them to thrash and act out their dreams

Some Sleep Statistics Questions (assume young adult)

1. How long is the average sleep time?

2. What percentage of sleep is stage 2 sleep?

3. What percentage of sleep is REM sleep?

4. How long do cycles last?

5. What type of sleep is seen more in early cycles?

6. What type of sleep is seen more in later cycles?

1. 7-8 hours

2. 45-50%

3. 20%

4. 90-110 minutes

5. Stage 3 or SWS

6. REM sleep

At puberty, your circadian rhythm shifts so that they get up _ in the day.

later

Later starts in high school programs improved ___ and ___ and reduced _ and __.

attendance, enrollment

depression, in-class sleeping

As you age, total time asleep and number of awakenings ___.

declines, increases

During infancy, essential stimulation used to develop and preserve neural pathways occurs during what type of sleep?

REM sleep (~50%)

At age 60, only half as much time is spent in _ as at age 20; by age 90 it has disappeared.

Stage 3

What are some effects of sleep deprivation? (3 examples)

• increased irritability

• difficulty concentrating

• episodes of disorientation

• compromises the immune system

• vary with age

What is fatal familial insomnia?

• inherited disease

• in midlife, people stop sleeping

• die 7-24 months after onset