NSCI 175: Brain Rhythms and Sleep

How long may REM sleep periods last?

30-50 minutes

The external cue that animals use to discern the time of day is called a

zeitgeber

What part of the nervous system generates the fluctuations and oscillations of an EEG

dendrites of many pyramidal neurons in the cerebral cortex

What brain regions and associated neurotransmitters are implicated in changes associated with awakening and states of arousal?

A. Brain stem and forebrain (acetylcholine)

B. Raphe nuclei (serotonin)

D. Locus coeruleus (norepinephrine)

Why is REM sleep referred to as paradoxical sleep?

A. Vivid, detailed illusions called dreams are conjured during REM sleep

B. The EEG for REM sleep is almost indistinguishable from an active, waking brain

C. Rapid eye movements occur during REM sleep

D. The body (except for the eyes and respiratory muscles) is immobilized

B. The EEG for REM sleep is almost indistinguishable from an active, waking brain

The ________ ______ of the ______ requires input from the retina to maintain circadian rhythms that are in phase with the day-night cycle.

suprachiasmatic nucleus of the thalamus (SCN)

The time that elapses between two successive occurrences of a circadian event, such as the commencement of the day's activities, is called the

zeitgeber

period

entrainment

phase

period

Which of the following represents delta rhythms, the hallmark of deep sleep?

Greater than 14 Hz

4-7 Hz

8-13 Hz

Less than 4 Hz

Less than 4 Hz

What brain structure is known to act as a powerful pacemaker for the cerebral cortex?

Brain stem

Thalamus

Midbrain

Cerebellum

Thalamus

Which of the following describes REM sleep behavior disorder?

Dreamers with delta wave terrors

Sleepers who do not generate REM brain waves characteristic of REM sleep

Dreamers have no REM atonia and therefore may act out their dreams.

Sleepers who have narcolepsy

Dreamers have no REM atonia and therefore may act out their dreams.

What regulations of the body have been found to demonstrate a circadian rhythm? (3)

body temperature

hair growth

hormone secretion

EEG

Measure of multiple cerebral pyramidal neurons helps detect patterns in circadian rhythm through an electrodes

Awake EEG

Low voltage

Fast Vivid

Externally generated Logic

progressive

continuous

voluntary

REM: often

Non REM sleep EEG

high voltage, slow

involuntary

REM Sleep EEG

Low voltage

Fast vivid

illogical

bizarre

muscle paralysis

Awake amplitude and frequncy

low amplitude and high frequency rhythms

Deep non REM sleep amplitude and frequency

high amp, low frequency

Normal night we cycle through the stages of non REM and REM, repeating every

90 minutes

Four stages of non REM sleep

Transitional sleep (few minutes & lightest)

Slightly deeper (5-15 minutes)sleep spindles & K complex

Delta rhythms, deeper sleep

Deepest sleep (20-40 min)Slow large amplitude delta waves

Major connection in sleep between the __ and the __

excitatory:

hypothalamus and the cerebral cortex

Circadian rhythm vs ultradian rhythm

over 24 hours versus over a few minutes

Atonia, paradoxical sleep and sympathetic activation. fast low amplitudes, beta and gamma rhythms

REM sleep

beta and gamma rhythms

REM sleep

Delta rythmns

Non REM

Kidney function slows, parasympathetic, sleep spindle, K complex, four stages, reduced muscle tension

Non REM sleep

As we age our REM sleep and sleep

decreases

Babies will sleep more for shorter periods with more __

rem cycle

Why we sleep and consequence of sleep deprivation

Restoration: sleep to rest and recovery

Adaptation: hide from predators

Memory consolidation, prevents cognitive impairments

Inactivity Theory

Inactivity at night served as survival function to hide from predators

Energy Conservation Theory

sleep is an adaptation that allows us to conserve energy for gathering food, defeating predators

Brain Plasticity Theory

Changes in structure and organization of brain when we sleep.

Rerouting the neural circut

Restorative Theory

Restore elements impaired and depleted while awake

consequence of sleep deprivation

irritibility, emotional instability

increased heart rate

episodes of disorientation

Fatal Familial Insomnia (FFI)

Rare genetic disorder- Inability to sleep (starts off mild), but progressively worsens leading to significant physical and mental deterioration-

Abnormal variant in the prio-related protein (PRNP) located in the thalamus-

Prognosis: Death within 6-36 months after the onset of symptoms (no cure): spasms, can't eat, fever, rapid heart rate

Episodes of hallucinations.

Shorter sleep predicts

a shorter life because of diseases associated

Sleep deprived individuals have increased activity in the ___

amygdala

Increased Tau buildup causes

Alzheimer's, since sleep deprivation causes lack of filtering the brain

Increased firing rates in which of the following systems likely support the transition from sleep to wake? Select all that apply.

Histamine

Norepinephrine

Acetylcholine

Seritonin

Serotonin and NE enhance ____

5-HT & NE neurons fire during & enhance wake; Different ACh neurons enhance REM sleep while others enhance awake states

What do modulatory systems do to thalamus in sleep cycle

Systems control the rhythmic firing of thalamus which controls EEG rhythms of cortex (slow rhythms of sleep in thalamus block sensory information from reaching the cortex!)

What do modulatory systems do to our motor neurons

Descending branches of these systems inhibit motor neurons during dreaming!

REM on-cells

are cholinergic neurons in the pons that fire to enhance REM events

REM off-cells

include norepinephrine neurons in the locus coeruleus and serotonergic neurons in the raphe nuclei

which decrease firing to almost nothing during REM

Orexin

can excite neurons in modulatory systems

PROMOTES WAKEFULNESS: inhibit REM sleep

Hypocretin

a neurotransmitter secreted by cells in the hypothalamus; helps regulate sleep-wake cycles

Hypocretin is involved in

narcolepsy

narcolepsy is

when you dont go through slow wave sleep before REM,

Makes you sleepy in the day

Melatonin is released when

darkness rises

Melatonin

helps time when sleep will occur. It does not help when sleep occurs.

Helpful for jet lag.

Anti-Histamine promotes

promotes sleep

Caffeine

inhibits sleep signal.

Latches to adenosine sites and masks the receptors.

Once caffeine wears off, adenosine has build up

After ___ hours of being awake, you will start to feel sleepy

16

Zeitgebers:

environmental cues that signals the passage of time

For mammals: primarily light-dark cycle

suprachiasmatic nuclei (SCN)

in hypothalamus that function as a biological clock

suprachiasmatic nuclei (SCN) receives input from

photosensitive retinal ganglion cells, which allows them to reset the circadian clock

Lesions to the SCN abolishes

the circadian rhythms

Stimulating the SCN

shifts the circadian rhythms

Transplanting a SCN into a lesioned animal

restores circadian rhythms

In stage __ you have spindle and K complex

2

Stages 3 and 4 have ____ rhythms

delta