Sleep

Nondeclarative Memory

NONDECLARATIVE MEMORY INVOLVES HOW TO DO THINGS: HOW TO RIDE A BIKE, HOW TO SURF AND IS FOSTERED OR PROMOTED BY REM SLEEP.

Sleep paralysis

A temporary condition in which a person is unable to move upon awakening in the morning or during the night.

Characteristics of Non-REM sleep

light, even respiration muscle control is present (toss and turn) Difficult to arouse from stage 4 SWS (resting brain?) Requires loud noise to awake person Groggy and confused if awaken

electrooculogram (EOG)

measures the electrical activity of the eyes

Sleep

A behavior and an altered state of consciousness. It is associated with an urge to lie down for several hours in a quiet environment. Few movements occur during sleep (eye movements).

Suprachiasmatic Nucleus

A cluster of neurons in the hypothalamus in the brain that governs the timing of circadian rhythms; contains a biological clock that governs some circadian rhythms + receives input from uamacrine/ganglion cells in the retina, a pathway that may account for the ability of light to reset the biological clock (zeitgeber function) + the intergeniculate leaflet of the lateral geniculate thalamic nucleus:This pathway may mediate the ability of other environmental stimuli to reset circadian rhythms (e.g. animals own activity) + Lesions here disrupt circadian rhythms +These cells may not require direct neural connections to control circadian rhythms, but may do using chemical signals

Eyes closed

Alpha activity (8-12 Hz) appears in the EEG record. Synchrony: high amplitude, low frequency waveforms.

Non-REM Sleep

Alpha, delta and theta activity are present in the EEG record. Stage 1 Stage 2: -Sleep Spindle: burst of waves of about 12-14 Hz -K complexes: spike, sharp waveforms, perhaps has an inhibitory mechanism promoting sleep. Stage 3-4: delta activity (synchronized), termed slow wave sleep (SWS), deepest stage of sleep.

Glycine

An amino acid; an important inhibitory neurotransmitter in the lower brain stem and spinal cord.

electroencephalogram (EEG)

An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.

Adenosine

An inhibitory neurotransmitter that plays a role in promoting sleep and suppressing arousal. The levels in the brain increase every hour an organism is awake.

SWS reflection

Assessment of SWS after Prolonged bed rest (no real changes in SWS) Mental activity increases SWS

Wakefulness

Beta activity/waves (13-30 Hz) = alert, which are present in the EEG record. desynchronous=they don't form a consistent pattern: high frequency (HIFI) and low amplitude

Sleep as restoration and repairing device

Brain activity is reduced during SWS (delta activity) Persons awakened from SWS appear groggy and confused Yet, exercise and forced bed rest have little effect on sleep

Neural Regulation of Arousal

Brain stem structures are important in arousal. Neurotransmitters involved: Norepinephrine (NE): locus coeruleus show high activity during wakefulness, low activity during sleep. (possibly used for watchfulness) Activation of ACh neurons produces behavioral activation and cortical desynchrony (high during REM, low during SWS) ACh agonist increase arousal, ACh antagonist decrease arousal 5-HT (sertonin): stimulation of the raphe nuclei induces arousal wheras 5-HT antagonist reduce cortical arousal

Beta waves

Brain-wave pattern associated with alert wakefulness., rapid brain waves; appear when a person is awake

Sleep deprivation

Can impair cognitive functioning: Perceptual distortions and hallucinations as well as impaired ability to concentrate have been reported during sleep deprivation. But sleep deprivation doesn't result in a physiological stress response nor does it interfere with normal bodily function. Animal studies: drastic health consequences of sleep deprivation. Rats that were forced to walk on rotating platform lose sleepSleep deprived rats exhibited increased eating and metabolic activity and eventually became ill and died

Measures of sleep

Electrophysiological instruments can be used in the sleep lab to assess the physiological changes that occur during an episode of sleep.

VENTRAL LATERAL PREOPTIC AREA

Group of GABA whose activity suppresses alertness and behavioral arousal and promotes sleep.LOCATED AROUND THE HYPOTHALAMUS IMPORTANT STRUCTURE FOR THE ONSET OF SLEEP TO INITIATE NONREM SLEEP. IF DESTROYED IN RATS, THEY HAVE DIFFICULTY GOING TO SLEEP DESPITE HOW SLEEPY THEY ARE.

Nature of clock cells

Hypothesis was that clock cells produced a protein that upon reaching a critical level, inhibited its own production Fruit fly: two genes per and tim control the production of two proteins: PER and TIM, eventually high levels of these proteins turn off the per and tim genes, resulting in declining levels of PER and TIM proteins, which in turn activates the two genes

The Pons

Important for the control of REM sleep. PGO waves = first predictor of REM sleep. ACh neurons in the pons modulate REM sleep. Increased ACh increases REM sleep. Pontine neurons fire at a high rate during REM sleep. Pontine lesions reduce REM sleep. Pontine ACh neurons project to the thalamus (control of cortical arousal), to the cortex (arousal and desynchrony) , and to the tectum (rapid eye movements) Pontine cells project via magnocellular cells within medulla to spinal cord: release glycine to inhibit alpha-motoneurons (induce REM motor paralysis or atonia)

Declarative Memory

Non-REM sleep is needed for this kind of memory. INVOLVES KNOWLEDGE OF EVENTS, FACTS, IN OTHER WORDS IT'S SEMANTIC (LEARNING IN SCHOOL) AND EPISODIC MEMORY (EVENTS). DECLARATIVE MEMORY = EPISODES AND LEARNING FROM SCHOOL. THIS IS FOSTERED OR PROMOTED IN STORAGE DURING NONREM SLEEP. THERE IS AN ADVANTAGE TO TAKING NAPS THROUGHOUT THE DAY.

Biological rhythms

Many of our behaviors display rhythmic variation SWS/REM cycles last about 90 minutes Daily rest-activity cycle is about 90 minutes Circadian rhythms ("about a day") One cycle lasts about 24 hours (e.g. sleep-waking cycle) Light is an external cue that can set the circadian rhythm Some circadian rhythms are endogenous (do not require light) suggesting the existence of an internal (biological) clock Monthly rhythms: Menstrual cycle Seasonal rhythms: Aggression, sexual activity

Mental activity in Sleep

Mental activity continues during sleep. Dreams occur during SWS and REM sleep. REM sleep: high levels of blood flow in the visual association cortex but low levels in the inferior frontal cortex REM eye movments resemble those made when a person scans a visual image

Electrophysiological instruments used for sleep

Mtone (EMG), Summated brain activity (EEG) and eye movements (EOG)

NAPTIME

RECENT STUDIES HAVE SHOWED THAT WHEN YOU TAKE A NAP, IT'S NON-REM SLEEP. THEIR DECLARATIVE MEMORY IS PROMOTED.

Patterns of sleep

REM and Non-REM

PGO waves

Pattern of high-amplitude electrical potentials that occurs first in the pons, then in the lateral geniculate, and finally in the occipital cortex, REM sleep is associated with a distinctive pattern of high-amplitude electrical potentials known as:, Waves of excitation that flow from the pons through the lateral geniculate nucleus of the thalamus to the occipital area and appear to initiate the EEG desynchrony of REM sleep.

REM Sleep

Presence of BETA activity (dysynchronized EEG pattern) Enhanced respiration and blood pressure Rapid eye movement (REM) Pontine-geniculate-occipital (PGO) waves Loss of muscle tones (paralysis) Vivid, emotional dreams Aroused by meaningful stimuli Person waking up from this stage feels rested

Seasonal Rhythms

SCN plays a role in governing seasonal rhythms Testosterone secretion in male hampsters shows an annual rhythm with increased secretion as length of day increases This annual rhythm is abolished by SCN lesions; lesioned hampsters secrete testosterone all year long Pineal gland interacts with the SCN to control seasonal rhythms The SCN projects to the PVN, which connects with the pineal gland which secretes melatonin During long nights, the pineal gland secretes high amounts of melatonin Lesions of the SCN, of the PVN, or of the neural connection between the SCN and PVN disrupt seasonal rhythms controlled by day length

Sleep stage cycles

SWS precedes REM sleep, we go from a heavy, deep sleep to a lighter, REM sleep right before we wake up. REM sleep lengthens over night. Basic sleep cycle = 90 minutes.

K complex

Single but large high-voltage spike of brain activity that characterizes stage 2 NREM sleep., Sharp, high-amplitude, negative wave followed by a smaller, slower, positive wave

Narcolepsy

Sleep appears at odd times Sleep attack: urge to sleep during the day Cataplexy: REM paralysis occurs, person is still conscious Sleep paralysis: REM paralysis that occurs just before or just after sleep Narcoleptics have reduced CSF levels of the specific neuropeptides

Sleep as an adaptive response

Sleep is noted in all vertebrates. The signs of REM sleep (muscle paralysis, EEG desynchrony, eye movements) occur in mammals. Did sleep evolve to keep our ancestors away from predators? Indus Dolphins sleep even though it's dangerous. These dolphins exist in muddy water and through natural selection have become blind because it served no purpose. Why then do they still sleep? If sleep has no function, why was it not lost?

1/3 of our lives is spent sleeping

This suggests the functionality of sleep

REM sleep reflection

Vigilance: alertness to the environment Consolidation of learning/memory (?) Facilitation of brain development: Infants spend more time in REM sleep

Nature of Consciousness during sleep

We experience some dreaming during sleep. We may recall very little of the mental activity that occurred during sleep. We may report details of dream during wakefulness.

Promotion of sleep

You need to dampen arousal so you must use ADENOSINE TO DAMPEN AROUSAL IN THE BRAIN (BAS = BEHAVIORAL ACTIVATION SYSTEM) (ADENOSEINE = PROMOTES SLEEP, YOU ACCUMULATE THIS AS THE DAY GOES ON. THE LEVELS OF ADENOSINE WILL INCREASE AS THE DAY GOES ON BUT IT VARIES FROM PERSON TO PERSON. THE THRESHOLD FOR THIS SLEEP PROMOTING CHEMICAL IS DIFFICULT).

electromyography (EMG)

a graphical record of electric currents associated with muscle contractions

Ventrolateral preoptic area (VLPA)

a group of GABAergic neurons in the preoptic area whose activity suppresses alertness and behavioral arousal and promotes sleep; important for the control of sleep. Lesions of the preoptic area produce total insomnia, leading to death. Electrical stimulation of the preoptic area induces signs of drowsiness in cats. These neurons promote sleep.

Theta waves

brain waves indicating the early stages of sleep: light sleep

Sleep spindle

brain-wave activity during Stage 2 sleep, 12- to 14-Hz brain waves in bursts that last at least half a second, A characteristic 14- to 18-Hz wave in the EEG of a person said to be in stage 2 sleep., sudden bursts of fast activity on the EEG (electroencephalogram)

Slow wave sleep

consists of sleep stages 3 and 4, during which high amplitude, low frequency delta waves become prominent in EEG recordings, non-REM sleep, characterized by synchronized EEG activity during its deeper stages, , sleep stages 3 and 4, which are accompanied by slow, deep breathing; a calm, regular heartbeat; and reduced blood pressure

Clock Cells

exhibit circadian rhythms in activity +glucose metabolism (2-DG method) is higher during the day than during the night +Each SCN cell appears to have its own clock (separate daily peaks in activity) Yet SCN clock cells act in a synchronized fashion (a chemical rather than a neural effect)

Atonia

no tone; condition of complete muscle inactivity produced by the inhibition of motor neurons

Orexin

plays a critical role in preventing abnormal consciousness transitions, particularly into REM sleep; may stimulate hunger, excitatory neurotransmitter that contributes to staying awake, prevents transition from wakefullness directly into rem sleep; A CHEMICAL USED FOR WAKEFULNESS (OREXIN = ERECTION) (WAKEFULNESS PROMOTING CHEMICAL) WE ACCUMULATE IT AS WE ARE ASLEEP TO WAKE US UP. IT REMOVES INHIBITION OF ADENOSINE ON THE AROUSAL SYSTEM. NOW YOU'RE INCREASING NE, DOPAMINE, AND 5-HT WHICH ARE IMPORTANT FOR WAKEFULESS.

Insomnia

refers to a difficulty in getting to sleep or remaining asleep and has many causes Situational Drug-induced: Use of sleeping pills can result in insomnia Sleep apnea: person stops breathing and is awakened when blood levels of carbon dioxide stimulate breathing

REM paralysis

the inability of the voluntary muscles to move during REM sleep

Delta waves

the large, slow brain waves associated with deep, dreamless sleep

Alpha waves

the relatively slow brain waves of a relaxed, awake state

Pons

used for the onset of REM sleep.