Biological Rhythms a types of biological rhythms b

Biological Rhythms a. types of biological rhythms b. neurohormones Sleep a. functions of sleep b. measuring sleep c. dreaming d. neural mechanisms e. sleep disorders

Biological rhythms 1. Circannual 2. Infradian 3. Circadian (Latin: Circa = “around”, dian = “day”) – Zeitgeber: “time giver” – Entrainment: alignment of rhythm with external cues e. g. , suprachiasmatic nucleus and sunlight

Biological Rhythms a. types of biological rhythms b. neurohormones Sleep a. functions of sleep b. measuring sleep c. dreaming d. neural mechanisms e. sleep disorders

Biological Clocks – Suprachiasmatic nucleus • A nucleus situated atop the optic chiasm responsible for organizing circadian rhythms. – Pineal gland • A gland attached to the dorsal tectum; produces melatonin and plays a role in circadian and seasonal rhythms.

Suprachiasmatic Nucleus – Part of hypothalamus – Damage disrupts rhythm.

Retinohypothalamic pathway

Pineal Gland – Rene Decartes Treatise of man (1640)- “principal seat of the rational soul” – releases melatonin (at night) – melatonin is derived from serotonin

Biological Rhythms a. types of biological rhythms b. neurohormones Sleep a. functions of sleep b. measuring sleep c. dreaming d. neural mechanisms e. sleep disorders

Functions of sleep • Universal phenomenon among vertebrates. • Only warm-blooded vertebrates (mammals and birds) exhibit REM sleep. • Essential to survival. • Improves memory. • Conserve energy resources. • Recuperate physically.

Sleep Deprivation • Restorative effects of sleep appear to be more important for brain than rest of body. • Deprivation does not appear to interfere with ability to perform physical exercise. • Cognitive abilities can affected by sleep deprivation. • Brain rests during slow-wave sleep. • Mental activity during the day increases slow-wave sleep at night.

Rebound phenomenon • REM sleep increases after a period of REM sleep deprivation.

Biological Rhythms a. types of biological rhythms b. neurohormones Sleep a. functions of sleep b. measuring sleep c. dreaming d. neural mechanisms e. sleep disorders

EEG 1. Frequency of the wave (n of peaks/unit time) – tells you about the number of cortical neurons generating EPSPs 2. Amplitude of the wave (height of wave) – tells us about the n of EPSPs that occur at the same point in time – n of neurons firing in synchrony

EEG Wave Types – Alpha activity • A smooth electrical activity of 8– 12 Hz recorded from the brain; associated with relaxation. – Beta activity • Irregular electrical activity of 13– 30 Hz recorded from the brain; associated with arousal. – Theta activity • EEG activity of 3. 5 -7. 5 Hz that occurs intermittently during early stages of slow-wave and REM sleep. – Delta activity • Regular, synchronous electrical activity of less than 4 Hz recorded from the brain; occurs during deep sleep.

Stages of Sleep – REM sleep • Desynchronized EEG activity during sleep; associated with dreaming, rapid eye movements, and muscular paralysis. – Non-REM sleep • All stages of sleep except REM sleep. – Slow-wave sleep • Non-REM sleep, characterized by synchronized EEG activity during deeper stages.

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Characteristics of REM sleep • • • low amplitude, high frequency desynchronous EEG rapid eye movement (REM) lower species show more REM sleep, as do human infants narrative dreams muscle atonia – motor cortex active but descending motor pathways paralyzed • penile erections and vaginal secretions • deepest stage? – incorporate things into our dreams – more likely to spontaneously awaken

Biological Rhythms a. types of biological rhythms b. neurohormones Sleep a. functions of sleep b. measuring sleep c. dreaming d. neural mechanisms e. sleep disorders

Sigmund Freud (1900) Interpretation of Dreams water = birth flying = sexual arousal knifes, swords = castration anxiety mud = feces cave, hallway = mother

Dream theories – Freud • Repressed memories and expression of libido. – Activation synthesis theory • Sensory experiences are fabricated by the cortex as a means of interpreting signals from the PGO activity. – Continual activation theory • Encoding of short term procedural memories into long-term memories.

Biological Rhythms a. types of biological rhythms b. neurohormones Sleep a. functions of sleep b. measuring sleep c. dreaming d. neural mechanisms e. sleep disorders

Sleep is not a passive process Cerveau isole • mesencephalon transection • continuous sleep Encephale isole • brainstem transection • permanent insomnia

Sleep/Waking “Flip-Flop” vl. POA= ventrolateral preoptic area ACh = acetylcholine NE = norepinephrine 5 -HT = serotonin

Ventrolateral Preoptic Area GABA neurons • Activation promotes sleep. • Destruction results in total insomnia.

Locus Coeruleus Norepinephrine neurons • Located in the pons near the rostral end of the floor of the fourth ventricle. • Involved in arousal and vigilance. • Decreased activity during sleep (both slow-wave and REM)

Locus coeruleus

– Acetylcholine • Cholinergic neurons located in the pons and basal forebrain produce activation and cortical desynchrony. – Serotonin (5 -HT) • Appears to play a role in activating behavior. – Histamine • Neurotransmitter that increases wakefulness and arousal; found in tuberomammillary nucleus of hypothalamus, just rostral to mammillary bodies. – Hypocretin (orexin) • A peptide produced by neurons whose cell bodies are located in the hypothalamus and project to arousal mechanisms; destruction causes narcolepsy.

Neural control of REM sleep – PGO wave (pontine, geniculate, occipital): • Bursts of phasic electrical activity originating in the pons, followed by activity in the lateral geniculate nucleus and visual cortex. – Peribrachial area • The region in the pons; contains acetylcholinergic neurons involved in the initiation of REM sleep.

Peribrachial area IC = inferior colliculus PPT = pedunculopontine tegmental n. LDT = lateral dorsal tegmentum

Biological Rhythms a. types of biological rhythms b. neurohormones Sleep a. functions of sleep b. measuring sleep c. dreaming d. neural mechanisms e. sleep disorders

Sleep Disorders – Insomnia • Affect approximately 25% of the population • No single definition of insomnia • May be a symptom of physical ailment. – Sleep apnea • Cessation of breathing while sleeping. • Can be mediated centrally or locally (obstructive). • May play a role in sudden infant death syndrome. – Narcolepsy • Disorder characterized by periods of irresistible sleep, attacks of cataplexy, sleep paralysis, and hypnagogic hallucinations. • Treat with stimulant medications.

– Cataplexy • Paralysis during waking. – Sleep paralysis • Paralysis just before a person falls asleep. – Hypnagogic hallucination • Vivid dreams that occur just before a person falls asleep; accompanied by sleep paralysis. – Nocturnal enuresis • Bedwetting – Somnambulism • Sleepwalking – Pavor nocturnus • Night terrors

Insomnia vs. Sleep Deprivation • • • 27 -year-old clinical psychologist on internship Gets up at 6: 30 AM Works and mothers all day Goes to bed about midnight She gets about 6. 5 hr sleep per night

Insomnia vs. Sleep Deprivation • 58 -year-old woman, who is married and whose husband has retired • Gets up at 8: 30 AM • Goes to church, reads, plays bridge • Goes to bed about 10: 00 PM -sleeps until 1: 30 AM -is “up and down” rest of night -finally gets out of bed around 8: 30 AM • She gets about 6. 5 hr sleep per night

Insomnia vs. Sleep Deprivation • Insomnia assumes adequate opportunity to sleep. • Sleep Deprivation -adequate ability to sleep -inadequate opportunity -generally sleepy, at risk for accidents • Insomnia -inadequate ability to sleep -adequate opportunity -generally not sleepy, though may report fatigue

Definitions of Insomnia • • • Difficulty falling asleep Difficulty maintaining sleep Waking up too early Nonrestorative or poor-quality sleep May have daytime impact

Insomnia primary cause - sleep medications - develop tolerance; REM rebound - we are poor estimators of how much sleep we get. treatments - Medications in short term - CBT in long term • 8 -10 wks to change poor habits and beliefs • sleep restriction, stimulus control, relaxation techniques, and education. • unfortunately, takes time and few practitioners

Medications • Use of hypnotics increased 60% from 2000 to 2006, at a cost of $45 billion per year.

FDA-Approved Medications • Benzodiazepines – – estazolam (Prosom) flurazepam (Dalmane) quazepam (Doral) temazepam (Restoril) – triazolam (Halcion) • Benzodiazepine Agonists – – – eszopiclone (Lunesta) zaleplon (Sonata) zolpidem (Ambien) • Melatonin Agonists – ramelteon (Rozerem)