EEG Sleep Circadian rhythms Learning Objectives: 121, 122

EEG Sleep Circadian rhythms Learning Objectives: 121, 122 Zoltán Lelkes Electroencenphalography Hans Berger pen time amplifier electrodes 1

The waves of the EEG gamma > 30 Hz beta: 13-30 Hz Mental activity: + alpha: 8-13 Hz theta: 4-8 Hz Sleep spindle delta: 0.5-4 Hz - K complex 2

The waves of the EEG beta: 13-30 Hz alpha: 8-13 Hz Mental activity: + theta: 4-8 Hz delta: 0.5-4 Hz - Electroencephalography eyes open eyes closed 3

Characteristics of EEG activity change in different situations, 1. with the level of vigilance: alertness, rest, sleep and dreaming. 2. mental tasks also alter the pattern of the waves in different parts of the brain. 3. electroencephalograms are also used in neurology and psychiatry, to help diagnose diseases of the brain, such as epilepsy, sleep disorders brain tumors. The origin of EEG waves Slow electrical activity of neurons. Summed postsynaptic potentials of parallelly arranged pyramidal cells, 4

The origin of the EEG The origin of the EEG mv + - negativer pole Dipole - Pyramidal cell + + - -- - Afferent fiber EPSP positiver pole + - + + mv time 5

The origin of the EEG The origin of the EEG 6

The origin of alpha activity The origin of alpha activity Relay nuclei - + Nuc. reticularis thalami + Cortex 7

EEG synchronization and desynchronization Apical dentrit (DC) Thalamic afferent Efferent Resting state Activation EEG desynchronization and synchronization low amplitude high amplitude synchronized activity desynchronized activity afferent input 16 8

Epilepsy 9

Epilepsy Epilepsy 10

Evoced potential The topographic study of brain electrical activity was born again only when fast desktop computers became available in the 80s. Thus, EEG brain topography was developed. It is also called Color Brain Mapping. 11

BRAIN MAPING Brain Mapping 12

Magnetoencephalography MEG) Sleep 13

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Characteristics of sleep: How do we claim that somebody is sleeping? 1. Loss of conscioussness 2. Decrease (or loss ) in muscle tone 3. Change of respiration (rhythmic, slow, superficial) 4. Autonomic signs (blood presure, heart rate) 5. Cortical activity (EEG) 17

Non-REM sleep Sleep stages Slow waves in EEG Muscle tone, respiratory rate, heart rate, blood pressure, body temperature, metabolic rate decreases. stage 1. Flat EEG, theta waves stage 2. Sleep spindles, K complexes stage 3. Theta and delta waves stage 4. (delta sleep) Delta waves REM sleep (paradoxical sleep) Fast EEG, absence of muscle tone, PGO-waves, rapid eye movemenents Respiratory rate, heart rate, blood pressure fluctuates. erection Non-REM sleep Sleep stages Slow waves in EEG Muscle tone, respiratory rate, heart rate, blood pressure, body temperature, metabolic rate decreases. stage 1. Flat EEG, theta waves stage 2. Sleep spindles, K complexes stage 3. Theta and delta waves stage 4. (delta sleep) Delta waves REM sleep (paradoxical sleep) REM-sleep deep non-rem sleep Wakefulness Fast EEG, absence of muscle tone, PGO-waves, rapid eye movemenents Respiratory rate, heart rate, blood pressure fluctuates. erection 18

Non-REM sleep Sleep stages Slow waves in EEG Muscle tone, respiratory rate, heart rate, blood pressure, body temperature, metabolic rate decreases. stage 1. Flat EEG, theta waves stage 2. Sleep spindles, K complexes stage 3. Theta and delta waves stage 4. (delta sleep) Delta waves REM sleep (paradoxical sleep) Fast EEG, absence of muscle tone, PGO-waves, rapid eye movemenents Respiratory rate, heart rate, blood pressure fluctuates. erection wakefulness sleep spindle REM sleep Sleep stages 19

Non-REM sleep Sleep stages Slow waves in EEG Muscle tone, respiratory rate, heart rate, blood pressure, body temperature, metabolic rate decreases. stage 1. Flat EEG, theta waves stage 2. Sleep spindles, K complexes stage 3. Theta and delta waves stage 4. (delta sleep) Delta waves REM sleep (paradoxical sleep) Fast EEG, absence of muscle tone, PGO-waves, rapid eye movemenents Respiratory rate, heart rate, blood pressure fluctuates. erection The sleep during a night Sleep is entered through non-rem sleep. Non-REM sleep and REM sleep alternate with a period near 90 min. Slow wave sleep predominates in the first third of the night and is linked to the initiation of sleep, REM sleep predominates in the last third of the. 20

The distribution of sleep stages is dependent upon age Hours Awake Week Month Years % Time spent in sleep 50 40 30 20 10 0 4 5 6 7 8 9 10 11 h 21

Mortality rate and the length of sleep 2.5 2.0 1.5 1.0 4 5 6 7 8 9 10 11 óra Time spent in sleep 22

Characteristics of dreams: 1. visually dominated 2. irregular 3. irreal 4. bizarre 5. difficult to retrieve 6. periodic 7. emotional Biological role of dreams Freud model: People are driven by aggressive and sexual instincts that are repressed from conscious awareness. While these thoughts are not consciously expressed, they find their way into our awareness via dreams. Hobson concepts (lack of sensory information, PGO waves) 23

The 2 process model of sleep regulation sleep wake sleep wake Basal forebrain 24

1: encephale isolé 2: cerveau isolé Consequences of lesions Basal forebrain - insomnia Post. hypothalamus - sleepiness Mesencephalic form. ret. - sleepiness Transection in the pons - insomnia 25

Ascending Arousal System (Locus Coeruleus, Formatio Reticularis) NA, Ach The ascending arousal system. Adapted from Saper et al. Hypothalamic Regulation of Sleep and Circadian Rhythms. Nature 2005;437:1257-1263. 26

The posterior hypothalamus (histamin, orexin), the locus coeruleus, the mesencephalic formation reticular system and other brainstem regions contains cholinergic, monoaminergic (mainly noradrenergic) and glutamatergic wake-on neurons. The most important brain structures involved in the regulation of sleep-wake activity 27

The basal forebrain (specially the ventrolateral preoptic nucleus) and the anterior hypothalamus contains sleep-on neurons (GABA, galanin). Non-REM-on cells: in the anterior hypothalamus and the basal forebrain REM-waking-on cells: in the brain stem reticular formation REM-off cells: Noradrenergic, adrenergic, and serotonergic cells in the brainstem and histaminergic cells in the forebrain. REM-on cells. 28

Promotion of sleep and wakefulness 5-HT??? The activity of serotonergic cells increase in wakefulness. Depletion of 5-HT results in insomnia. 29

REM sleep Cholinergic REM-sleep promoting mechanism DR LC - - 5-HT NE + + - - + ACh REM-sleep PONS Cholinerg structures: Nucl. Gigantocellularis Nucl. reticularis 30

Acetilcholine REM sleep Wakefulness REM sleep Glutamatergic REM-sleep promoting mechanism Model of the network responsible for PS. DPGi dorsal paragigantocellular reticular nucleus, ddpme dorsal deep mesencephalic reticular nucleus, DRN dorsal raphe nucleus, GiV ventral gigantocellular reticular nucleus, Gly glycine, Hcrt hypocretin (orexin)-containing neurons, LC locus coeruleus, vlpag ventrolateral periaqueductal gray, SLD sublaterodorsal nucleus 31

Lack of Hyporectin (Orexin) Narcolepsia Melatonin Adenosine VIP,Prolactin Orexin Cytokins NO CCK ACh NA - decreases sleep threshold - increase non-rem sleep (coffeine: receptor blocker) - increases REM sleep - increases wakefulness - increases sleep,mainly non-rem sleep - basal forebrain: non-rem brainstem:rem - increases non-rem sleep - increases wakefulness (basal forebrain) increases REM sleep (brainstem ) -increases wakefulness 32

Regulation of melatonin production The circadian rhythm under normal conditions and in isolation Natural lightdark rhythm A zeitgeber is any external or environmental cue that entrains, or synchronizes, an organism's biological rhythms to the Earth's 24- hour light/dark cycle. Minimum of body temperature Time 12 h light 12h dark Isolation from the zeitgeber Alvás ébrenlét Sleep Wakefulness 33

The suprachiasmatic nucleus, or internal pacemaker, is responsible for regulating the body's biological rhythms. Cortex Unspecific thalamus Lateral hypothalamus Pontine reticular formation Locus coeruleus Dorsal raphe Laterodorsal temental nucleus Suprachiasmatic nucleus 34