Reticular Activating System Wakefulness Sleep 2152022 retuclar activating

Reticular Activating System Wakefulness & Sleep 2/15/2022 retuclar activating system 1

Reticular Formation n Contain areas concerned with – Regulation of HR, BP, respiration n Some descending fibers – Inhibit sensory transmission at spinal cord level 2/15/2022 retuclar activating system 2

Reticular Activating System n Extends through out the brain stem – Mesencephalon – Pons – Medulla 2/15/2022 retuclar activating system 3

Reticular Activating System n Composed of diffuse conglomerate – Nerve cells – Axons of varying types and sizes n Intermingle – Form complex matrix 2/15/2022 retuclar activating system 4

Reticular Activating System n Two types of neurons – With axons ascending – With descending axons 2/15/2022 retuclar activating system 5

Reticular Activating System n The overall system that – Control the degree of CNS activity n Including – Wakefulness & sleep n Electrical stim of RAS – Causes a sleeping animal to awaken 2/15/2022 retuclar activating system 6

Reticular Activating System n Damage of these areas – Brain tumor, hemorrhage – Encephalitis lethargica n Causes coma – Loss of consciousness 2/15/2022 retuclar activating system 7

Reticular Activating System Activation of cerebral cortex n + + Thalamus – Provide intrinsic activity of the brain + n A + B Inhibitory Section of mid brain at “A” – Causes cerebrum to be inactive Excitatory Sensory inputs, touch, pain, temp 2/15/2022 Function of RAS of mid brain n Areas in brain stem – Below mid brain – Excite the activating system retuclar activating system 8

Reticular Activating System Activation of cerebral cortex n + + Thalamus + – Cerebrum remains active A + Excitatory B Inhibitory Sensory inputs, touch, pain, temp 2/15/2022 Section at mid pontine region at “B” n Areas in brain stem – Below mid pons – Can inhibit the activating system retuclar activating system 9

Reticular Activating System Activation of cerebral cortex + n + Thalamus Stimulation of RAS – Leads to wakefulness + A + Excitatory n Inhibition of RAS – Leads to sleep B Inhibitory Sensory inputs, touch, pain, temp 2/15/2022 retuclar activating system 10

Neuro-Humoral Control To thalamus & cerebrum Substantia Nigra Gigantocellular nucleus n Cerebellum Locus ceruleus Raphe nucleus To spinal cord 2/15/2022 Giganto-cellular nucleus – Medial portion of RF – Contain giant cells with • Ascending & descending axons – Principal activator of RAS • Use Ach retuclar activating system 11

Neuro-Humoral Control To thalamus & cerebrum Substantia Nigra Gigantocellular nucleus n Cerebellum Locus ceruleus – Anterior portion of midbrain – Project to wide areas • • Raphe nucleus To spinal cord 2/15/2022 Substantia nigra Basal ganglia Hypothalamus Cerebral cortex Limbic system – Use dopamine retuclar activating system 12

Neuro-Humoral Control To thalamus & cerebrum Substantia Nigra Gigantocellular nucleus n 2/15/2022 – Bilateral beneath 4 th ventricle – Has wide projection Cerebellum Locus ceruleus • Thalamus, cerebrum, RF, cerebellum Raphe nucleus To spinal cord Locus ceruleus n Stimulation of this area retuclar activating system 13

Neuro-Humoral Control To thalamus & cerebrum Substantia Nigra Gigantocellular nucleus n Cerebellum Locus ceruleus Raphe nucleus To spinal cord 2/15/2022 Stimulation of this area – Important in maintaining activity of RAS n Median raphe nucleus – In lower pons & medulla retuclar activating system 14

Neuro-Humoral Control To thalamus & cerebrum Substantia Nigra Gigantocellular nucleus n Cerebellum Locus ceruleus Raphe nucleus Neurons send fibers to – Thalamus, cerebrum, spinal cord – Uses serotonin 5 HT as transmitter To spinal cord 2/15/2022 retuclar activating system 15

Neuro-Humoral Control To thalamus & cerebrum Substantia Nigra Gigantocellular nucleus n Cerebellum Plays an inhibitory role – Essential for sleep inducing Locus ceruleus Raphe nucleus To spinal cord 2/15/2022 retuclar activating system 16

Brain Waves Frontal Pre-central n Parietal – EEG Occipital n 2/15/2022 Recorded by electroencephalogr am Continuous electrical activity retuclar activating system 17

Brain Waves Frontal Pre-central n Parietal Intensity and pattern – Determined by overall activity of brain Occipital n Intensity varies – From 0 to 300 v n Frequency varies – From 1 to 50 cps 2/15/2022 retuclar activating system 18

Brain Waves Frontal Pre-central n Parietal Characteristic of the waves – Highly dependent on activity of the brain Occipital n Waves change during state of – Wakefulness or – Sleep 2/15/2022 retuclar activating system 19

Brain Waves 8 – 13 cps n – 50 v – 8 – 13/sec Waves 18 – 30 cps Theta Waves 4 – 7 cps Delta Waves <4 cps 2/15/2022 Alpha waves n Found in EEG of normal person – Awake & quiet resting state – Most intense in occipital region retuclar activating system 20

Brain Waves 8 – 13 cps Waves 18 – 30 cps Theta Waves 4 – 7 cps – Disappear during sleep – Visual sensation causes immediate cessation of waves Delta Waves <4 cps 2/15/2022 retuclar activating system 21

Brain Waves 8 – 13 cps n Waves 18 – 30 cps n – 18 – 30/sec Theta Waves 4 – 7 cps Delta Waves <4 cps Beta waves Mostly recorded from – Parietal – Frontal n Found in EEG of a person during – Activation – Tension 2/15/2022 retuclar activating system 22

Brain Waves 8 – 13 cps Waves 18 – 30 cps n – 4 – 7/sec n Theta Waves 4 – 7 cps Delta Waves <4 cps 2/15/2022 Theta waves Recorded mainly in – Parietal – Temporal n Found in EEG of children retuclar activating system 23

Brain Waves 8 – 13 cps Waves 18 – 30 cps Theta Waves 4 – 7 cps Delta Waves <4 cps 2/15/2022 n Also occur in EEG of some adults under – Emotional stress – Disappointments – Frustration retuclar activating system 24

Brain Waves 8 – 13 cps Waves 18 – 30 cps Theta Waves 4 – 7 cps Delta Waves <4 cps 2/15/2022 n Delta waves – < 4/sec n Occur in EEG – During deep sleep – In infancy – In serious organic brain diseases retuclar activating system 25

Wakefulness & Sleep n Circadian periodicity n Living things undergo rhythmical changes – Organs – Functions n Changes are coupled – To 24 hrs periodicity – Associated with earth’s rotation 2/15/2022 retuclar activating system 26

Wakefulness & Sleep n Causes of rhythmicity n Endogenous processes – Biological clocks n Endogenous periodicity – Correspond only approximately (circa-) – To duration of day (dies) • Circadian rhythm 2/15/2022 retuclar activating system 27

Wakefulness & Sleep Circadian periodicity in humans n Many parameters of human n – Organs – Functions n Change cyclically – With a 24 hrs period • Body temperature • Waking & sleep cycle • Secretion of certain hormones 2/15/2022 retuclar activating system 28

Sleep Phenomenon n Sleep is a state of – Unconsciousness – From which a person can • Easily be aroused by • Appropriate stimuli n Compare to – Anaesthesia – Coma 2/15/2022 retuclar activating system 29

Sleep Phenomenon n During sleep individual contact – With environment – Very much restricted 2/15/2022 retuclar activating system 30

Sleep Phenomenon n Sleep is – Age associated phenomenon – New born babies • Sleep most of time – Duration of sleep • Decreases after 1 yr – Adults sleep • 7 – 8 hrs/day – Older people • Enjoy naps frequently 2/15/2022 retuclar activating system 31

Sleep Phenomenon n Types of sleep – Slow wave sleep (SWS) – Rapid eye movement sleep (REM) n Slow wave sleep – Normal sleep – Brain waves are very slow 2/15/2022 retuclar activating system 32

Sleep Phenomenon n Restful sleep associated with – Peripheral vascular tone – BP, HR, RR, BMR – Mean venous PCO 2 , and arterial PCO 2 – Arterial PO 2 2/15/2022 retuclar activating system 33

Sleep Phenomenon n SWS is also associated with – Talking in ones sleep – Sleep walking – Night terror – Dreams , usually not remembered 2/15/2022 retuclar activating system 34

Stages of Sleep n Awake state – Characterized by -waves n Drowsy state – Characterized by -waves n Stage 1, characterized by • Low voltage waves, with sleep spindles 2/15/2022 retuclar activating system 35

Stages of Sleep n Stages 2 & 3 characterized by – Theta waves n Stage 4 characterized by – Waves – Slow wave sleep 2/15/2022 retuclar activating system 36

Stages of Sleep n REM sleep – From stage 4 one enters into – REM sleep – Characterized by -waves 2/15/2022 retuclar activating system 37

Lesions A B Red nucleus Midbrain Vestibular nucleus Pontine Ret. formation Medulla oblongata 2/15/2022 Medullar Ret. formation C retuclar activating system 38