11a sleep and wakefullness

Reticular Activating System

Organization of Reticular Neurons

General Characteristics of RAS

Noradrenergic and adrenergic neurons in the medulla and pons

Noradrenergic neurons in the pons

Dopaminergic neurons in the brain stem and hypothalamus

Serotonergic Cell Groups

Cholinergic Cell Groups

Cortico-Reticulo-Spinal Projections

Effects of stimulation of reticular formation on spinal reflexes

•Stimulation of the facilitory zone (+) (shown in green) of the reticular formation causes a dramatic increase in the patellar reflex as determined by EMG measurements,

•Marked suppression of this reflex follows stimulation of the inhibitory zone (-) (shown in red) of the reticular formation.

Pain Is Modulated by Descending Monoaminergic Projections

Arousal and Ascending RAS

The ascending connections of the reticular formation

The electroencephalogram measures electrical activity in the cerebral cortex.

Electrical stimulation of the reticular formation

Thalamic relay neurons have transmission and burst modes of signaling activity

Damage to Either Branch of the Ascending Arousal System May Impair Consciousness

Sleeping and Dreaming

The duration of sleep

The consequences of total sleep deprivation in rats

The Circadian Cycle of Sleep and Wakefulness

 Anatomical underpinnings of circadian rhythms

Stages of Sleep

Physiological changes in a male volunteer during the various sleep states

Neural Circuits Governing Sleep

Cortical regions whose activity is increased or decreased during REM sleep.

Thalamocortical Interactions

The patterns of activity of key cell groups during waking and slow wave and REM sleep

The major regions of the brain stem and forebrain involved in sleep control are shown in this sagittal section

Possible connections of the key neuronal groups that control REM sleep

Cellular Mechanisms that Govern Sleep and Wakefulness

Brainstem nuclei responsible Neurotransmitter involved Activity state of the brainstem neurons

WAKEFULNESS

Cholinergic nuclei of pons-midbrain junction

Acetylcholine Active

Locus coeruleus Norepinephrine Active

Raphe nuclei Serotonin Active

NON-REM SLEEP

Cholinergic nuclei of pons-midbrain junction

Acetylcholine Decreased

Locus coeruleus Norepinephrine Decreased

Raphe nuclei Serotonin Decreased

REM SLEEP ON

Cholinergic nuclei of pons-midbrain junction

Acetylcholine Active (PGO waves)

Raphe nuclei Serotonin Inactive

REM SLEEP OFF

Locus coeruleus Norepinephrine Active

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