Reticular Activating System - stimulation and lesion

what does a lesion of the locus ceruleus result in?

alters the induction of paradoxical or REM sleep

What is the effect lesions in the breathing control nuclei?

central sleep apnea Ondine's curse altered patterns of breathing in comatose patient sudden onset central apnea hypersomnia

What results when the six discrete nuclei of the raphe system are lesioned (trauma, infarction, hematomas, tumors)?

coma, these lesions are localized to the reticular formation in the midbrain and pons

What is the reticular activating system important for?

controls sleep, respiration, and circulation. monitors and adjusts all sensory information and outgoing command signals. Alterness

sudden onset central apnea

herniation of the tonsils of the cerebellum may cause medullary compression and induce this

What is decerebrate rigidity?

hyperextension of the legs, arms, and neck. hyperpronation of the arms. removes the tonic inhibition of the pontine reticulospinal tract and the lateral vestibulospinal tract, leading to a net excitatory effect on extensor motor neuron pool

Stimulation of the ARAS activates?

hypothalamic and behavioral responses particularly to pain and activates cortical neurons

Where is the lesion in decerebrate rigidity?

in the brain stem at the intercollicular level (midbrain)

what does electrical stimulation of the other six discrete nuclei of the raphe system?

induces arousal, these areas are involved in sleeps

How is speed controlled in the cuneiform nucleus?

intensity of stimulation

hypersomina

involves the midbrain reticular formation are are characterized by slow respiration and EEG indicative of sleep

What does electrical stimulation of the raphe magus result in?

produces strong and lasting analgesia

Ondine's curse

rare neurological condition causing failure of automatic respiration so that patients no longer breathe unless they consciously and voluntarily force themselves to do so

how do the multiple systems in the locus ceruleus contribute to the reticular system?

the balance of noradrenergic to the serotonergic pathways from the raphe nuclei may have an important role in sleep stages, depression, mania. they increase their activity in response to new and challenging stimuli. they may serve to focus attention by inhibiting any system that might otherwise be distractive