Session 7 - The Reticular Formation Flashcards
What is consciousness?
Difficult to define but something to do with ‘awareness’ of both the external world and internal states.
What is arousal?
The emotional state associated with some kind of goal or avoidance of something noxious
What two parts of the brain are required for consciousness?
Cerebral cortex and reticular formation
Where is the reticular formation located?
Brainstem
What inputs into the reticular formation regulate the level of arousal?
Sensory system
Cortex
Where do the outputs from the reticular formation lead to?
Thalamus (sensory gating)
Hypothalamus
Basal forebrain nuclei
Spinal cord (muscle tone)
Which part of the reticular formation is devoted to arousal?
The reticular activating system
What tool is used to asses consciousness?
Glasgow Coma Scale (GCS)
How else can consciousness be assessed?
Electroencephalogram (EEG)
The EEG activity seen in REM sleep is most similar to what other stage of consciousness?
Arousal/awake (beta waves)
Name some disorders of sleep.
Insomnia - mostly psychological causes rather than problems with the reticular formation.
Narcolepsy - rare. Problems with neurotransmission in the reticular formation system, can’t maintain wakefulness.
Sleep apnoea - obstruction of airway during sleep, woken up due to hypoxia.
Name some disorders of consciousness.
Brain death - widespread cortical and brainstem damage. Flat EEG.
Coma - widespread brainstem and cortical damage, with various disordered EEG patterns detectable. Unarousal and unresponsive to pyschological stimuli. No sleep-wake cycle detectable.
Persistent Vegetative State (PVS) - widespread cortical damage (reticular formation relatively spared), with various EEG patterns detectable. Like a coma but with some spontaneous eye opening. Can even localise to stimuli via brainstem reflexes. Sleep-wake cycle detectable.
Locked in syndrome - can by caused by basilar/pontine artery occlusion. Eye movement can be preserved, but all other somatic functions lost from the pons down.
