Lecture 6: Brain Arousal Systems Flashcards
What are the two parts of consciousness?
Arousal (being awake)
Awareness (conscious processing of inputs)
What parts of of consciousness is missing in a coma?
Arousal and Awareness
EEG shows nothing
What parts of of consciousness is missing in a persistent vegetative state?
Awareness (Arousal is present on EEG)
What has to be damaged in cerebral cortex to cause comatose state?
Bilateral and massive damage
Injuries to what areas often cause disruptions to consciousness?
Brainstem
Midbrain
Hypothalamus
What is the status of cortical neurons in a persistent vegetative state?
Hyperpolarized (30 mv below threshold)
What NTs take one from a coma to Arousal/Wakefulness?
Acetylcholine and EAA
Where can Acetylcholine be found?
Pedunculopontine Tegmental (PPT) Laterodorsal Nuclei (LDT)
Where can EAA be found?
Reticular Activating System (RAS)
Parabrachial Nuclei
Why is RAS not specific?
All sensory pathways converge at RAS and there is too much input - basically RAS is just an event detector
Where do the dorsal pathways go?
Go to intralaminar nucleus of thalamus and then diffuse to rest of the brain
Where do the ventral pathways go?
Skips thalamus via basal forebrain and hypothalamus and then diffuse to rest of the brain
Between RAS and Parabrachial Nuclei, which one utilizes ventral pathway only?
Parabrachial Nuclei
What happens if there is damage to PPT/LDT?
Severe Cognitive Defects
Slowing of Cortical processes
What NTs take one from Arousal/Wakefulness to Awareness?
Norepinephrine
Serotonin
What is the role of norepinephrine?
Startle and Alert (EEG Manifestation)
What is the role of serotonin?
Quiet Awareness
For arousal, what pathways are used?
Both dorsal and ventral
What NT takes one from Awareness to Alertness?
Dopamine
Where is dopamine found?
Ventral Tegmental Area
Substantia Nigra
What does dopamine do?
Cognitive Function
Motor Function
Emotion (pleasure)
How are oscillations created on EEG?
Dopamine + EAA release GABA???
What is affected in patients with Alzheimer’s?
Cholinergic systems: slow mental processes and impaired memory formation
What can treat some people in a persistent vegetative state
Levodopa
What causes spindle-like discharges during sleep?
Thalamocortical neurons are hyperpolarized and show occasional bursts
