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