Brain Arousal Systems - Karius 3/29 Flashcards
Describe persistent vegetative state
Physiologically identifiable sleep/wake cycles appear
No evidence of awareness
Describe minimally conscious state
Sleep/wake cycles
Reproducible evidence of awareness - ability to respond to simple commands
Limited/absent communication
Lesions in Brainstem, midbrain, hypothalamus result in disruption of what?
Consciousness
Which arousal systems are activated by EAA?
RAS
Parabrachial nuclei
Where do inputs to the RAS converge?
This convergence leads to loss of what?
On post-synaptic cell of RAS
Modal specificity
What are the 2 pathways of outputs from the RAS?
Dorsal
Ventral
The dorsal pathway travels via what nuclei?
Of what?
Where does the pathway end up?
Non-specific nuclei of the thalamus AND intra laminar nucleus of the thalamus
Diffuse pathway to all higher levels (nonspecific to the cortex)
The ventral pathway bypasses what?
Travels via what?
End result of the pathway?
Thalamus
Basal forebrain and hypothalamus
Diffuse pathway to higher levels (nonspecific to cortex)
Where are the Parabrachial nuclei located? what kind are there?
What pathway does it use to travel?
Pons -> medial, intermediate, and lateral
Ventral
What is the major nt used by both RAS neurons?
Glutamate
Within the RAS what is there a substantial # of? They release what?
What else is present there?
Interneurons that release GABA
Neurons that release Ach
Where is the RAS located?
Mid-ventral portion of medulla and midbrain
What are the associated nuclei of cholinergic arousal?
Pedunculopontine tegmental (PPT) and Lateraldorsal nuclei (LDT)
What happens w/cholinergic inputs?
Outputs?
Modality is lost
Use dorsal and ventral pathways
Activity in the cholinergic inputs from the pons is associated with what?
Damage to the PPT/DLT produces what?
Arousal and awareness
Severe cognitive deficits associated with generalized slowing of cortical processes
Where is the noradrenergic arousal system located?
Locus Ceruleus
Axons from the locus coereuleus travel to the cortex how?
What specifically?
Dorsal and ventral pathways
Dorsal noradrenergic bundle
What are the functions of the L.C. NA system?
Startle and alerting responses on EEG
Sleep-wake
Behavioral vigilance
Where is the serotonergic arousal system located?
Raphe nuclei
How do serotonergic outputs travel?
For arousal both the dorsal and ventral pathways
Fx of serotonergic system?
Quiet awareness
mood and affect
Modulation of pain
Where is the dopaminergic arousal system located?
Ventral tegmental area
The VTA along with what else provides dopaminergic input that is important to many functions?
What are the functions?
Substantia Nigra
Cognitive functions, motor activity, emotion
Thalamic arousal systems refer to what?
Dorsal pathway
Treatment with what drug while a patient is in the persistent vegetative state has produced dramatic increases in cognitive function?
Levodopa
Consciousness is recognized as having what 2 parts?
Arousal (being awake)
Awareness (conscious processing of inputs)
