Mechanisms of Arousal Flashcards
arousal =
being awake
Consciousness is recognized by having two parts
- arousal
2. awareness
awareness=
conscious processing of inputs
Coma
neither awake (arousal absent) nor aware
Persistent vegetative state
physiologically identifiable sleep/wake cycles appear (arousal)
no evidence of awareness
minimally conscious state
sleep wake cycles (arousal)
reproducible evidence of awareness - ability to respond to simple commands
limited or absent communication
Misconception with comatose state
primarily from damage to cerebral corticies
(this can be true, but damage must be massive)
Led to the hypothesis that BRAINSTEM regions are critical for arousing the cortex
Both arousal and awareness require the activation of the _____
what is the caveat to this
how do we resolve it
cortex
the cortex has no intrinsic mechanism for activation
there are multiple subcortical structures that function to provide the activation required for the cortex to function
What are the 5 types of arousal systems
EAA cholinergic noradrenergic seratonergic dopaminergic
What are the EAA activating regions
Reticular activating system (RAS)
parabrachial nuclei
What are the Cholinergic activating regions of the brain
pedunculopontine tegmental and laterodorsal nuclei
PPT and LDT
What is the Noradrenergic activating region of the brain
locus ceruleus
what is the seratonergic activating region
raphe nuclei
What is the dopaminergic activating region
ventral tegmental area
EAA: inputs to the RAAS
all ascending sensory tracts send information to the RAS, as well as
trigeminal
auditory
visual
EAA: inputs to the RAS
describe how the RAS responds to multiple sensory modalities
there is sufficient synaptic convergence of input to the neurons of the RAS that MODAL SPECIFICITY IS LOST.
the neurons of the RAS respond equally well to multiple sensory modalities.
EAA: Outputs from the RAS - waht are the two pathways
- dorsal pathway
2. ventral pathway