Mechanisms of Arousal Flashcards
arousal
being awake
awareness
conscious processing of inputs
coma
neither awake or aware
persistent vegetative state
identifiable sleep/wake cycles appear
no evidence of awareness
minimally conscious state
sleep/wake cycles
reproducible evidence of awareness - ability to respond to simple commands
limited or absent communication
Reticular activating system (RAS)
mid ventral medulla and midbrain
all ascending sensory tracts send info
all sensory info converges on the same neurons so the brain only knows something happened, not what happened
outputs are via dorsal and ventral pathways
dorsal pathway
non specific nuclei of the thalamus and intralaminar nucleus of the thalamus then will send neurons to the whole cortex
ventral pathway
basal forbrain and hypothalamus send neurons to the whole cortex
bypass the thalamus
parabrachial nuclei
pons
crucial for arousal/activation
sensory input from the whole body comes in
outputs are via ventral pathway
RAS and Parabrachial nuclei
major NT - EEA/ glutamate
allows the cortical neurons to get close enough to threshold, but not normal yet
Cholinergic PPT/LDT
input is all sensory information
output is via ventral and dorsal pathways
NT is Ach
provides a baseline excitation that is crucial to cortical activity
noradrenergic Locus ceruleus
inputs not well understood
outputs ascending via the dorsal and ventral pathways
functions: startle and alerting responses on EEG, sleep-wake, behavioral vigilance
NT - NE
seotonergic raphe nuclei
inputs - multiple
outputs - arousal is both dorsal and ventral pathways
functions - quite awareness, mod and affect, modulation of pain
NT - 5HT
dopaminergic ventral tegmental area
functions - cognitive function, motor activity, emotion
RAS/Parabrachial EAA systems
crucial for increasing general excitability of cortical neurons
AROUSAL/WAKEFULNESS
