Brain Arousal Systems Flashcards
what are the 2 parts of consciousness
1) arousal (being awake)
2) awareness (conscious processing of inputs, etc…)
coma
neither awake or aware
persistent vegetative state
physciologically identifiable wake/sleep cycles
no evidence of awareness
minimally conscious stae
sleep/wake
reproducible evidence of awareness-ability to respond to simple commands
disruptions of consciousness result from smaller lesions in ___ ____ or ____
upper brain stem
midrain (diencephalon)
midbrain and hypothalamus
both arousal and awareness require activation of the ___
cortex
arousal systems using the EAA
RAS
parabrachial nuclei
where is the RAS
mid-ventral portion of medulla and midbrain
inputs to RAS system from what
all ascending sensory tracts
visual
auditory
trigeminal
ther is sufficient synaptic convergence of input to neurons of the RAS that what is lost
modal specificity
-brain knows something is happening, just not what has happened
2 pathways of RAS
1) ___ and nucleus
1) dorsal pathway
- neurons synapse on non specific nuclei of thalamus including intralaminar nucleus of the thalamus
from there they diffuse to cortex
2) ventral via basal forebrain and hypothalamus
- bypass thalamus and go to cortical neurons
the outputs of parabrachial nuclei are likely exclusively via the ____ _____
ventral pathway
within the RAS there is a substantial number of ____ that release ____
-RAS also has population that releases __
interneurons, GABA (regulation)
Ach
EAA system provides what for cortical activity
baseline excitation that is cruscial for cortical activity
-get at least to point of sleep/wake cycles
arousal system: PPT/LDT
similar to RAS in that receives all sorts of sensory info and has dorsal and ventral pathway
-major NT used is ACETYLCHOLINE
role of PPT/LDT
baseline excitation of cortical activity
what can damage to the PPN/LDT cause, how prevelant?
produce severe cognitive deficits associated with generalized slowing of cortical processes
-too specific, very rare
noradrenergic input from what area
-vital for what?
locus ceruleus
awareness
outputs from the locus ceruleus are both ___ and ____
ascending and descending
ascending output from LC
(to cortex)
-specific name of one
dorsal and ventral with RAS
-ascending fibers from this group become the dorsal noradrenergic bundle
the LC is ___ to the parabrachial nucleus
medial
functions of the LC Noradrenergic system
startle and alerting (responses on EEG, reflects norep going up and activating cortical neurons)
sleep-wake
behavioral vigilance
serotongeric nuclei?
outputs for what and what paths
raphe nuclei
arousal
both dorsal and ventral paths used
serotongeric function
quiet awareness
mood and affect
modulation of pain
