Brain Arousal Systems

Question 1

what are the 2 parts of consciousness

Answer 1

1) arousal (being awake)

2) awareness (conscious processing of inputs, etc…)

Question 2

coma

Answer 2

neither awake or aware

Question 3

persistent vegetative state

Answer 3

physciologically identifiable wake/sleep cycles

no evidence of awareness

Question 4

minimally conscious stae

Answer 4

sleep/wake

reproducible evidence of awareness-ability to respond to simple commands

Question 5

disruptions of consciousness result from smaller lesions in ___ ____ or ____

Answer 5

upper brain stem
midrain (diencephalon)
midbrain and hypothalamus

Question 6

both arousal and awareness require activation of the ___

Answer 6

cortex

Question 7

arousal systems using the EAA

Answer 7

RAS

parabrachial nuclei

Question 8

where is the RAS

Answer 8

mid-ventral portion of medulla and midbrain

Question 9

inputs to RAS system from what

Answer 9

all ascending sensory tracts
visual
auditory
trigeminal

Question 10

ther is sufficient synaptic convergence of input to neurons of the RAS that what is lost

Answer 10

modal specificity

-brain knows something is happening, just not what has happened

Question 11

2 pathways of RAS

1) ___ and nucleus

Answer 11

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

Question 12

the outputs of parabrachial nuclei are likely exclusively via the ____ _____

Answer 12

ventral pathway

Question 13

within the RAS there is a substantial number of ____ that release ____
-RAS also has population that releases __

Answer 13

interneurons, GABA (regulation)

Ach

Question 14

EAA system provides what for cortical activity

Answer 14

baseline excitation that is cruscial for cortical activity

-get at least to point of sleep/wake cycles

Question 15

arousal system: PPT/LDT

Answer 15

similar to RAS in that receives all sorts of sensory info and has dorsal and ventral pathway
-major NT used is ACETYLCHOLINE

Question 16

role of PPT/LDT

Answer 16

baseline excitation of cortical activity

Question 17

what can damage to the PPN/LDT cause, how prevelant?

Answer 17

produce severe cognitive deficits associated with generalized slowing of cortical processes
-too specific, very rare

Question 18

noradrenergic input from what area

-vital for what?

Answer 18

locus ceruleus

awareness

Question 19

outputs from the locus ceruleus are both ___ and ____

Answer 19

ascending and descending

Question 20

ascending output from LC
(to cortex)
-specific name of one

Answer 20

dorsal and ventral with RAS

-ascending fibers from this group become the dorsal noradrenergic bundle

Question 21

the LC is ___ to the parabrachial nucleus

Answer 21

medial

Question 22

functions of the LC Noradrenergic system

Answer 22

startle and alerting (responses on EEG, reflects norep going up and activating cortical neurons)

sleep-wake

behavioral vigilance

Question 23

serotongeric nuclei?

outputs for what and what paths

Answer 23

raphe nuclei
arousal
both dorsal and ventral paths used

Question 24

serotongeric function

Answer 24

quiet awareness
mood and affect
modulation of pain

Question 25

dopaminergic nuclei and functions

Answer 25

Ventral tegmental area
input for:

cognitive functions
motor activity
emotion

Question 26

thalamic arousal systems, neurons with EAA input interact with ____ that release ___ to create oscillations on EEG

Answer 26

intracortical neurons that release GABA

• thalmacortical neurons
• level of control

Question 27

in persistent vegetative state rostral regions of pons/midbrain/thalamus show neuronal loss that exceeds that of cortex. Cortical neurons are ____-___ mV ____ relative to threshold

Answer 27

10-30 mV hyperpolarized

Question 28

in alzheimer’s disease which system is hard hit

Answer 28

cholinergic

Question 29

in limited number of people in persistent vegetative state, treatment with ___ has produced dramatic increase in cognitive function

Answer 29

levodopa

Question 30

during sleep the ____ neurons are hyperpolarized and show occasional bursts
what does this do

Answer 30

thalamocortical neurons

-cuts the cortex off from excitatory influence during deepestt levels of sleep