Mechanisms of Arousal: Brain Arousal Systems

Question 1

What are the two parts of consciousness

Answer 1

arousal and awareness

Question 2

Coma

Answer 2

neither awake nor aware

Question 3

persistent vegetative state

Answer 3

physiologically identificable sleep/wake cycles, no awareness

Question 4

minimally conscious state

Answer 4

sleep/wake cycles, reproducible evidence of awareness, limited/absent communication

Question 5

Comatose state results from damage to the cerebral cortex in what circumstance

Answer 5

damage must be large and bilateral

Question 6

What is a common cause of consciousness

Answer 6

smaller lesion in brainstem, mid brain or hypothalamus

Question 7

What is required for both arousal and awareness

Answer 7

activation of the cortex

Question 8

what is present in a coma

Answer 8

eye/head motions, that are intermittent

Question 9

what is present in a persistent vegetative state

Answer 9

eye/head movements, sleep/wake cycles

Question 10

What is present in minimally conscious individual

Answer 10

eye/head motions; sleep/wake cycle; awareness and verbal responses are intermittent

Question 11

aware/alert individual has

Answer 11

eye/head motions; sleep/wake cycles; awareness and verbal responses

Question 12

What are the arousal systems/compounds

Answer 12

EAA
cholinergic
noradrenergic
serotonergic
dopaminergic

Question 13

Where are EAA arousal systems located

Answer 13

reticular activating system and parabrachial nuclei

Question 14

Where are cholinergic arousal systems located

Answer 14

pedunculopontine tegmental and laterodorsal nuclei (PPT/LDT)

Question 15

Where are noradrenergic arousal system located

Answer 15

locus ceruleus

Question 16

Where are serotonergic arousal systems located

Answer 16

raphe nuclei

Question 17

where are dopaminergic arousal systems located

Answer 17

ventral tegmental area

Question 18

What are the two pathways of the RAS pathway

Answer 18

Dorsal and ventral

Question 19

What is the path of the dorsal pathway

Answer 19

nonspecific nuclei of thalamus, including intralaminar nucleus. Goes from there to diffuse pathway to higher levels.

Question 20

What is the path of the ventral pathway

Answer 20

Basal forebrain and hypothalamus, diffuse pathway to all higher levels after that.

Question 21

Where are the parabrachial nuclei located

Answer 21

In the pons

Question 22

Function of parabrachial nuclei

Answer 22

crucial for arousal/activation

Question 23

What is the path the parachial nuclei take

Answer 23

Exclusively ventral pathway with extensive diffuse innervation of the entire cortex

Question 24

What are the neurotransmitters used by both parabrachial and RAS neurons

Answer 24

EAA/Glu (dorsal and ventral pathways)

Question 25

What other products are released by interneurons and neuronal population in the RAS?

Answer 25

Interneurons=GABA | Neuronal population= ACh

Question 26

What does EAA system provide

Answer 26

Baseline excitation crucial for cortical activity

Question 27

What path does PPT/LDT take

Answer 27

both dorsal and ventral

Question 28

What does cholinergic system provide for cortical activity

Answer 28

baseline excitation crucial to cortical activity

Question 29

What is cholinergic inputs from pons associated with

Answer 29

arousal and awareness

Question 30

Does PPN/DLT cause coma

Answer 30

not necessarily, does cause severe cognitive deficits from slowing cortical processes

Question 31

What neurotransmitters lead to arousal/wakefulness

Answer 31

EAA/Ach

Question 32

What are the outputs from teh Locus coereuleus

Answer 32

ascending and descending

Question 33

What pathways does the ascending output of the locus coereuleus follow

Answer 33

dorsal and ventral with RAS

Question 34

What do the ascending fibers in the L.C. become

Answer 34

dorsal noradrenergic bundle

Question 35

Function of LC. NA system

Answer 35

startle and alerting responses on EEG sleep/wake behavioral vigilance

Question 36

What are the inputs of the raphe nuclei

Answer 36

sensory from SC (fine proprioception, trigeminal and PAG)

Question 37

What are the outputs for arousal of the raphe nuclei

Answer 37

dorsal and ventral paths

Question 38

Function of serotonergic

Answer 38

quiet awareness, mood and affect, modulation of pain

Question 39

What neurotransmitters lead to awareness

Answer 39

NE/5HT

Question 40

What provides a dopaminergic input

Answer 40

VTA along with substantia nigra

Question 41

Functions of VTA

Answer 41

cognitive functions, motor activity, emotion

Question 42

What neurotransmitters lead to alertness

Answer 42

DA

Question 43

What is the pathway for the dorsal pathway

Answer 43

arousal systems send axons to thalamus, then synapse and axons from thalamus then go to cortex. Synapse on cortical neurons.

Question 44

Where does the dorsal pathway neurons synapse

Answer 44

non-specific nuclei of the thalamus. Difuse projection to the entire cortex, use EAA as neurotransmitter

Question 45

What do the Thalamic arousal system neurons interact with

Answer 45

with EAA and neurons, interact with a series of intracortical neurons release GABA.

Question 46

What parts of the brain show neuron loss in a persistent vegetative state

Answer 46

rostral regions of pons, midbrain, thalamus

Question 47

In Alzheimer's disease, what is hurt?

Answer 47

cholinergic systems, memory formation is profoundly impaired.

Question 48

What systems move us from being awake to more generally aware

Answer 48

noradrenergic and serotonergic

Question 49

What medicine has helped people in a persistent vegetative state

Answer 49

levodopa

Question 50

What does dopaminergic system do

Answer 50

adds to awareness, focused on novel stimuli

Question 51

What happens during sleep in the thalamic arousal system?

Answer 51

thalamocortical neurons are hyperpolarized, show occasional burst, cuts cortex off from excitatory influence during the deepest levels of sleep