Arousal Flashcards

1
Q

Coma?

A

Neither awake nor alert

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2
Q

PVS?

A

Sleep/wake cycle present

No awareness

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3
Q

Minimally conscious state?

A

Sleep/wake present
Some awareness (to simple commands)
Limited/absent communication

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4
Q

What is the cause of most disruptions of consciousness?

A

Lesions of brainstem, midbrain and hypothalamus (not cortex)

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5
Q

What role does brainstem play in arousal?

A

It needs to “wake up” the cortex, since the cortex has no intrinsic mechanism for activation

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6
Q

List of arousal systems (in order of specificity)

A
EAA (RAS and PBN)
Cholinergic
Noradrenergic
Serotonergic 
Dopaminergic
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7
Q

RAS

A
  • @ midventral portion of medulla/midbrain
  • all ascending sensory tracts send info to RAS
  • descending tracts (trigeminal, auditory, visual) send info too
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8
Q

Loss of modal specificity?

A

RAS knows something is happening, but can’t determine where input is coming from

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9
Q

Dorsal pathway of RAS

A
  • Goes through nonspecific thalamic nuclei (intralaminar nucleus of thalamus)
  • Goes to higher brain centers from there
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10
Q

Ventral pathway of RAS

A
  • Bypasses thalamus, instead going through basal forebrain and hypothalamus
  • Goes to high brain centers after
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11
Q

Parabrachial Nuclei

A
  • Pons
  • Crucial for arousal/activation
  • Similar sensory inputs as RAS
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12
Q

What pathway do PBN exclusively use?

A

Ventral

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13
Q

What NTs do RAS and PBN use?

A

EAA (glutamate)

RAS also releases Ach and GABA (via interneurons)

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14
Q

Overall purpose of EAA system in arousal?

A

Provides a baseline level of excitement crucial to cortical activity

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15
Q

Location of cholinergic system?

A

Pedunculopontine tegemental (PPT) and laterodorsal nuclei (LDT)

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16
Q

Output pathways of PPT/LDT?

A

Dorsal and Ventral

17
Q

What level of specificity do PPT and LDT nuclei transmit?

A

Very basic (the modality-specific info is lost)

18
Q

Purpose of cholinergic system?

A
Baseline excitation (and arousal/awareness)
- Damage to PPT and LDT -- severe cognitive deficits (slowing of cortical processes) {Alzheimer's}
19
Q

Location of Noradrenergic system?

A

Locus Ceruleuns

20
Q

Inputs to Noradrenergic system?

A
  • Paragigantocellularis (rostral medulla) for sensory info
  • Periaqueductal grey
  • Higher centers (cortex)
21
Q

Outputs of noradrenergic system?

A
  • Ascending (dorsal and ventral)

- Descending (dorsal adrenergic bundle)

22
Q

Functions of noradrenergic system?

A
  • Startling and alerting

- Behavior vigilance

23
Q

Serotonergic nuclei location?

A

Midline raphe nuclei

24
Q

Inputs to serotonergic system?

A

From spinal cord (proprioception, trigeminal, PAG)

25
Q

Output of serotonergic system?

A

Dorsal and Ventral

26
Q

Serotonergic system functions?

A
  • Quiet awareness
  • Mood/affect
  • Modulation of pain
27
Q

Dopaminergic system location?

A

Ventral tegmental area (and substantia nigra)

28
Q

Function of dopaminergic system?

A
  • Cognitive functions
  • Motor activity
  • Emotion
29
Q

Outputs of dopaminergic system?

A

Dorsal and Ventral

30
Q

Alzheimer’s disease

A
  • Cholinergic system is hit hard

- Mental processes slowed and memory formation impaired

31
Q

PVS and EAA?

A
  • Rostral regions of brainstem show neuronal loss > that of cortex
  • Cortical neurons are 10-30 mV hyperpolarized vs. threshold
32
Q

What is the purpose of the alerting response from NE?

A

Early indicator that the cortex is expecting a sensory input

33
Q

What is happening with thalamocortical neurons during sleep?

A

They are hyperpolarized and have occasional bursts of activity
- Cortex is cut off from excitatory influence during sleep