brain arousal Flashcards

1
Q

what are the two characteristics of persistent vegetative state

A

sleep/wake cycles

no evidence of awareness

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2
Q

what are the characteristics of a minimally conscious state

A

sleep/wake cycles
ability to respond to simple commands
limited/absent communication

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3
Q

what kind of injury most commonly causes disruption of conciousness

A

small lesions to the brainstem, midbrain or hypothalamus

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4
Q

will a patient in a coma or persistent vegetative state has eye/head motions?

A

YES, reflexes

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5
Q

what system releases excitatory amino acids?

A

reticular activating system

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6
Q

how does the dorsal pathway of the reticular activating system excite the cortex

A

via nuclei of the thalamus (INTRALAMINAR NUCLEUS OF THE THALAMUS) => diffuse pathway to higher levels

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7
Q

how does the ventral pathway of the reticular activating system excite the cortex

A

via basal forebrain and hypothalamus

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8
Q

what do the parabrachial nuclei do and why

A

release EAAs for arousal

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9
Q

do the parabrachial nuclei excite the cortex via the dorsal or ventral pathway?

A

ventral pathway only

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10
Q

do the peduncopontine tegmental and laterodorsal (PPT/LDT) nuclei excite the cortex via the dorsal or ventral pathway?

A

BOTH

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11
Q

what is the major NT of the PPT/LDT nuclei

A

ACh

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12
Q

does damage to the PPT/LDT nuclei cause coma

A

no, it causes severe cognitive deficits and slowing of cortical processes

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13
Q

how would a patient with RAS, PPT/LDT and parabrachial nuclei functioning be characterized

A

persistent vegetative state (awake, but not alert or aware)

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14
Q

what are the two inputs to the locus coereulus?

A

paragigantocellularis n

periaqueductal grey

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15
Q

what do the ascending fibers from the locus coereulus become?

A

the dorsal noradrenergic bundle

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16
Q

does the locus coereulus excite the cortex via the dorsal or ventral pathway?

17
Q

what is the main function of the locus coereulus system

A

startling and alerting- pt aware of specific event

18
Q

what is the source of serotonergic input to the cortex?

A

raphe nuclei

19
Q

what is the source of noradrenergic input to the cortex?

A

locus coereulus

20
Q

what is the source of cholinergic input to the cortex?

A

PPT/LDT nuclei

21
Q

what is the function of serotonergic activation of the cortex?

A

quiet awareness

22
Q

what structure facilitates quiet awareness?

A

raphe nuclei

23
Q

does the raphe nuclei excite the cortex via the dorsal or ventral pathway?

24
Q

if the noradrenergic and serotonergic pathways are functioning in a patient, how are they characterized?

A

awake and aware, NOT alert

25
what kind of input facilitates alertness
dopaminergic
26
what structure provides dopaminergic input to the cortex
ventral tegmental area (VTA)
27
what input to the cortex facilitates cognitive function, motor activity and emotion
dopaminergic
28
what is the route of axons on the dorsal pathway to the cortex
arousal center => thalamus (synapse) => cortex
29
what is the route of axons on the ventral pathway to the cortex
arousal center => cortex => synapse on cortical neurons
30
what creates the oscillations on EEG
intracortical neurons which interact with thalamic projections and release GABA
31
in a persistent vegetative state, are cortical neurons hypo- or hyper polarized?
hyperpolarized 10-20 mV
32
what causes memory impairment and slowing of mental processes in alzheimer's dz
destruction to cholinergic systems
33
during REM sleep, what physiologic changes cuts the cortex off from excitation?
hyperpolarization of the thalamocortical neurons