Neuro Ch. 14 unfinished Flashcards
1
Q
What is the reticular formation?
A
a central core of nuclei that runs the entire length of the brainstem
2
Q
What is the reticular formation continuous with rostrally?
A
diencephalic nuclei
3
Q
what is the reticular formation continuous with caudally?
A
intermediate zone of the spinal cord
4
Q
Where is the rostral reticular formation located?
A
mesencephalon and upper pons
5
Q
What is the function of the rostral reticular formation?
A
maintain alert, conscious state in the forebrain
6
Q
Where is the caudal reticular formation located?
A
pons and medulla
7
Q
What is the function of the caudal reticular formation?
A
work with CN and spinal cord to carry out motor, reflex, and autonomic functions
8
Q
Where is the reticular formation located?
A
in the brainstem tegmentntum, running the entire length of the brainstem
9
Q
What is the function of the periaqueductal gray matter?
A
pain modulation
10
Q
What area of the CNS is involved with nausea?
A
chemotacti trigger zone (area postremea) in the medulla
11
Q
What areas of the CNS forms the consciousness system?
A
principally the medial and lateral frontoparietal association cortex, with arousal circuits in the upper brainstem and diencephalon
12
Q
How is consciousness divided?
A
content of consciouness (systems mediating sensory, motor, memory, and emotional fnxs), and the level of consciousness (regulated by the consciousness system)
13
Q
What three process are involved in the control of the level of consciousness?
A
alertness, attention, and awareness
14
Q
Alertness depends on normal function of what areas of the CNS?
A
brainstem and diencaphalic arousal circuits and the cortex
15
Q
What areas are involved with attention?
A
brainstem, diencaphlic arousal circuits, cortex, and additional processin in frontoparietal association cortex
16
Q
In general, where in the brain can a lesion cause coma?
A
upper brainstem reticular formation and related structures, or widespread/extensive bilateral regions of the cortex
17
Q
What are diffuse/widespread projections systems?
A
emenate from a single region to innervate many structures or even the entire nervous system
18
Q
Where do projections that innervate the forebrain arise from?
A
the upper brainstem (midbrain to rostral pons)
19
Q
Where do projectections to the brainstem, cerebellum, or spinal ord arise from?
A
lower pons or medulla
20
Q
Where are the widespread projection systems that arise outside the brainstem?
A
hypothalamus (histamine) or basal forebrain (acetylcholine)
21
Q
What are the two main functions of neurotransmitters?
A
- mediate communication b/w neurons through fast excitatory or inhibitory postsynaptic potentials
- Neuromodulation (slower)
22
Q
What is neuromodulation?
A
a broad range of cellular mechanisms involveing signaling cascades that regulate synaptic transmission, neuronal growth, and other functions; either facilitates or inhibits the subsequent signaling properties of the neuron
23
Q
What is the main excitatory neurotransmitter in the CNS?
A
glutamate
24
Q
What is the main inhibitory neurotransmitter in the CNS?
A
gamma-aminobutyric acid (GABA)
25
What is the main function of the neurotransmitters in the diffuse projection systems?
neuromodulation
26
Do lesions or pharmacological blockades of the individual projecting neurotransmitter systems result in coma?
no, but they can result in profound confusion or drowsiness (esp. ACh and histamine)
27
Where are the cell bodies of the reticular formation projection system?
Midbrain and rostral pons
28
What are the main targets of the reticular formation projection system?
thalamic intralaminar nuclei, hypothalamus, basal forebrain
29
What are neurotransitters are involved in the reticular formation projection system?
unknown, although many neurons contain glutamate
30
What are the functions of the reticular formation projection system?
maintaining normal alterness
31
Where are the intralaminar nuclei projection system cell bodies?
thalamic intralaminar nuclei (particularly rostral)
32
What are the main targets of the intralaminar nuclei projection system?
cortex, striatum, (also has reciprocal connections with the basal ganglia)
33
What neurotransmitters are involved with the intralaminar nuclei projection system?
unknown, although many neurons contain glutamate
34
What is the function of the intralaminar nuclei projection system?
maintaining normal alterness
35
Where are the cells bodies of the midline thalamic nuclei projection system?
midline thalamic nuclei
36
What are the main targets of the midline thalamic nuclei?
cortex
37
What is the neurotransmitter involved with midline thalamic nuclei projection system?
unknown, although many neurons contain glutamate
38
What is the function of the midline thalamic nuclei projection system?
maintaining normal alterness
39
What is te major efferent neurotransmitter of the PNS?
Acetylcholine
40
Where is acetylcholine found in the PNS
neuromuscular junction, preganglionic autonomic synapses, and postganglionic parasympathetic synapses
41
What are the two main locations of neuromodulatory cholinergic neurons?
pontomesencephalic region of the BS, and basal forebrain
42
Where are the cholinergic neurons of the pontomesencephalic brainstem found?
pedunculopontine tegmental nuclei, and the laterodorsal tegmental nuclei
43
Where are the cholinergic neurons of the basal forebrain found?
nucleus basalis, medial septal nucleus, and nucleus of diagonal band (of Broca)
44
What cholinergic nuclei project to the hippocampus?
medial spetal nucleus, and nucleus of diagonal band (of Broca)
45
Stimulation of what region causes coordinated locomotor movement?
pedunculopontine tegmental nuclei, sometimes calles mesencephalic locomotor region, which has a role in motor systems
46
Where do cholinergic inputs to the cortex arise from?
basal forebrain - nucleus basalis to entire cerebral cortex
47
What is the hippocampal theta rhythm? What nuclei are involved?
a rhythmic oscillation that plays a role in memory function; from medial septal nuclei and nucleus of the diagonal band (of Broca) in basal forebrain
48
Where are more short-range chlinergic interneurons found?
striatum, and some in cerebral cortex, and cerebral habenula to interpeduncular nucleus
49
What are the cholinergic receptor types in the CNS?
muscarinic (M1-5) is the main one, also nicotinic
50
What are the main functions of acetylcholine in the CNS?
facilitation of attention, memory, and learning
51
What is the effect of pharmacological blockade of central cholinergic transmission?
delirium and memory deficits
52
Degeneration of cholinergic neurons in what region is involved in memory decline seen in Alzheimer's disease?
basal forebrain - nucleus basalis to entire cerebral cortex
53
What is the effect of cholinergic blockade on striatal neurons?
movement disorders
54
Where are dopaminergic neurons with more localized functions found?
retina, olfactory bulb, hypothalamus (inhibiting prolactin release), and medulla
55
What are the three dompaminergic projection systems?
mesostriatal (nigrostriatal), mesolimbic, and mesocortical
56
Where are dopaminergic neurons of the CNS located?
ventral midbrain: substantia nigra pars compacta (mesostriatal and ome mesocortical neurons), and ventral tegmental area (mesolimbic and mesocortical)
57
Where do dopaminergic neurons of the CNS project?
mesostriatal/nigrostriatal: putamen and caudate of the striatum
mesolimbic: amygdala, limbic cortex (medial orbital cortex, cingulate cortex, nucleus accumbens, hippocampus and parahippocampa gyrus)
mesocortical: prefrontal cortex
58
What receptors are involved with CNS dopaminergic neurons?
D1-5
59
What are the functions of dopaminergic projection pathways?
mesostriatal/nigrostriatal: movement
mesolimbic: role in reward circuitry and addiction
mesocortical: working memory and attentional aspects of motor initiation
60
What are the effects of dysfunctions of the dopaminergic pathways?
mesostriatal/nigrostriatal: movement disorders like PD - treat with agonists
mesolimbic: overactivity leads to "positive" sx of schizo (hallucinations) - treat with antagonist
mesocortical: cognitive deficits and hypokinesia involved in PD, "negative" sx of schizo
61
Where are noradrenergic neurons found?
locus ceruleus (near 4th ventrical in rostral pons) and lateral tegmental area (pons and medulla)
62
Where do ascending noradrenergic neurons project?
from pons to entire forebrain
63
Where do noraderenergic neurons of of the caudal pons and medulla project?
cerebellum, brainstem, and spinal cord
64
Where do noraderenergic neurons project?
entire CNS (entire forebrain, cerebellum, brainstem, and spinal cord)
65
What effects does norepinephrine exhibit on the cortex?
can be inhibitory or excitatory
66
What effects does norepinephrine exhibit on the thalamus?
generally excititatory
67
What are the functions of the norepinephrine/noradrenaline projection system?
alertness, mood elevation, and sleep-wake states, also involved in pain modulation with serotonin
68
what neurotransmitter receptors are involved with norepinephrine in the CNS?
alpha1A-D, alpha2A-d, and beta1-3
69
What is seen in neuron firing in the locus ceruleus in sleep-wake states?
Firing increases in the awake state and decreases in the sleep state
70
What diseases are associated with noradrenergic dysfunction?
ADD - treated with noradrenergic-enhancing medications
narcolepsy - treated with noradrenergic-enhancinc medications
mood disorders (with serotonin): depression, bipolar, anxiety disorders, OCD
also involved in pain modulation with serotonin
71
Where are neurons containing serotonin found?
raphe nuclei of midbrain, pons, and medulla (in midline of brainstem), small amounts in spinal cord and other brainstem regions (area postrema, caudal locus ceruleus, around the interpeduncular nucleus)
72
What are the midbrain raphe nuclei?
nucleus linearis, dorsal raphe nucleus, and medial raphe nucleus
73
What are the raphe nuclei of the pons?
nucleus raphe pontis, and nucleus raphe magnus
74
What are the raphe nuclei of the medulla?
nucleus raphe pallidus, nucleus raphe obscuris
75
What are the rostral raphe nuclei?
raphe nuclei of midbrain and rostral pons
76
What are the caudal raphe nuclei?
raphe nuclei of caudal pons and medulla
77
To where does the serotonin projection system project?
Entire CNS
rostral raphe nuclei: entire forbrain (cortex, thalamus, and basal ganglia)
caudal raphe nuclei: cerebellum, medulla, and spinal cord
78
What are the function of the serotonin projection system?
alertness, mood elevation, and breathing control
| caudal raphe nuclei to spine and medulla: pain modulation, breathing, and temperature control
79
What clinical syndromes are associated with serotonergic pathways?
several psychiatric syndromes (depression, anxiety, OCD, aggression, certain eating disorders); SIDS (impaired arousal in response to hypoventilation)
80
What regions/neurons exhibit decreased neuron firing during sleep states?
locus ceruleus (noradrenergic) and serotonergic neurons (raphe nuclei of midbrain, pons, and medulla?, or maybe those found in the caudal locus ceruleus? I speculate here)
81
What neurotransmitter receptors are involved with serotonergic projections pathways?
5-HT1A-F, 5-HT2A-C, 5-HT3-7
82
Is serotonin exhitiatory or inhibitory in the CNS?
both, sometimes even within the same structure
83
Where are the cell bodies of the histamine projection system found?
mainly in the tuberomamillary nucleus (posterior hypothalamus), also the reticular formation of the mibrain)
84
Where do histamine neurons project?
entire brain? (forebrain? CNS? Idk what they mean by "brain" see fig. 14.13)
85
What receptors are involved with the histamine projection system?
H1-3
86
What are the functions of histamine in the CNS?
maintaining alertness
87
What are the functions of histamine in the PNS?
immune responses and allergic reactions
88
Where is the majority of histamine found in the body?
outside the nervous system in mast cells
89
What is the effect of histamine on thalamic neurons?
excitatory effects
90
What is the effect of histamine on cortical neurons
both excitatory and inhibitory
91
What is the side-effect of antihistamines used to treat allergies?
causes drowsiness by blocking CNS histamine receptors
92
What is orexin?
a peptide neurotransmitter; aka hypocretin
93
Where are orexinergic neurons found?
posterior lateral hypothalamus
94
What are the targets of orexin?
entire brain (cortex and brainstem)
95
What are the receptors for orexin in the CNS?
OX1, and OX2
96
What are the functions of orexin?
alertness, and food intake
97
What is adenosine and its functions?
a neurotransmitter that may be important in mechanisms of alertness, concentrations vary in a circadian manner (promoting sleep?)
98
Where are adenosine receptors found in the CNS?
thalamus and cortex
99
What is the effect of adenosine in the CNS?
inhibitory
100
When do adenosine concentrations reach their maximum?
just before sleep begins
101
What is a possible mechanism of caffeine?
produce alertness by blocking adenosine receptors
102
What are the roles of GABA?
main inhibitory neurotransmitter in the CNS; inhibits local interneurons
and long-range inhibitory projections as well
- basal forebrain projecting to widespread cortical areas
- reticular nucleus of thalamas to other thalamic nuclei and to rostral brainstem reticular formation: gate info flow and regulates oscillatory electrophysiological activity underlying sleep and arousal
- hypothalmic neurons (ventrolateral preoptic area): promote sleep by inhibiting serotonergic, noradrenergic, histaminergic, and cholinergic arousal systems
103
How does GABA promote sleep?
GABAergic neurons int eh VPLO (vetrolateral peroptic area) inhibit?
- histaminergic and orexinergic neurons in the posterior hypothalamus
- and serotonergic, noraderenergic, dopaminergic, and cholineric arousal systems in the brainstem
104
What is galanin?
a peptide neurotransmitter that contributes to the inhibitory pathway with GABA promoting nonREM sleep
105
How many stages of sleep are there?
5 stages
106
What are the stages of nonREM sleep
stages 1-4
107
What stage is REM sleep?
stage 5
108
Why is REM sleep also called paradoxical sleep?
because in some ways REM is a deeper stage of sleep than stage 4, and in other ways it more closely resembles the awake state
109
In what way is REM sleep resemble a deeper sleep?
general muscle tone and brainstem monoaminergic neurotransmission are lower
110
In what way does stages 3 and 4 appear deeper than REM sleep?
EEG of REM resembles awake activity (low-voltage mixture of relatively fast activity), while EEG of stages 3-4 resemble coma (high-voltage slow activity), and it's easier to wake someone from REM
111
Transection experimnets in cats at what level produced coma?
Midbrain and rostral pons
112
What was the significance of transection experiments producing coma?
demonstrated the importance of the reticular formation in maintaining the awake state
113
Transection of what level in cats reduced sleep?
lower pons
114
What was the significance of transection experiments that reduced sleep?
suggested the presence of sleep-promoting regions in the medula (postulated to be in the medullary reticular formation and nucleus solitarius)
115
Lesions in what regions can markedly reduce sleep?
certain regions of the medulla, anterior hypothalamus, and basal forebrain
116
What is the role of the VLPO in the sleep-wake cycle?
promotes nonREM sleep by inhibiting ascending activating systems that project to the forebrain, also inhibits orexin secretion from the posterior lateral hypothalamus (through release of GABA and galanin)
117
What is the role of the posterior lateral hypothalamus in the sleep-wake cycle?
neurons that produce the peptide orexins/hypocretins, which excite the brainstem and hypothalamic arousal systems
118
What is encephalitis lethargica?
an epidemic during WWI in which patient slept for long periods due to damage in the posterior hypothalamus (which we now know is the site of orexenergic neurons)
119
Where are REM-on cells located?
pontine reticular formation (GABAergic and glutamatergic REM-on cells)
120
What is the mechanism behind REM sleep?
1. GABAergic REM-on cells and VLPO inhibit monaminergic transmission (NE and 5-HT) and orexin neurons
2. removal of inhibtion from cholinergic neurons
3. increased cholinergic transmission to thalamus results in EEG resembling wake state
4. brainstem cholinergics produce PGO waves, which induce dreams and REM
5. brainstem cholinergics activate glutamatergic REM-on cells, which activate glycine circuits in medulla and spinal cord, resulting in decreased muscle tone
121
What happen to NE and 5-HT neurons during the stages of sleep?
progressively reduced firing through stages 1-4; virtually silent in stage 5
122
What causes the EEG appearance of activity resembling the waking state during REM sleep?
inhibition of the monaminergic neurons (NE and 5-HT) leads to removal of inhibition from cholinergic neurons, resulting in increased cholinergic transmission to the thalamus
123
What are PGO waves?
pnto-geniculo-occiptal waves, waves of activation from brainstem cholinergics passing from pons-to-thalamus-to-cortex, thought to produce the visual imagery of dreams and REM
124
What are glutamatergic REM-on cells?
a class of REM-on cells in the pontine reticular formation, that activate inhibitory glycine circuits in the medulla and spinal cord, which inhibits tonic muscle activity and decreases muscle tone
125
What is the effect of glycine on the medulla and spinal cord?
inhibitory, which inhibits lower motor neurons and cases decreased muscle tone during REM sleep (activated by glutamatergic REM-on cells)
126
What is REM sleep behavioral isorder?
loss of normal inhibition of motor activity during REM sleep, resulting in complex activities during dreaming; sometimes seen as a precursor of parkinsonism
127
How can transitions from sleep and wake, and REM and nonREM be decsrcibed?
as a flip-flop switch; two systems that inhibit each other and therefore switch strongly from one on and the other off to the opposite state
128
What is melanin?
a hormone whose neurons are located near orexin neurons; most active in REM sleep, least active in waking state
129
What is the role of the suprachiasmatic nucleus of the hypothalamus?
sets the circadian rhythms and synchronizes them with the light-dark cycle through inputs from the retina
130
What is narcolepsy?
abnormal tendency to eaily enter REM sleep directly from the waking state
131
What neurons are involved with nacrolepsy?
oxrexinergic neurons
132
what are the four classic clinical findings of narcolepsy?
excessive daytime sleepiness, cataplexy, hypnagogic or hypnopompic dreamlike hallucinations, sleep paralysis
133
what is cataplexy?
sudden loss of muscle tone from the awake state, often in response to an emotional stimulus
