Mayo Clinic Iv - 28 - Sleep Pathophysiology

Front 1

A normal night of adult sleep typically consists of how many cycles of REM and NREM sleep?

Back 1

Between 4 and 6 cycles, each lasting approximately 90 minutes

Front 2

N1 sleep is characterized by?

Back 2

1. Shift from alpha rhythm (8-13 Hz) to theta activity (4-7 Hz)

2. Vertex (V) waves with a duration of less than 0.5 s and maximal expression over the central head regions

3. Slow roving horizontal eye movements

Front 3

N2 sleep is defined by what EEG phenomena?

Back 3

1. K complexes

2. Sleep spindles

Front 4

What are K complexes?

Back 4

Waveforms with a well-delineated negative sharp wave immediately followed by a positive component with a duration of 0.5 seconds or longer, usually maximal when recorded over frontal derivations

Front 5

What are sleep spindles?

Back 5

Train of distinct waves with a frequency of 11 to 16 Hz (most commonly 12-14 Hz) and a duration of 0.5 s or longer

Front 6

Stage N3 sleep is characterized by?

Back 6

High-amplitude synchronized EEG activity with a frequency of 0.5 to 2.0 Hz

Front 7

REM sleep is characterized by?

Back 7

Asynchronous, low-amplitude, mixed-frequency EEG activity; rapid eye movements

Front 8

What are sawtooth waves?

Back 8

The only named waveform of REM sleep; a train of sharply contoured or triangular, often serrated 2- to 6-Hz waves

Front 9

Function of N3 sleep?

Back 9

Restorative and reparative state and plays an important role in numerous physiologic processes, including cognition, endocrine function and neuroimmunologic signaling

Front 10

What is the function of REM sleep?

Back 10

Remains unclear but probably include consolidation of procedural and spatial memory

Front 11

When are all named sleep-related waveforms generally present?

Back 11

By about 6 months

Front 12

Difference between sleep phases in neonates and adults?

Back 12

NREM and REM are referred to as quiet and active sleep respectively, and in the first few months of life, active sleep comprses approximately half of total sleep time, while the proportion of REM sleep declines and latency to the first REM period increases

Front 13

EEG of NREM sleep has their maximal expression over which regions during the different stages of NREM sleep?

Back 13

N1 - Central

N2 - Central

N3 - Frontal

Front 14

Affected neurons in a wake state

Back 14

All active

Front 15

Affected neurons in NREM sleep

Back 15

Cholinergic - Silent

Noradrenergic - Partially active

Serotonergic - Partially active

Hypocretinergic - Silent

Front 16

Affected neurons in REM sleep

Back 16

Cholinergic - Active

Noradrenergic - Silent

Sertonergic - Silent

Hypocretinergic - Silent

Front 17

Thalamocortical activity during wakefulness and REM sleep is characterized by what? NREM sleep?

Back 17

A state of tonic activation and desynchrony; a state of rhythmic, synchronized activity

Front 18

What is the role of calcium channels in state-dependent thalamic activity?

Back 18

The transient Ca2+ current, It, enables thalamocortical neurons to generate a tonic firing pattern when stimulated from a relatively depolarized state or a burst-pause firing pattern when stimulated from a relatively hyperpolarized state

Front 19

How can arousal networks promoting wakefulness be divided?

Back 19

1. Ascending system

2. Stabilizing system

Front 20

Which nuclei are included in the ascending systems?

Back 20

1. Cholinergic nuclei of midbrain and pontine stegmentum

2. Monoaminergic brainstem neurons

3. Monoaminergic hypothalamic neurons

Front 21

The stabilizing system consists of?

Back 21

Hypocretinergic neurons of the perifornical and posterolateral hypothalamus

Front 22

Which neurons are responsible for the relative depolarization keeping the It channels inactive during wakefulness?

Back 22

Pedunculopontine and laterodorsal tegmental nuclei of the cholinergic ascending arousal network; tonic single-spike firing in response to afferent input facilitates transmission of sensory information to the cortex

Front 23

Which neurons are involved in the monoaminergic ascending arousal system?

Back 23

1. Noradrenergic neurons of the locus coeruleus

2. serotonergic neurons of the midbrain dorsal raphe

3. Dopaminergic neurons of the ventral periaqueductal gray

4. Histaminergic neurons of the hypothalamic tuberomammillary nucleus

Front 24

Which targets are innervated by the monoaminergic ascending arousal system?

Back 24

1. Cerebral cortex

2. Wake-stabilizing systems of the posteriolateral and perifornical hypothalamus

3. Sleep-promoting centers of anterior hypothalamus and basal forebrain

Front 25

How do the monoaminergic nuclei comprise 1 arm of the flip-flop switch between sleep- and wake-promoting centers?

Back 25

Direct inhibitory influences over the NREM sleep-generating neurons of the ventrolateral preoptic nucleus (VLPO) and median preoptic nucleus (MnPN)

Front 26

Which neurons comprise the stabilizing arousal system?

Back 26

Neurons in the posterolateral and perifornical region of the hypothalamus; these neurons express hypocretin ( orexin)

Front 27

Encephalitic patients with severe insomnia often have lesions where?

Back 27

Areas involving the preoptic area of the anterior hypothalamus

Front 28

Depletion of _____ results in persistent hypersomnolence and ___

Back 28

hypocretin nuclei of the posterolateral hypothalamus; intrusion of elements of REM sleep into wakefulness

Front 29

How is the hypocretin arousal system activated?

Back 29

Largely via glutaminergic input from the dorsomedial nucleus of the hypothalamus (DHM), which in turn is regulated by circadian inputs from the suprachiasmatic nucleus (SCN) and ventral subparaventricular zone

Front 30

The two most important brain regions fore generation and maintenance of sleep?

Back 30

1. Anterior hypothalamus (and adjacent basal forebrain)

2. Pontine tegmentum

Front 31

Specifically which brain regions are involved in the mediation of NREM sleep?

Back 31

Proptic nuclei of the anterior hypothalamus, including VLPO and MnPN

Front 32

Specifically which brain regions are involved in the mediation of REM sleep?

Back 32

Pontine tegmental nuclei, including the subcoeruleus region of the lateral nucleus reticular pontins oralis (NRPO)

Front 33

Which parts of the brain can be considered the somnogenic part of the flip-flop switch of wakefulness?

Back 33

The preoptic area nuclei, as well as the substantia innominata and diagonal band nucleus of the basal forebrain, as their widespread GABAergic and galaninergic projections inhibit the monoaminoergi, cholinergic, and hypocretinergic arousal nuclei

Front 34

Difference between VLPO neurons and MnPN neurons in firing pattern during sleep?

Back 34

VLPO most active during NREM, MNPN most active in early NREM, especially after prolonged wakefulness, suggesting MnPN activity induces NREM sleep, which VLPO then sustains

Front 35

What regulates the state transition between REM and NREM sleep?

Back 35

REM-on cells of the subcoeruleus region in the lateral NRPO and REM-off cells of other parts of the lateral pontine tegmentum and ventrolateral periaqueductal gray; these poles are mutually inhibitory

Front 36

What are the basic influences on sleep and wake patterns?

Back 36

1. Homeostatic

2. Circadian

3. Allostatic forces (unpredictable environmental influences)

Front 37

What is the primary function of the homeostatic force? What is it termed?

Back 37

Process S; maintain equilibrium between wake and sleep times, can be viewed as sleep debt

Front 38

Possible primary substrate for process S?

Back 38

Adenosine; may exert depolarizing or hyperpolarizing influence on target cell membranes, depending on the receptor subtypes

Front 39

What is a zeitgeber?

Back 39

Rhythmically occurring natural phenomenon which acts as a cue in the regulation of the circadian rhythm