Nsp Week 3: Circadian Rhythms (Blair)

Front 1

What is the major circadian pacemaker in the brain?

Back 1

Suprachiasmatic Nucleus (SCN)

Front 2

Where is the suprachiasmatic nucleus located?

Back 2

Anterior hypothalamus
(directly above the optic chiasm)

Front 3

If there are no external time cues, the SCN cycle runs on an average of hour many hours?

Back 3

24.2 hours

Front 4

Describe the action of the neurons in the SCN.

Back 4

Each neuron in the SCN has molecular machinery that produces a rhythmic oscillation in gene transcription and translation that occurs during a day

Front 5

Describe the action of the SCN on the hypothalamus and the pineal gland

Back 5

Signals growth hormone secretion in the hypothalamus and melatonin production in the pineal gland

Front 6

What is the function of melatonin?

Back 6

Promotes sleep
(inversely related to the amount of light in the environment. Low light = high melatonin = sleepiness)

Front 7

What is the consequence of damage to the SCN?

Back 7

Uncoordinated biologic processes
(does not prevent cycling of biologic processes, but the processes will no longer have a circadian rhythmicity)

Front 8

How is the SCN entrained to the light-dark cycle?

Back 8

Retinohypothalamic pathway

Front 9

Describe the action of the ganglion cells in the Retinohypothalamic pathway

Back 9

Directly depolarized by light --> melanopsin changes conformation --> increased discharge of action potentials

*These cells course in the Optic N to the Optic chiasm, where they exit the chiasm to terminate in the nearby SCN.

Front 10

List the 3 components of consciousness

Back 10

1. Cognitive processes (cerebral cortex)
2. Attention (cerebral cortex)
3. Arousal and wakefullness (brainstem, thalamus)

Front 11

Lesions to which regions of the brain produce varying levels of consciousness?

Which system is affected?

Back 11

1. Brainstem
2. Thalamus

*Ascending Reticular Activating System (ARAS)

Front 12

Which portion of the brainstem is comprised of the reticular formation?

Back 12

Central core

Front 13

Which portion of the reticular formation is involved in the consciousness system?

Back 13

Formation in the midbrain and upper pons
(Pontomesencephalic or mesopontine reticular formation, or mesopontine tegmentum)

Front 14

Which structures do the reticular neurons project to?

Back 14

1. Thalamus
2. Basal forebrain
3. Cerebral cortex

Front 15

List the 4 neurotransmitter systems that contribute to arousal

Back 15

1. NE-serotonin-dopamine
2. ACh-glutamate
3. Histamine-orexin (hypocretin)
4. Intralaminar nuclei and other medial thalamic nuclei

Front 16

What is an EEG (electroencephalogram) used for?

Back 16

1. Diagnosis of localized/generalized lesion induced by trauma, infection, etc.
2. Used as an index of brain (specifically cortical) death.

Front 17

List the 4 wave patterns and their frequencies

Back 17

Beta >13 Hz (smallest amplitude)
Alpha 8-13 Hz (small amplitude)
Theta 4-7 Hz (small amplitude)
Delta < 4 Hz (large amplitude

Front 18

What level of consciousness is the beta wave pattern associated with?

Back 18

Awake state with eyes open
(>13 Hz, smallest amplitude)

Front 19

What level of consciousness is the alpha wave pattern associated with?

Back 19

1. Awake state w/ eyes closed
2. drowsy (stage 1)

(8 - 13 Hz; small amplitude)

Front 20

What level of consciousness is the theta wave pattern associated with?

Back 20

Light sleep (begin in Stage 1)
(4 - 7 Hz; small amplitude)

Front 21

What level of consciousness is the delta wave pattern associated with?

Back 21

Deep sleep (begin in Stage 4)
(<4 Hz, large amplitude)

Front 22

Which sleep waves are the least synchronized and which are the most synchronized?

Back 22

Least synchronized --> beta
Most synchronized --> delta

Front 23

What's the difference between the EEG patterns during NREM and REM sleep?

Back 23

NREM --> synchronized EEG
REM --> desynchronized EEG (resembles awake EEG)

Front 24

Describe the EEG pattern of an awake individual

Back 24

1. Desynchronized beta waves, alpha waves (mainly over occipital lobe when eyes are closed)
2. Random activity
3. High muscle activity

Front 25

Describe the EEG patterns seen in Stage 1

Back 25

1. Mostly alpha waves, some theta
2. High muscle activity
3. Drowsy

Front 26

Describe the EEG patterns seen in Stage 2

Back 26

1. Mostly theta, some delta waves
2. Special waves such as spindles and K complexes (due to burst pattern of thalamic neuronal activity)
3. Some muscle activity

Front 27

Describe the EEG patterns seen in Stage 3

Back 27

1. 1/2 theta, 1/2 delta waves
2. Low muscle activity

Front 28

Describe the EEG patterns seen in Stage 4

Back 28

1. >50% delta waves
2. Deep sleep
3. Minimal muscle activity

Front 29

Describe the EEG patterns seen in REM sleep

Back 29

1. Waves similar to awake
2. Little muscle activity

Front 30

What does the EEG represent?

Back 30

Summed synaptic potentials from the dendrites in the superficial layers of cortex

Front 31

The pyramidal cells are concentrated in which layers of the cortex?

Back 31

3 and 5

Front 32

Which layer of the cortex receives input from the thalamus?

Back 32

Layer 4

Front 33

Describe why the amplitudes are small and frequency is fast in the awake state

Back 33

Potentials arrive randomly at different times; therefore, little summation occurs

Front 34

What is the major determinant of the synchronized patterns in the EEG?

Back 34

Synchronized thalamic input to the cortex

Front 35

List 3 nuclei in the hypothalamus that control behavior state

Back 35

1. Ventrolateral preoptic area (VLPO)
2. Tuberomammillary nucleus (TMN)
3. Orexin neurons (no named nucleus)

Front 36

What is the major control center for sleeping?

Which neurotransmitters are secreted?

Back 36

Ventrolateral preoptic nucleus
(anterior portion of hypothalamus)

*GABA and galanin (inhibitory)

Front 37

What would be the result of a lesioned ventrolateral preoptic nucleus?

Back 37

Insomnia

Front 38

What affect does heat have on the neurons of the ventrolateral preoptic nucleus?

Back 38

Heat excites them
(sleep-inducing effect)

Front 39

Where is the tuberomammillary nucleus located?

Back 39

Posterior hypothalamus

Front 40

Where is the ventrolateral preoptic nucleus located?

Back 40

Anterior hypothalamus

Front 41

Which neurotransmitters are secreted by neurons in the tuberomammillary nucleus?

Back 41

Histamine and GABA

Front 42

When are neurons in the tuberomammillary nucleus active?

Back 42

During waking

Front 43

How do antihistamines cause sleepiness?

Back 43

By blocking the projections in the tuberomammillary pathway, which are responsible for waking.

Front 44

Where are orexin neurons located?

Back 44

Lateral hypothalamus

Front 45

What is the result of damage to the tuberomammillary nucleus?

Back 45

Excessive sleepiness

Front 46

Is orexin (hypocretin) excitatory or inhibitory?

Back 46

Excitatory

Front 47

Which neurons stabilize the sleep-control switch?

Back 47

Orexin (hypocretin) neurons

Front 48

What is the result of damage to the orexin (hypocretin) neurons?

Back 48

Narcolepsy
(episodes of sleep and wakefullness occur randomly throughout the day)

Front 49

List 4 nuclei in the brainstem

Back 49

1. Locus coeruleus (LC) and dorsal raphe nucleus (DR)
2. Laterodorsal tegmental nuclei (LTD) and pedunculopontine nuclei (PPT)
3. Pontine reticular formation
4. GABA neurons

Front 50

Which neurotransmitters do the locus coerulus and dorsal raphe nucleus secrete?

Back 50

LC --> NE
DR --> 5-HT

Front 51

Where are the locus coerulus and dorsal raphe nuclei located?

Back 51

Locus coerulus --> rostral pons
Dorsal raphe --> midbrain

Front 52

Which brainstem nuclei are active during waking?

Back 52

Locus coerulus & Dorsal raphe nucleus

Front 53

Which neurotransmitter is secreted by the Laterodorsal tegmental and Peduncopontine nuclei?

Back 53

Acetylcholine

Front 54

Where are the Laterodorsal tegmental and Peduncopontine nuclei located?

Back 54

Junction at the midbrain and pons
(mesopontine tegmentum)

Front 55

Which brainstem nuclei are particularly important for controlling REM sleep?

Back 55

Laterodorsal tegmentum & Peduncopontine nuclei

Front 56

Neurons from which region of the brain will produce atonia, pontine-geniculate-occipital (PGO) waves, and rapid eye movements associated with REM sleep?

Back 56

Pontine reticular formation

Front 57

What is the major role of GABA neurons in the sleep-wake cycle?

Back 57

Inhibition of LC and DR during REM sleep

Front 58

Which neurotransmitters are active in the awake state?

Back 58

Highest levels:
1. NE
2. 5-HT
3. HA
4. OR

Slightly lower level:
1. ACh

Front 59

Which neurotransmitters are most active in the Non-REM state?

Back 59

GABA (from VLPO)

(Lower levels: ACh > monoamines)

Front 60

Which neurotransmitters are the most active during the REM state?

Back 60

ACh

(Lower levels: GABA > > monoamines)

Front 61

Activation of which neurotransmitter in the brainstem initiates REM sleep?

Back 61

ACh

Front 62

Rapid eye movement and atonia originate from which area of the brain?

Back 62

Pontine reticular formation

Front 63

Which muscles are still functioning during REM sleep?

Back 63

1. EOM- Rapid eye movements
2. Muscles of the inner ear
3. Diaphragm

Front 64

How long does a sleep cycle last?

Back 64

90 minutes

Front 65

During which cycles are sleep stages the deepest?

Back 65

Early on-- 1st or 2nd cycle

Front 66

REM sleep is longest during which cycles?

Back 66

4th or 5th

Front 67

REM sleep follows which stage of the sleep cycle?

Back 67

Stage 2

Front 68

Which nuclei are as active during the awake state as they are during the REM state?

Back 68

Laterodorsal tegmental & Peduncopontine nuclei

Front 69

Which somnogen is thought to be the primary, if not only, somnogen that influences the sleep/wake cycle on a daily basis?

How does it work?

Back 69

Adenosine

*It accumulates in the basal forebrain in the area of the VLPO as a result of metabolic activity. As it accumulates, the excitatory drive on VLPO neurons increases until the "switch is flipped," and sleep ensues.

Front 70

What are the 3 major categories of sleep disorders?

Back 70

1. Insomnia
2. Hypersomnia
3. Parasomnia

Front 71

What is the medical term for sleep walking?

Which stages of sleep does this occur in?

Back 71

Somnambulism

*Stage 3 or 4 (slow-wave sleep)

Front 72

During which cycles of sleep do night terrors occur? Which stages?

Back 72

First or second cycle
*Stage 3 or 4

Front 73

When do incubus attacks usually occur?

Back 73

During stage 3 or 4 of the first cycle of sleep

Front 74

What type of sleep disorder is a cross between hypnogogic hallucinations and night terrors?

Back 74

Incubus attacks
*Person is terrified and recalls episodes

Front 75

What type of sleep disorder allows a patient to "act out" dreams?

Back 75

REM behavior disorder

(Dementia with Lewy Bodies)