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Neuro 4623: Behavioral & Molecular Biological Clocks > SAMPLE FINAL PLUS PRACTICE MIDTERMS > Flashcards

SAMPLE FINAL PLUS PRACTICE MIDTERMS Flashcards

1
Q

Bright daylight can influence:

a. Amount of melatonin secreted in humans
b. Phase of onset of melatonin secreted in humans
c. Phase of onset of activity in hamsters

A

All of the above

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2
Q

If free running hamsters in constant lighting conditions are given a light pulse during the middle of the subjective day, this will:

A

Have little or no effect on the activity rhythm

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3
Q

Evidence from Hamsters suggests that the activity-rest circadian rhythm can be entrained to any period within:

A

18-26 hours

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4
Q

Biological rhythms observed in constant environmental conditions are said to be __________.

A

Free-running

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5
Q

If an appropriate __________________ is given, the rhythm is said to become _________________ to environmental conditions.

A

Zeitgeber, Entrained

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6
Q

In an early experiment by de Mairan, a mimosa plant was placed in a dark cabinet and temperature was held approximately constant.
The plant continued to show a daily rhythm of leaf movements, with leaves open during the day and folded at night.
This result indicates most conclusively that:

A

the natural daily rhythms of light and temperature are not required for rhythmic leaf movements

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7
Q

An experiment by de Candolle showed that the rhythmic leaf movements of the mimosa plant continued in constant darkness with a period length that was not exactly 24h.
This type of observation helped to convince biologists that:

A

some daily rhythms are driven by internal, self-sustained oscillators

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8
Q

A common feature of circadian, circannual, circatidal, and circalunar rhythms is that all of them:

A

are related to geophysical rhythms that may have some importance to organisms

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9
Q

As compared to homeostatic processes, biological rhythms seem to be much less dependent on:

A

internal negative feedback mechanisms

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10
Q

For a Nocturnal animal that is free-running under constant conditions, the beginning of the active phase (locomotor activity) corresponds approximately to:

A

beginning of subjective night (??)

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11
Q

The term “temperature compensation” is most clearly illustrated by the observation that:

A

mean environmental temperature has little effect on taudd

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12
Q

Differences between individuals of a species with respect to tau:

a. may result from genetic differences
b. may be a result of different photoperiod histories of the individuals
c. may be related to age
d. do not exist
e. “a” , “b”, and “c”

A

e.

“a” , “b”, and “c”

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13
Q

Rodents are most likely to become arrhythmic (non-rhythmic) when exposed to:

A

continuous light (LL)

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14
Q

If you wanted to estimate the limits of entrainment to light/dark cycles for a particular species, which of the following would provide helpful information:

A

the phase response curve and tau

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15
Q

For people on a normal day-night schedule, cortisol levels peak in the______________ and are lowest in_________________.

A

Early morning; early evening

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16
Q

The last link in the pathway to the pineal gland comes from the:

A

Superior cervical ganglia

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17
Q

All of the following are involved with mammalian photoperiodism except the

a. Pineal gland
b. Suprachiasmatic nucleus (SCN)
c. GnRH neurons
d. Hippocampus

A

Hippocampus

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18
Q

The Aschoff Rule states that

A

light intensity affects the period of a rhythm

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19
Q

A phase response curve (PRC) best describes

A

a rhythm’s entrainment properties

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20
Q

Which of the following exhibits clock properties in birds?

a. Suprachiasmatic nucleus
b. Pineal gland
c. The retina of the eye
d. both a and b
e. a, b, and c

A

d. both a and b

Suprachiasmatic nucleus,
Pineal gland

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21
Q

In general, seasonal reproduction in various avian and mammalian species is usually regulated by one of the following factors, but NOT

a. photoperiod
b. food availability
c. a circannual rhythm
d. temperature

A

Temperature

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22
Q

The critical feature of pineal gland function that causes short-day-induced gonadal regression in rodents is:

A

the duration of the daily melatonin rhythm

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23
Q

Biological clocks are involved in all of the following events, EXCEPT

a. the sun-arc hypothesis
b. photoperiod time measurement
c. night orientation to star patterns
d. the hibernation cycle of the ground squirrel
e. the feeding cycles of voles

A

night orientation to star patterns

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24
Q

Infradian rhythms refer to those rhythms with a period

A

that is more than 24 hours

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25
Q

What is the single most defining characteristic of a true biological rhythm?

A

that it is self sustaining

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26
Q

Which region of the mammalian brain is viewed as the master clock that organizes all circadian rhythms?

A

suprachiasmatic nucleus

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27
Q

Which of the following list of biological rhythms is ordered from most frequent (shortest) to least frequent (longest)?

A

ultradian, circadian, infradian, circannual

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28
Q

What is photoperiodism?

A

the ability to use day length to time annual cycles

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29
Q

List 5 characteristics of biological clocks:

A

…

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30
Q

Describe the two ways that biological clocks allow animals to adapt to temporal fluctuations:

A

…

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31
Q

What is the relationship of the circadian system to the ovulatory cycle in rats and hamsters?

A

…

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32
Q

Briefly describe and evaluate the experimental evidence that the SCN is an important neural clock in mammals.
In the second part of your answer propose what you think is the most important next step to understand SCN function as a neural pacemaker.
Defend your choice and provide a brief experimental approach as to how you would address the problem.

A

…

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33
Q

VIP-expressing neurons are found in which region of the SCN?

A

Core

  • weak rhythm
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34
Q

TRUE or FALSE?

Period 1 and Period 2 dimerize to drive the expression of Clock and Bmal1.

A

FALSE

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35
Q

2-Deoxyglucose labeling was used to determine ________.

A

The locus of the master clock

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36
Q

The Bulla gouldiana model system was used to show that ________ .

A

Protein synthesis rates set clock period length

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37
Q

The E-Box binds to which transcription factor?

CRY
ERK
Leucine Zipper
CREB

A

none of the above

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38
Q

Which of the following approaches was used to test Period 1 and Period 2 functionality in the circadian clock?

A

Gene Knockout

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39
Q

What neurotransmitter is expressed in both the core and the shell of SCN

A

GABA

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40
Q

ENU causes which type of mutations?

A

A to T

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41
Q

In the absence of any information regarding the molecules underlying a physiological process, what genetic approaches could be used to begin to identify the relevant genes?

A

Forward genetics

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42
Q

Which region of Clock protein allowing for protein‐interactions?

A

PAS domain

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43
Q

Within the core clock transcription/translation feedback loop, Period protein would be considered which type element?

A

Negative element

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44
Q

Clock mutation heterozygous mice exhibit what circadian phenotype?

A

Long rhythm

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45
Q

What was the effect of the Tau mutation on period length?

A

Shorter

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46
Q

Which of the following compounds inhibit sleep?

A

orexin

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47
Q

Loss of orexin neurons is associated with

A

daytime sleepiness

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48
Q

What would be the effect of 30 minutes of light on a hamster’s wheel running behavior if the hamster was kept in total darkness and the behavior was free-running?

A

It would depend on when in the animal’s subjective night that the light was turned on.

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49
Q

What would one expect to happen if the zeitgeber was removed from a group of rats?

a. there would be no effect of removing the zeitgeber
b individual rats would be active consistently earlier or later every day
c. there would be a phase advance in the rats’ activity onset
d. there would be a phase delay in the rats’ activity onset

A

Individual rats would be active consistently earlier or later every day.

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50
Q

Which of the following statements is false?

a. melatonin at high doses (>100 mg) is toxic
b. the precursor for melatonin is serotonin
c. melatonin may inhibit aging
d. melatonin activates glutathione peroxidase

A

melatonin at high doses (>100 mg) is toxic

51
Q

If a male hamster is kept in short days (10 hrs light & 14 hrs dark) indefinitely, it will

A

spontaneously exhibit testicular growth after several months

52
Q

Mammals, flies, fungi and cyanobacteria all have transcriptional clocks that work in a similar way, although has a different pair of genes. In mammals, the genes are

A

BMAL/Clock

Per and CRY

53
Q

Photoperiodism in different organisms affects the timing of different physiology, but the one that is most universally affected is:

A

reproduction

54
Q

“Photo” of photoperiodism refers to :

A

light

55
Q

If you had a plant that was being consumed by a fast reproducing bug called bugerosus, and you found on the internet that the critical dark period for bugerosus’ reproductive cycle is 5 hours, then you could conceivably control the bug by:

A

Leaving the lights on for 20 hours each day and off for 4 hours

56
Q

The testes eventually develop in male hamsters even if they remain in constant dark condition. This observation demonstrates that testicular development is also controlled by:

A

a circannual rhythm.

57
Q

Rodents are most likely to become arrhythmic (non-rhythmic) when exposed to:

A

continuous light (LL)

58
Q

If you wanted to estimate the limits of entrainment to light/dark cycles for a particular species, which of the following would provide helpful information:

A

the phase response curve and tau

59
Q

A common feature of circadian, circannual, circatidal, and circalunar rhythms is that all of
them:

A

Are related to the period of the earth’s rotation about its own axis

60
Q

Deletion of the clock gene has what effect on Period 1 expression.

A

Repressed

61
Q

The Period mutation was first characterized in _______ .

A

Drosophila

62
Q

Which effect would blocking Period protein nuclear translocation have on the Period gene expression?

A

suppressed expression

63
Q

Which effect does the Tau mutation have on casein kinase 1 activity?

A

stimulates

64
Q

PAS Domains are found in which of the following proteins:

a. period
b. clock
c. BMAL
d. none of the above
e. all of the above

A

all of the above

65
Q

In butterflies, cryptochromes were shown to function in:

A

magnetic field-based navigation

66
Q

What finding suggested that clock cell communication is essential for the phase-coherent output of the SCN?

A

the varied periodicity of isolated SCN neurons

67
Q

VIP binds to what type of receptor?

A

G-protein coupled receptor

68
Q

Bmal1 and Clock:

A

drive the rhythmic expression of clock output genes

69
Q

Which two intracellular signaling effectors are NOT downstream of VIP in the SCN?

A

PKG and AMPK

70
Q

Which two intracellular signaling effectors are downstream of VIP in the SCN?

a. calcium
b. PKG
c. AMPK
d. cAMP

A

calcium, cAMP

71
Q

The retinohypothalamic nerve terminal is:

A

glutamatergic

72
Q

Early life circadian rhythms can be restored to pups of SCN-lesioned dams with the administration of:

a. melatonin
b. dopamine receptor agonists
c. temperature fluctuations
d. a and b
e. all of the above

A

a and b

melatonin and dopamine receptor agonists

73
Q

An intact maternal SCN is necessary for all of the following EXCEPT:

a. rhythms of 2DG in the fetal SCN
b. rhythms of NAT activity in the 10 day old animal
c. the phase of entrainment of the pups
d. the cycle length (tau) of the pups
e. intact maternal SCN is necessary for all of the above

A

d. the cycle length (tau) of the pups

74
Q

TRUE or FALSE?

Cycling clock genes can be detected in fetal rat SCN by prenatal day 10.

A

false

75
Q

TRUE or FALSE?

Cycling clock genes can be detected in fetal rat SCN by embryonic day 19.

A

true

76
Q

Circadian rhythmicity can be detected in fetal animals by all techniques EXCEPT:

a. measuring wheel running activity
b. assessing radioactive glucose uptake in the SCN
c. Measuring N-acetyl transferase expression
d. assessing clock gene expression
e. all of the above

A

measuring wheel running activity

77
Q

Which 2 intracellular signaling pathways were shown to oscillate in the SCN:

a. PKG
b. PKM
c. cAMP
d. cGMP
e. cTKP
f. calcium
g. potassium
h. nitrogen

A

cAMP and calcium

78
Q

How do oscillations in intracellular signaling pathways regulate the core molecular oscillations?

A

amplification of Period 1 transcription

79
Q

Light pulses delivered at the following times have what effect of circadian clock phase?

A

Early subjective night: Phase Delay

Late subjective night: Phase Advance

Mid-subjective day: Nothing

80
Q

Photic stimulation during the mid-subjective day has what effect on MAPK expression?

A

no effect

81
Q

List 3 effects that constant light has on overt rhythms -

A
  • arrhythmia
  • tau lengthens
  • split rhythm
82
Q

At the level of the molecular clock, photic resetting is caused by a rapid increase in the expression of:

A

???!!

83
Q

Constant light-induced splitting of locomotor activity results from:

A

????!!

84
Q

Phase of activity nrhythms in pups match that of the mother except when the mother is __________ .

A

SCN lesioned

85
Q

Disruption of cAMP levels had what effect on Period 1 luciferase rhythms.

A

Damped.

86
Q

The melanopsin receptor is activated by which light color?

A

??!?!!

87
Q

Melanopsin is expressed in which type of cell?

A

Retinal ganglion cells

88
Q

Which transcription factor couples the MAPK pathway to the core molecular clock?

a. E-Box
b. CREM1
c. NPAS
d. CREB
e. TORC1
f. Bmal1
g. Clock

A

CREB

89
Q

Blind-Sight refers to ….

A

the ability to use non-image-forming visual circuits to navigate in space.

90
Q

A novel wheel triggers resetting of the circadian clock by triggering.

A

…..???!!!

91
Q

In the experiments that examined MAPK signaling and light-evoked click resetting, U0126 was used to

A

…..???!!!

92
Q

Dopamine agonists induce _______ expression in the SCN.

It therefore acts as a signal of _________ .

A

Dopamine agonists induce c-fos expression in the SCN.

It therefore acts as a signal of daytime.

93
Q

TRUE or FALSE?

Infusing high continuous levels of GnRH produces greater production of LH and FSH than intermittent infusion.

A

FALSE

94
Q

The best evidence that SAD does not merely reflect the “holiday blues” is:

A

the symptoms are 6 months out of phase in people inhabiting the southern hemisphere

95
Q

GnRH infused in which pattern will give the maximal pituitary gonadotropin response?

A

Pulsatile administration

96
Q

Circadian rhythms do not appear to mediate the preference for song length in Drosophila
because

A

Per mutations do not change song preference despite altering song production and
circadian rhythms

97
Q

TRUE or FALSE?

There are more traffic accidents the day after both the spring and fall time shifts for day lights savings.

A

FALSE

98
Q

All of the following appear to be able to synchronize circatidal rhythms in crabs except:

A

Inundation

99
Q

Heavy water (D2O) alters

A

Circadian but not ultradian rhythms

100
Q

The apparent role of the-SCN axis in the control of growth hormone release is

A

When the SCN is lesioned GH release continues but is no longer synchronized to the light/dark cycle

101
Q

The human menstrual cycle likely evolved to be the same length as the lunar cycle because….

A

***There is no apparent relationship between the length of the lunar and menstrual cycles.

OR

It would be advantageous to be most fertile when the moon is full so it is easier to find

102
Q

Seasonal affective disorder is characterized by all of the following except

  1. impaired retinal function
  2. shorter melatonin duration
  3. seasonal patterns of recurrence
  4. treatment with light or SSRIs can relieve symptoms
A

impaired retinal function

103
Q

Heart attacks and strokes are most common in the

A

9am

104
Q

Nuclear hormone receptors act in an ‘accessory loop’ to influence clock and metabolic function:

A

REV-ERBs (repressors)
RORs (activators)

They bind retinoic acid-related orphan receptor response elements (ROREs) at the Bmal1 promoter.

RORα and REV-ERBα respond to metabolic status and are targets of CLOCK:BMAL1
REV-ERBα is induced during adipogenesis

105
Q

Deletion of REV-ERBα leads to altered metabolism and obesity.

A

Cold stress rapidly downregulates Rev-erbα

Rev-erbα orchestrates the daily rhythms of body temperature

106
Q

Nuclear receptors both sense and respond to the environment!

A

Metabolic status and the circadian clock are fundamentally and dynamically linked

107
Q

Nampt

A

important for cellular metabolism; insulin mimic, synthesizes redox proteins, levels correlate with adipose tissue

is a transcriptional target of CLOCK:BMAL1.

108
Q

SIRT1

A

regulates insulin sensitivity

suppresses CLOCK:BMAL1 transcription

109
Q

Adenosine monophosphate-activated protein kinase (AMPK)

A

increases cellular energy uptake in response to energy use

directly regulates the clock by phosphorylating CRY1

110
Q

Without an SCN to provide input, peripheral cells gradually fall out of phase with each other.
There are two striking exceptions to this:

A
  • Scheduled, restricted feeding
  • Chronic administration of methamphetamine

Both are capable of organizing circadian outputs in the absence of the SCN.

111
Q

Food Entrainable Oscillator (FEO)

A

SCN lesioned animals can still entrain to timed food restriction (TFR).

Interestingly, the FEO does not seem to require a functional molecular clock (Bmal-/- and Per1/Per2-/- can entrain to TFR).

Controls peripheral clocks and body temperature

Food entrainable oscillator is set by feeding, NOT SCN

112
Q

Food Anticipatory Activity (FAA)

A

Food anticipatory activity (increases in activity) is observed prior to short meals presented at a scheduled time of day

113
Q

FAA Persists Following Multiple Brain Lesions

A

Lesioning of Hippocampus,
Hypothalamus (including SCN)
Cortex, And others…
….does not affect FAA

114
Q

Leptin – A Satiety Signal

A

Leptin is a negative regulator of hunger

High leptin = less hunger*

Normally peaks at night

Increases with adipose tissue
levels and insulin levels

Leptin resistance —> obesity

115
Q

“Outputs” (e.g., behavior or temperature) become “inputs” for other oscillators.

A

Reciprocal connections exist between the circadian and metabolic system.

Circadian mutants (or disregulated circadian systems) have metabolic problems, and nutrient intake can influence circadian rhythms.

116
Q

Three determinants of sleep

A
  1. Sleep homeostasis
    – The longer since you’ve slept the easier sleep
    comes
  2. Circadian rhythms
  3. Social Timing
117
Q

Sleep

A 
– Universal among higher vertebrates
–Sleep deprivation, devastating
– One-third of lives in sleep state
– Defined: “Sleep is a readily reversible
state of reduced responsiveness to, and
interaction with, the environment.”
118
Q

STAGES OF NON-REM SLEEP

A

Stage 1 – Beginning of sleep cycle – light sleep lasting about 5-10 minutes.

Stage 2 – Bursts of rapid, rhythmic brain activity. Body temperature starts to decrease and heart slows.

Stage 3 – Deep, slow brain waves begin to emerge. Transition between light and very deep sleep.

Stage 4 – Slow wave or Delta Sleep. Deep sleep lasting ~ 30 minutes. EEG shows synchronized delta waves

119
Q

PARADOXICAL or REM SLEEP

A

About every 90-120 minutes there is a shift to desynchronized sleep in which thalamic neurons return to
tonic mode.

EEG is dominated by low-voltage, high frequency activity that is similar to the activity seen in waking state.
Individual is very hard to wake up during this stage – paradoxical sleep
Abolition of muscle tone
Although muscle tone is inhibited, eye movement breaks through and there is rapid movement of the eyes (REM)
Transmission of impulses over sensory pathways is greatly decreased
Blood pressure rises a little
Heart rate and breathing become erratic
Hypothalamic regulation of body temperature is lost
Period when dreams occur
Large areas of cortex are active. Sensory input is blocked, therefore no motor activity

120
Q

• Sleep-Promoting Factors

A

– Muramyl dipeptide: isolated from the CSF of sleepdeprived
goats, facilitates non-REM sleep

– Interleukin-1: Synthesized in brain (glia,
macrophages), stimulates immune system
– Adenosine: Sleep promoting factor; released by
neurons; may have inhibitory effects of diffuse
modulatory systems
– Melatonin: Produced by pineal gland, released at
night-inhibited during the day (circadian regulation);
initiates and maintain sleep; treat symptoms of jet lag
and insomnia

121
Q

Sleep Disorders

A

• Insomnia
– Disorder in going to sleep or staying asleep

• Narcolepsy
– Sleep intrudes into waking period

• Sleep apnea
– Intermittent cessation of breathing

• Motor Disturbances
– Sleep walking
– Sleep talking
– Tooth grinding
– Night terrors
122
Q

NARCOLEPSY

A

Sudden onset of sleep including REM sleep

Can include REM “fragments” during awake state
– Hypnogogic hallucinations (wakeful dreaming)
– Muscle atonia (cataplexy)

Effects 2-5 / 10,000
– Associated with loss of orexin or receptors
– Orexin is neuropeptide found in hypothalamus that is critical for arousal

123
Q

Light at Night (LAN)

A

Drama-c changes in our temporal life since ar-ficial
light was invented over 130 years ago.

• Widespread adop-on of this technology occurred
BEFORE much was known about the importance of
biological clocks orchestra-ng homeostasis.
• Although, ar-ficial light brought great economic
prosperity and changed human life styles, the results
of several experiments show that excessive exposure
to light at night (LAN) reduces the secre-on of the
pineal hormone melatonin (MLT), the physiological
signal of dark.

124
Q

Excessive exposure to light at night (LAN) reduces the secre-on of the
pineal hormone melatonin (MLT), the physiological
signal of dark.

A

BMI is Positively Associated With Moderate/Severe Depression

Dim LAN Increases Body Mass and Adiposisty

LAN Impairs Glucose Processing

Timing of Food Intake in Mice Exposed to
Bright and Dim LAN Differed

Neuro 4623: Behavioral & Molecular Biological Clocks (11 decks)

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