COGS 17 - Midterm 3

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What is the Reticular Formation?

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407 Terms

1

What is the Reticular Formation?

A net-like structure from Medulla & Pons throughout Forebrain; receives from all sensory systems.

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2

What does the Reticular Formation do?

Alerts brain, stimulating Thalamus and Basal Forebrain via ACh and Glutamate.

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3

What is the Locus Coeruleus?

Part of Reticular Formation in Pons, especially active during new task & during vigilance.

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4

What does the Locus Coeruleus release?

Bursts of Norepinepherine (NE).

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5

What do Amphetamines do?

Increase alertness and activity by acting as NE-agonists.

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6

What is the Basal Forebrain?

Just anterior and dorsal to Hypothalamus, releases ACh throughout cortex for arousal & GABA to inhibit cortex.

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7

What is the implication of damage to Basal Forebrain?

It is implicated in Alzheimer's Disease; arousal is critical to memory activation.

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8

What is Adenosine?

A by-product of cell metabolism, builds up throughout the day, released in the brain, inhibits Basal Forebrain's release of ACh.

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9

What does Adenosine allow?

GABA connections to dominate, suppressing cortical activity, promoting sleep.

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10

What is the effect of caffeine on Adenosine receptors?

It blocks Adenosine receptors, allowing Basal Forebrain to continue to arouse the brain.

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11

What is Orexin?

An excitatory NT from Lateral Hypothalamus that helps maintain arousal in above systems.

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12

What does Orexin take into consideration?

Homeostatic conditions (hunger, thirst, temperature, sleep needs etc.).

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13

What is an Electro-Encephalogram (EEG)?

Used to characterize brain activity during different states of wakefulness/sleep

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14

What does EEG record?

Frequency (# changes in average potential/time) & Voltage (average amplitude)

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15

What is Beta Activity?

18-24 Hz, very high frequency, very desynchronized, awake and active

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16

What is Alpha Activity?

8-12 Hz, somewhat lower frequency, somewhat desynchronized, awake and relaxed

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17

What is Theta Activity?

4-7 Hz, lower freq, still quite irregular, significantly more synchronized, Sleep 1

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18

What are Spindles and K Complexes?

Intermittent bursts of high freq and/or voltage, as brain settles into deeper sleep. K Complex = Brief period of Delta activity. Spindles = Help gate external stimuli from reaching cortex

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19

What is Delta Activity?

< 4 Hz observed in less than 50% of this stage, very low freq, higher voltage, very synchronized, Sleep 3 and 4

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20

What is Slow Wave Sleep (SWS)?

Stages 3 and 4, Delta Activity in more than 50% of this stage, hardest to wake

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21

What happens to frequency and voltage as we move into deeper sleep?

Frequency decreases and voltage increases as brain activity becomes synchronized

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22

What happens to heart rate and breathing rate as we move into deeper sleep?

They decrease

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23

What happens to brain responsiveness to external stimuli as we move into deeper sleep?

It decreases

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24

What is REM sleep?

Rapid Eye Movement sleep, characterized by desynchronized EEG, atonia, and dreaming.

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25

What is atonia?

Loss of muscle tone throughout most of the body during REM sleep.

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26

What inhibits motor neurons during REM sleep?

The medulla, which is signaled by the pons.

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27

What happens to external stimuli during REM sleep?

They are detected and may be incorporated into dreams.

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28

What is the sleep cycle?

90 minutes from Stage 1 to REM: Stage 1, 2, 3, 4, 3, 2, REM, 2, 3, 4, 3, 2, REM, 2, 3, 2, REM, 2, REM...

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29

What happens to Stage 4 and Stage 3 as the night goes on?

Stage 4 becomes shorter and drops out after 2-3 cycles, then Stage 3 drops out.

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30

What happens to REM as the night goes on?

It becomes longer.

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31

What are the effects of sleep deprivation?

Lethargy, poor concentration, irritability, increased temperature, metabolism, and appetite, decreased resistance to infection.

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32

What is REM rebound?

When allowed to sleep after REM deprivation, there is an increase in the amount and duration of REM sleep.

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33

What happens when someone is continuously deprived of REM sleep?

They may become irritable, have poor concentration, anxiety, psychosis, hallucinations, and even death.

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34

What is the function of sleep and dreaming?

Controversial.

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35

What is the EEG like during REM sleep?

Desynchronized, high frequency, low voltage.

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36

What happens to heart rate, breathing rate, and blood pressure during REM sleep?

They become more variable than in other sleep stages.

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37

What happens to postural muscles during REM sleep?

They become paralyzed.

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38

What is the relationship between REM sleep and dreaming?

Highly correlated, but not 100%.

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39

What is an example of dream imagery in another sleep stage?

Night terrors, which occur during Stage 4.

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40

What areas of the cortex are often active during REM sleep?

Higher sensory areas.

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41

What is the role of the tegmentum during REM sleep?

Activation of cranial nerves for rapid eye movement.

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42

Why is sleep restorative?

Not clear

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43

Why can some species sleep less than others?

Unclear, but prey sleep less than predators

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44

What is the role of the Hypothalamus nuclei in sleep?

Initiating & regulating sleep

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45

What is the function of VLPOA in sleep?

Inhibits Brainstem and Cortex via GABA

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46

What does the Tubero-Mammillary Body of Hypothalamus release?

Excitatory Histamine 1 after periods of Slow Wave Sleep

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47

What is PGO Wave?

Sequence of activation in Pons => (Lateral) Geniculate => Occipital Cortex - initiates REM

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48

What is the role of ACh in sleep?

Initiates PGO Wave and arouses visual (& other sensory/motor) pathways

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49

What is the function of Raphe Nuclei in sleep?

Decreasing Serotonin (5HT) output > sleepiness, irritability if not sleep

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50

What is the role of 5HT in sleep?

Produces sudden, strong burst of 5HT, shuts REM off

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51

What is the function of Suprachiasmatic Nucleus (SCN) of Hypothalamus?

Circadian Clock

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52

What is the free-running rhythm in humans?

Activity/rest of ~ 24 +/-1 hours

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53

What is the interaction between SCN & Pineal Gland?

Regulates sleep and arousal systems

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54

What is the effect of damage to Raphe Nuclei?

No sleep

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55

What is the effect of Basal Forebrain arousal/de-arousal?

Enters thru anterior cortex

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56

What is the effect of ACh during REM?

Arouses (desynchronizes) visual (& other sensory/motor) pathways

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57

What is the effect of 5HT during sleep?

Very low during sleep, none during REM

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58

What is the effect of 5HT after REM?

Gradually falls, shifting system back into Slow Wave sleep

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59

What is the effect of ACh before and after REM?

Builds up just before REM, holds steady during, then drops off radically as REM ends

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60

What is the effect of the Pre-Optic Hypothalamus's assessment of fall in brain temperature?

Possibly initiates PGO Wave

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61

What is the effect of the interaction of different types & sources of neural activity?

Controls stages of sleep

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62

What is the effect of SCN in humans?

Establishes free-running rhythm of activity/rest of ~ 24 +/-1 hours

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63

What is the effect of replacing SCN in adult hamster with fetal SCN cells from 20-hour-cycle strain?

Hamster will adopt 20 hour cycle

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64

What are the functions of the Hypothalamus?

Releases hormones into bloodstream & projects to other Hypothalamic Nuclei, Brainstem, Pituitary glands

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65

How is the cycle regulated?

Through projections to and from Pineal Gland

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66

Where is the Pineal Gland located?

Just superior to midbrain, posterior to Thalamus

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67

What is the daily cycle of production of hormone Melatonin?

Shows daily cycle of production of hormone Melatonin which increases sleepiness

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68

What is the role of Melatonin in regulating the cycle?

SCN has receptor sites for Melatonin, so when Pineal increases Melatonin output at end of day, helps regulate cycle

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69

How can Melatonin be used as a sleep aid?

Melatonin can be taken as sleep aid a few hours before bed, helps reset clock (e.g. anti-Jet Lag)

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70

What is Seasonal Affective Disorder (SAD)?

Less light in winter, some people over-produce Melatonin; Light therapy can help

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71

What is the role of Retino-Hypothalmic Path in regulating the cycle?

First light of day to SCN via Retino-Hypothalmic Path produces inhibitory output to Pineal

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72

What is Zeitgeber?

Together, above interaction becomes your Zeitgeber = "Time Giver"

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73

How can the clock be reset?

Possible to reset clock, via exposure to bright light, strenuous exercise, seasonal or travel-based changes etc.

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74

What are the receptors in Retina that react to light?

Receptors in Retina (not Rods or Cones but specialized Ganglions!) w/photopigment Melanopsin react to light

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75

Where do the axons of these receptors synapse?

These Receptor's axons synapse in SCN (not in retina or thalamus!) via collateral of Optic Nerve

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76

What is Retino-Hypothalamic-Path?

Retino-Hypothalamic-Path

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77

What is the function of the hypothalamus?

Controls endocrine systems via pituitary gland

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78

What are releasing hormones?

Hormones that stimulate the anterior pituitary gland to release its own hormones

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79

What are the other hormones produced by the hypothalamus?

Oxytocin and other hormones sent via axons to posterior pituitary

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80

What are the organizing effects of reproductive hormones?

Effects on anatomy in fetal development and puberty

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81

What are the activating effects of reproductive hormones?

Influence behavior

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82

Do both sexes have female and male hormones?

Yes, in different proportions

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83

Where are steroid hormones produced?

Mainly in ovaries/testes, also in hypothalamus and adrenal glands

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84

What determines gender?

Hormone activity, not just sex chromosomes

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85

What are the anatomical precursors for both sexes in every mammalian fetus?

Gonads

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86

What is the earliest sex structure to develop?

Gonads

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87

What are the same initial structures in all fetuses that develop into male or female anatomy?

Genitalia

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88

What are Wolffian and Muellerian ducts?

Internal sex organs precursors

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89

What determines the development of Wolffian and Muellerian ducts?

Androgens

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90

What do Wolffian ducts and Muellerian ducts become?

Vas Defrens & Prostate or Fallopian Tubes & Uterus respectively

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91

What happens to the other duct system that is not developed?

It degenerates

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92

What genes control male/female body & brain development?

Present in both sexes

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93

What is the 'switch' that determines male/female development?

Male's Y Chromosome

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94

What is the enzyme produced by the Testis-Determining Factor (TDF) Enzyme?

TDF

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95

When does TDF appear during fetal development?

6th-8th week

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96

When are genitals developed?

By 4th month

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97

What happens if TDF is not present?

Ovaries differentiate, Mullerian system develops, Wolffian regresses, female genitalia develop regardless of genotype

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98

What happens if the fetus is XY but lacks the specific gene for TDF?

It will develop internally & externally as female

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99

What happens if the fetus is XO (Turner's Syndrome, no Y Chromosome)?

It will develop internally & externally as female

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100

What is the result of both non-XX fetuses?

Infertile

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