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COGS 143 > Cetaceans: Brains > Flashcards

Cetaceans: Brains Flashcards

1
Q

Why does absolute brain size matter?

A

more matter = more connections

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2
Q

What is Encephalization Quotient (EQ)?

A

ratio of actual brain mass to expected brain mass of comparison animal, corrected for body size

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3
Q

What is special about the cerebellum for Tursiops?

A

bottlenose dolphins have largest relative size of any cerebellum of any mammal

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4
Q

What does the cerebellum do for cetaceans?

A

-area involved in movement of limbs, posture, head (visual tracking) REDUCED

  • areas controlling face, trunk and tail = ENLARGED
  • articulate vocalizations
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5
Q

Unlike primates who are altricial, cetaceans are ______ at birth

A

precocial (well developed)

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6
Q

Dolphins have ____ month gestation

A

12

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7
Q

Dolphin brain at birth is _____% of the adult brain

A

40

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8
Q

Human brain at birth is _____% of the adult brain

A

25

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9
Q

What is the importance of the impedance match of seawater and amniotic fluids for cetacean fetuses?

A

sound is able to impede vibration in different ways, possibly explains for extensive development of acoustic processing by brain

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10
Q

Cetacean auditory nerve has _____ times the fibers to humans

A

2.5

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11
Q

What is unique about the auditory system for cetaceans?

A

main source of info on shape, size, content, distance of stimuli

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12
Q

Cetaceans have what in their auditory nerve to increase transmission speed?

A

huge, myelinated fibers

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13
Q

The fact that the lateral lemniscus is 250x size humans, the inferior colliculus is 12x size humans, and the thalamus MGN 7x size of humans allows dolphins to what?

A

easily find where sounds are

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14
Q

Explain the dual processing system

A

brain stem = giant, broadband, brief, fast changing inputs

cortex = layers, intepreting sound => “Language”/higher cognitive processing

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15
Q

What is similar and different about the auditory system in humans and dolphins?

A

dolphins have same process but the proportions at each stage different

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16
Q

(True/False): Cetaceans have small amounts of fovea

A

FALSE; Cetaceans have NO fovea

BUT have dense, giant, myelinated ganglions from central area

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17
Q

(True/False): Cetaceans can see colors the way humans see color.

A

FALSE; Cetaceans see no color- only one kind of cone receptor

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18
Q

Do cetaceans have more rods or cones?

A

more rods for motion, allows them to be sensitive moving stimuli

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19
Q

The cetacean visual system has ______ ______, resulting in very little binocular vision and little depth perception

A

complete crossover

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20
Q

What is the superior colliculus for? Who has a bigger superior colliculus, humans or cetaceans?

A

visual motion; Cetaceans

21
Q

Describe the basic auditory pathway in cetaceans.

A

cochlea -> cochlear nucleus -> superior olivary (where sounds from both ears combine) ->inferior colliculus (how sounds moving) -> A1 (auditory cortex)

22
Q

Where do cetaceans have the greatest tactile sensitivity?

A

face (esp eyes, lower jaw), blowhole, genital area

23
Q

What is unique about the specialized tacto-acoustic cortex in cetaceans?

A

sound and tough converge together in this cortex so that there is a response to touch and sound; adjacent to A1 => early processing, touch and sound merged

24
Q

Vestibular tracts in cetaceans are ____ ____ compared to other mammals

A

much reduced

25
Q

What does the vestibular system allow for cetaceans?

A

enable frequent, rapid, body rotations; grace, balance handled by other systems

26
Q

Explain the ability to smell for odontocetes.

A

No smell in odontocetes = no olfactory bulb in odontocetes (severely reduced in mysticetes)

27
Q

Can cetaceans taste?

A

have taste receptors and tracts but minimal

28
Q

What is different about the limbic system in cetaceans in comparison to primates?

A

overall well developed, but with certain structures enlarged, others reduced

29
Q

What is unique about the hippocampus in cetaceans?

A

much reduced, yet have excellent memory

30
Q

The amygdala in cetaceans is ______ and heavily connected with the ______ system

A

enlarged; Auditory system

31
Q

Do cetaceans show the presence of the Theory of Mind?

A

presume, but not proven due to large amygdala; cetaceans known to live “rich emotional life” run by feelings

32
Q

What is unique about the cortex of cetaceans?

A

most convoluted surface of any mammal although cortex layer is thinner than primates

-1/3 more surface area than humans, fewer neurons, more glial cells

33
Q

What is unique about the cytoarchitecture (cell structure/configuration) in cetaceans from other mammals?

A
  • No obvious granularity in Layer IV (normally the receiving layer from Thalamus)
  • less columnar differentaiation
34
Q

The division of the occipital and parietal lobe in cetaceans is ____ ______

A

not present

35
Q

What is the S-A area in cetacean brains?

A

specialized frontal area, adjacent to S1, for processing “Tacto-Acoustic” info

36
Q

What parts of the brain do cetaceans have that allow for “higher” processing?

A
  • sulcus after sulcus in S-A and V1 area
  • unmapped Association Cortex
  • extra lobe that does not correspond to any in human/primate brain
37
Q

The Prefrontal cortex in cetaceans, including frontal pole is ______ than in humans

A

smaller

38
Q

What cetaceans have Von Economo Neurons?

A

Bottle nose dolphins, belugas, sperm whales, orcas and humpback whales for mysticetes

39
Q

Where are Von Economo Neurons found in cetaceans?

A

ACC and FI (like us); also in frontal pole (nlike us)

40
Q

(True/False): Cetacean brain is symmetrical.

A

FALSE; right hemisphere larger

41
Q

What size is the corpus callosum? What does this suggest about sleep patterns?

A

smallest corpus callosum among mammals, suggests minimal communication between 2 hemispheres, allows them to sleep with one half of brain “on” and “off”

42
Q

(True/False): Cetaceans undergo REM sleep in their final stage, stage 3, of sleep

A

FALSE; Cetaceans undergo NO REM sleep

43
Q

What stage of cetacean sleep can we only detect one hemisphere at a time?

A

3

44
Q

Why do cetaceans have to sleep with one hemisphere “on” at all times?

A

the other non asleep hemisphere must stay awake enough to breath

45
Q

Do cetaceans have mirror neurons? How does Chris feel about it and what would she bet to prove it?

A

not proven; Chris believes they do and would bet her firstborn

46
Q

Dolphins preferentially use _____ eye , which gets from information from the _____ brain to look at strangers

A

left eye, right brain

47
Q

Humans are lateralized to ______ hemisphere for speech and handedness

A

LEFT

48
Q

What is unique about the cetacean brain compared to primates?

A

faces down, strange layout that is very different than primates, faces opposite way of primates

COGS 143 (17 decks)

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