Cetaceans: Brains Flashcards Preview

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Flashcards in Cetaceans: Brains Deck (48):
1

Why does absolute brain size matter?

more matter = more connections

2

What is Encephalization Quotient (EQ)?

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

3

What is special about the cerebellum for Tursiops?

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

4

What does the cerebellum do for cetaceans?

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

-areas controlling face, trunk and tail = ENLARGED
*articulate vocalizations

5

Unlike primates who are altricial, cetaceans are ______ at birth

precocial (well developed)

6

Dolphins have ____ month gestation

12

7

Dolphin brain at birth is _____% of the adult brain

40

8

Human brain at birth is _____% of the adult brain

25

9

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

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

10

Cetacean auditory nerve has _____ times the fibers to humans

2.5

11

What is unique about the auditory system for cetaceans?

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

12

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

huge, myelinated fibers

13

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?

easily find where sounds are

14

Explain the dual processing system

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

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

15

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

dolphins have same process but the proportions at each stage different

16

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

FALSE; Cetaceans have NO fovea

BUT have dense, giant, myelinated ganglions from central area

17

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

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

18

Do cetaceans have more rods or cones?

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

19

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

complete crossover

20

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

visual motion; Cetaceans

21

Describe the basic auditory pathway in cetaceans.

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

22

Where do cetaceans have the greatest tactile sensitivity?

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

23

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

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

Vestibular tracts in cetaceans are ____ ____ compared to other mammals

much reduced

25

What does the vestibular system allow for cetaceans?

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

26

Explain the ability to smell for odontocetes.

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

27

Can cetaceans taste?

have taste receptors and tracts but minimal

28

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

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

29

What is unique about the hippocampus in cetaceans?

much reduced, yet have excellent memory

30

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

enlarged; Auditory system

31

Do cetaceans show the presence of the Theory of Mind?

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

32

What is unique about the cortex of cetaceans?

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

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

-No obvious granularity in Layer IV (normally the receiving layer from Thalamus)
-less columnar differentaiation

34

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

not present

35

What is the S-A area in cetacean brains?

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

36

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

-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

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

smaller

38

What cetaceans have Von Economo Neurons?

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

39

Where are Von Economo Neurons found in cetaceans?

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

40

(True/False): Cetacean brain is symmetrical.

FALSE; right hemisphere larger

41

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

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

42

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

FALSE; Cetaceans undergo NO REM sleep

43

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

3

44

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

the other non asleep hemisphere must stay awake enough to breath

45

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

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

46

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

left eye, right brain

47

Humans are lateralized to ______ hemisphere for speech and handedness

LEFT

48

What is unique about the cetacean brain compared to primates?

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