Flashcards in Cetaceans: Brains Deck (48)
Why does absolute brain size matter?
more matter = more connections
What is Encephalization Quotient (EQ)?
ratio of actual brain mass to expected brain mass of comparison animal, corrected for body size
What is special about the cerebellum for Tursiops?
bottlenose dolphins have largest relative size of any cerebellum of any mammal
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
Unlike primates who are altricial, cetaceans are ______ at birth
precocial (well developed)
Dolphins have ____ month gestation
Dolphin brain at birth is _____% of the adult brain
Human brain at birth is _____% of the adult brain
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
Cetacean auditory nerve has _____ times the fibers to humans
What is unique about the auditory system for cetaceans?
main source of info on shape, size, content, distance of stimuli
Cetaceans have what in their auditory nerve to increase transmission speed?
huge, myelinated fibers
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
Explain the dual processing system
brain stem = giant, broadband, brief, fast changing inputs
cortex = layers, intepreting sound => "Language"/higher cognitive processing
What is similar and different about the auditory system in humans and dolphins?
dolphins have same process but the proportions at each stage different
(True/False): Cetaceans have small amounts of fovea
FALSE; Cetaceans have NO fovea
BUT have dense, giant, myelinated ganglions from central area
(True/False): Cetaceans can see colors the way humans see color.
FALSE; Cetaceans see no color- only one kind of cone receptor
Do cetaceans have more rods or cones?
more rods for motion, allows them to be sensitive moving stimuli
The cetacean visual system has ______ ______, resulting in very little binocular vision and little depth perception
What is the superior colliculus for? Who has a bigger superior colliculus, humans or cetaceans?
visual motion; Cetaceans
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)
Where do cetaceans have the greatest tactile sensitivity?
face (esp eyes, lower jaw), blowhole, genital area
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
Vestibular tracts in cetaceans are ____ ____ compared to other mammals
What does the vestibular system allow for cetaceans?
enable frequent, rapid, body rotations; grace, balance handled by other systems
Explain the ability to smell for odontocetes.
No smell in odontocetes = no olfactory bulb in odontocetes (severely reduced in mysticetes)
Can cetaceans taste?
have taste receptors and tracts but minimal
What is different about the limbic system in cetaceans in comparison to primates?
overall well developed, but with certain structures enlarged, others reduced
What is unique about the hippocampus in cetaceans?
much reduced, yet have excellent memory