Chapter 16: Being Different From Others Flashcards
complex brains evolved at least ___ times among animals. outline the general outline of nervous system evolution
3 times. 1) no neurons 2) nerve nts: neurons distributed throguhout the body with no centralization 3) cerebral ganglia.CNS is inlarged in ganglia, some cephalization occured 3) brain and spinal cord.
The smaller the animal, the _____ its brain:body ratio (other things being equal)
HIGHER.
for their body size, ___ and ___ have the largest brains
birds and mammals
T/F: brain:body radios remain constant as brains brains increase in size. What is this trend?
FALSE. there is NEGATIVE ALLOMETRY. brain body ratios decrease in larger animals. smaller animals have higher brain body ratios. ex/ mammals have relatively large brains for their body size compared to larger reptiles.
Which animal has the highest encephalization quotient?
humans. we don’t have the largest brains, but we have the largest brains for our body size. eq= actual brain size/expected brain size
as you get to larger and larger brain, which portion gets disproportionately large?
the neocortex
T/F: humans have the highest brain to body ratio.
false. Brain-body ratios tend to decrease with increasing body size, which means that some animals with very small bodies tend to have very high brain-body ratios.
the fossil record suggests that absolute brain size in our closest ancestors increased in two relatively brief growth spurts, separated by a long period of relative stability. when were they?
1) brain growth spur when early hominids tamed fire –> allowed homo erectus to cook its food and obtain more nutrients. 2) after the evolution of homo sapiens and is most likely linked to intraspecific competition for reousrces and mates (social maneuvering required more social intelligence and thus this was favored)
in both primates and rodents, neuron numbers increases with increasing brain rate. What is the difference between these two groups?
the rate of neuron number increases significantly faster in primates than in rodents. therefore, large primate brains contain more neurons than equally large rodent brains.
of the various neocortical areas, the ____ and ___ lobes are proportionally smaller in humans than in non human primates, but the prefrontal cortex is much larger.
of the various neocortical areas, the TEMPORAL and OCCIPITAL lobes are proportionally smaller in humans than in non human primates, but the prefrontal cortex is much larger.
language is most affected by ____ sided brain lesions, espeically in the inferior ___ ____,
language is most affected by LEFT sided brain lesions, especially in the inferior prefrontal cortex. aka BROCAS AREA.
where is wernickes area? What is it’s function?
posterior portion of the superior TEMPORAL LOBE. impairs language comprehension without impairing speech. people with damaging this area can speak fluently (unlike brocas aphasia)
conduction aphasia
lesions in the inferior parietal lobe that resuls in word repetition and deficits in object naming
transcortical aphasia
lesions in the prefrontal cortex that results in language deficits.
even though the broca and wernickes area are on the lefts side, how does the right side of the brain affect langauge?
it involved in the prosodic aspects of language, including rhythym, stress, and intonation. people with damage to the right side of the brain tend to speak in a monotone fashion.
T/F deaf people exhibit the same brain activity as people with spoken language
true. they show similar amounts of activation in Broca’s area and the auditory cortex, but in deaf people, the auditory cortex also lights up when they read sign language.
language-related circuitry can be divided into ___ and ___ streams.
dorsal and ventral
the dorsal langugage related circuit passes through the ___ ___ lobe and is involved in the ____ of speech. the ventral language related circuit passes toward the ___ ___ lobe and is involved in speech _____.
the dorsal langugage related circuit passes through the INFERIOR PARIETAL lobe and is involved in the PRODUCTION of speech. the ventral language related circuit passes toward the ANTERIOR TEMPORAL lobe and is involved in speech COMPREHENSION.
in terms of the dorsal/ventral model of speech, when is speech processesing bilateral? When is it left hemisphere dominant?
only the late stages of speech processing are left hemishere dominant, the others are bilateral.
what gene and its mutation MAY be correlated with language deficits
FOXP2 gene. FOXP2 portions were substituted in mammals that led up to humans. also, families with a mutated FOXP2 gene can’t talk and have smaller brocas areas. but they also have other problems too, so its tough to say if FOXP2 is alone responsible for language and language deficits.
the Y chromosome contains the ___ gene, which causes gonadal precursor tissue to develop into testes rather than ovaries
SRY gene.
how does testosterone promote brain masculization
during embryonic development and shortly after birth, a male’s testes produce a surge of testosterone.
- this testosterone binds to androgen receptors in the external genitalia, which in response, enlarge the embryonic phallus into a penis
- in the brain, all the testosterone produced is converted to estradiol via the enzyme aromatase.
- estradiol binds to estrogen receptors and causes the cell expressing those receptors to develop in the male-typical direction.
during early postnatal development, females express very little estrogen, and whatever estrogen they do express is sequestered by ___ ____, which does not cross the BBB
alpha fetoprotein
explain how the gynandromorph finch’s sex differences result from both genomic and circulating sex hormone effects
1) genomic effects: cells on right side of the gynandromorph finch contained the male mix of sex chromosomes, where as most of the cells on the left side contained the female sex chromosomes.
- left/right differences in the plumage of this finch were most likely caused by genes that are locted on only one of the sex chromosomes.
2) sex hormone effets: the song system HVC (telencephalic cell group) on the right side is larger on the left, because the “male” side is more likely to sing. but, the song system on the left side is also larger than most “full female” finches, indicating that the “female side” of this gynandromorph brain has been affected by the testosterone (and then converted estradiol) that was circulating from the birds single testis.
onuf’s nucleus
the spinal motor neurons that innervate muscles at the base of the penis or nearby muscles.
which sex has a larger onuf’s nucleus
males have larger onug’s nucleus. this structure is englarged in the presence of testosterone in newborns, which is higher in males