Chapter 13 Flashcards
left and right hemisphere connect to..
..each hemisphere connects so muscles and skin receptors on their contralateral body side
-exceptions: trunk and facial muscles (controlled by both), taste and smell are uncrossed
lateralization
each hemispheres has a different function
connection of the two hemispheres through …
- the corpus callous ( set of axons)
- anterior commissure and hippocampal commissure
visual connection of hemispheres
- both eyes are connected to both hemispheres
- information from the right visual field falls into the left half of each retina which connects to the left hemisphere - optic chiasm (cross) axons from the left half of the right retina got o the left hemisphere (and vice versa)
split- brain operations
- surgically damage of corpus callosum in severe epilepsy
- either remove the focus point within corpus callosum where seizures begin or cut out the whole corpus callous
consequences of damaged corpus callosum
- split brain people remain fairly normal
- but : struggle on unfamiliar tasks when both hands are needed
- can use both hands independently in ways other people cannot
-> BUT hemispheres still do not act in complete isolation!
=> left hemisphere is responsible for speech production,
whilst both hemispheres can comprehend
- > split brain patients can understand with both hemispheres but only information shown to the left hemisphere can be vocalized!
-as time passes after the surgery, brain learns to use smaller connections between hemispheres to make up for the lost corpus callosum
the interpreter
tendency of the left hemisphere to make up explanations for what the right hemisphere did
comparison left and right hemisphere
- right hemisphere (holistic): better than the left at comprehending spatial relationships
- > focuses more on overall patterns whereas the left focuses on detail
- > right hemisphere sees the ‘bigger picture’, relates what’s been heard to the overall context
- is more responsive to emotional processing -> more fine tuned to gestures, tone of voice, sarcasm, happiness or sadness of others
- left hemisphere (analytical): responsible for processing language
- > but without right hemisphere, left hemispheres understanding would be very literal
plantum temporale (temporal cortex) is larger in 1……..hemisphere from when we are born -> resulting in 2…. handedness
1- left , 2- right
Maturation of the Corpus Callosum
- gradually grows and thickens as some axons are myelinated in childhood/adolescence
- matures through discarding many axons
- > overproduction in early development and two neurons connected each other to corpus callosum. These two neurons need to have corresponding functions
- connections that integrate info from both hemispheres develops between 3-5 years
- > before, some behaviors of children resemble adult split brain behaviors
human language has..
- productivity = ability to improvise new combinations to represent new ideas
- this makes human language distinct
teaching language to chimpanzees
- attempts failed because humans vocalize while breathing out, chimpanzees vocalize whilst breathing in
- when taught to communicate in symbols, it remained unclear whether they understood the meaning
- > their use was short in productivity
- > only used symbols to request and not to describe
- However, they were able to differentiate between who, where, and what questions
teaching language to bonobos
- > Bonobos are similar to humans in many aspects (sex face to face, outside of fertile periods, build bonds, male contributes to childcare)
- > Kanzi could understand, follow instructions, describe, but not produce
- > learned when he was young, learned by observation since his mom was taught
teaching language to non primates (parrot)
- african gray parrot could speak without food rewards
- > has implications for how to teach people who do not learn language well
- our language has evolved from other species
- > we cannot decide whether chimpanzees or parrots have language unless we define it more clearly
possible explanation for development of language in humans
- development of the phonological loop might have facilitated language
- > stronger connections between auditory cortex and pre-frontal cortex => better auditory memory
- language developed out of gestures
- > especially mouth gestures in monkeys
evolutionary theory on language
- humans have evolved bigger brains and language is a by-product of this
- criticism: whales have even bigger brains but no language
- > not everyone with a full sized brain and normal intelligence has normal language ( williams syndrome)
williams syndrome
people can speak normally but have low intelligence
language acquisition device (LAD) ( chomsky)
- language as a built in mechanism
- > kids learn so quickly as if they were biologically prepared
- > FOXP2 gene regulates proteins that promote synapse formation in cerebral cortex
- > this has an effects of jaw- and throat structures related to speaking
Bilingualism/ sensitive periods for language acquisation
- people who learned a second language before 12 have native-like proficiency
- bilinguals from infancy show bilateral activity during speech of both languages
- > people who learn after age 6 show only left hemisphere activation for both languages
- bilinguals have better attention control
- a child who learns no language within the critical period will not become proficient at any language later in life
aphasia
language impairment
- brain damage in general can be a way to study specializations for language by correlating damage brain region to deficits in verbal behavior