Chapter 19: Language and Lateralization Flashcards
lateralization
one hemisphere being more specialized in one domain compared to other hemisphere
what is the most well-known lateralization of function?
langauge
what do split-brain individuals prove?
the two hemispheres are not identical in terms of language functioning and they are lateralized
what type of people were tested for split-brain experiments?
those with corpus callosum cut out
what was the split-brain experiment?
words or pictures projected to the left visual field activate the right visual cortex
control participant of split-brain experiment
at the optic chiasm, half of the fibers from each eye cross over, so the left hemisphere sees the right visual field, vice versa
why can the split-brain participant not verbally respond to a stimuli from left visual field?
the stimuli can reach the right-hemisphere via the subcortical visual pathways but the severed corpus callosum prevents the right-hemisphere visual areas from communicating with the language areas of the left hemisphere
why can the split-brain participant verbally respond to stimuli appearing in the right visual field?
interhemispheric transfer is not require
if you ask the split brain participant to pick out something with their left hand and ask why they picked that picture, what happens?
they will confabulate (make something up) because the left hemisphere is trying to explain the behavior after the fact
can the right hemisphere recognize the object the participant picked up with their left hand?
yes and they can investigate by having left hand feel for correct matching object
which hemisphere is stronger in language?
left
right hemisphere
can recognize simple words and participates in the emotional content of verbal material
- specialized for spatial information, facial perception and attention
callosal agenesis
individuals lacking a corpus callosum but are not present as split-brain individuals
what occurs in callosal agenesis individuals?
the developing nervous system compensates for the loss of the main connections between the hemispheres, perhaps through other inter-hemispheric connections
dichotic presentation
present two sounds to the two areas at the same time
through dichotic presentation, which ear has an advantage?
right ear
why does the right ear have an advantage?
the right ear connects with the left auditory cortex better and since the left hemisphere processes language, anything presented to the right ear has an advantage
what hemisphere processes sound?
the sound reaches both sides but is processed by the opposite hemisphere
example: sound from left ear is processed by right hemisphere
how is verbal information presented to the left ear processed?
by the right auditory cortex and transmitted to speech systems in the left hemisphere and then participant repeats the word
how is verbal information presented to the right ear processed?
by the left auditory cortex and then passed directly to speech systems within the same hemisphere
what happens when conflicting information goes to both ears?
the information to the right ear reaches left hemisphere’s speech system first and the subject only repeats right-ear information
tachistoscope test
presents images in one visual field but too briefly for the eyes to move and center the image on the fovea
what is the result of the tachistoscope test?
left visual field information only processed by right visual cortex and vice-versa
what does the tachistoscope test confirm?
left hemisphere is better at recognizing verbal stimuli and right hemisphere is better with faces or shapes (nonverbal stimuli)
when does asymmetric gene expression begin?
as early as 12-14 weeks after gestation
when do primates show greater left hemisphere activation?
when listening to other primates
what do non-primates and non-mammals show preference for?
limbs on one side over the other
planum temporale
region in temporal lobes
what hemisphere is the planum temporale bigger in?
left hemisphere
what type of individual shows a more distinct difference in planum temporale?
musicians
what hemisphere plays a larger role in people who are right handed?
left hemisphere
wada test
allow the study of each hemisphere in isolation
what is the wada test used to understand?
facial recognition
what is the process of the wada test?
anesthetic is injected into the carotid artery through a catheter and temporarily shuts down the cerebral hemisphere on the same side, thereby revealing the functions performed by that hemisphere
if the right hemisphere is dominant for language, who does it occur in?
left handed people
what is the right hemisphere better for?
better at processing spatial stimuli including shapes, faces, rotation of objects, etc
prosopagnosia
face blindness
can people with prosopagnosia recognize their own face?
no
what hemisphere is damaged in those with prosopagnosia?
right hemisphere because there are impairments in facial recognition
what is prosopagnosia associated with?
agnosia
agnosia
inability to identify items, frequently individuals with large categories
fusiform system
may contain subregions important for identifying individuals with large categories in general (faces or cars)
complete prosopagnosia
caused by bilateral damage
complete prosopagnosia can be ____
acquired or congenital
are communication and language are not the same thing?
no, but language is a kind of communication
can apes and chimps learn language?
no, they cannot even within a training environment
birdsong
used as an analog to human language
- males produce a song as part of social and reproductive behavior
3 steps of vocal behavior of animals
- exposure to song via tutor (father) becomes stored model
- trial and error: male practices song to match model
- fixing or crystalization of song into permanent form
lesions of direct pathway ___________
disrupt song performance at any time
lesions of indirect pathways _____
disrupt song acquistion
lesions in adulthood _____
do not disrupt performance`
phonemes
basic speech sounds that are blended together into morphemes
morphemes
basic units of “meaning”
semantics
words with meaning, could be combination of morphemes
syntax
words are strung together in a meaningful way following grammatical rules
what is our speech affected by?
pragmatics and prosody
pragmatics
the context in which a speech sound is uttered
prosody
emotional tone and emphasis that we add to the things we say
human brain is adapted for ____
language
when do humans learn language the best?
early in life
how was language evolved with?
hand and face gestures
people born blind use ____
hand gestures
deaf people who sign use ______
same parts of brain as spoken language
deaf children without access to sign language, ______
develop their own
anterior frontal region of the left hemisphere
Broca’s area
area of temporoparietal cortex is called ____
Wernicke’s area
lesions in the Broca’s area interfere with ______
speech production
injury to Wernicke’s area interferes with _____
language comprehension
injury to the supramarginal gyrus interferes with _____
repetition of heard speech
what hemisphere is the Broca’s area, Wernicke’s area, and supramarginal gyrus in?
left hemisphere
aphasia
language impairment
what is aphasia accompianed with?
agraphia
agraphia
inability to write
alexia
reading impairment
non-fluent aphasia (Broca’s aphasia)
language impairment characterized by speech production but not with language comprehension
where brain structure is damaged with non-fluent aphasia?
broca’s area
what are some characteristics of non-fluent aphasia?
have difficulty producing speech, talking only in a labored and hesitant manner but automatic is preserved
fluent aphasia (Wernicke’s aphasia)
language impairment characterized by fluent, meaningless speech and little language comprehension
what brain structure is damaged with fluent aphasia?
Wernicke’s area
what do people with fluent aphasia often have?
anomia
anomia
difficulty naming objects/people
characteristics of fluent aphasia
difficulty repeating words and understanding language but can interpret facial experessions
global aphasia
total loss of ability to understand language or to speak, read, or write
what does global aphasia result from?
large left hemisphere lesions
Wernicke’Geschwind Model (connectionist model of aphasia)
argues that language deficits due to brain damage result from disconnection between brain regions that form a language network
what is the problem with the Wernicke-Geschwind Model?
does not work well for explaining language
differences between Broca’s area and Wernicke’s are ____
not clear
what do images and electrophysiological recording studies show?
large variations in regions responsible for different aspects of language
when speaking a heard word, where is the information about the sound analyzed?
by the primary auditory cortex and transmitted to Wernicke’s area
when speaking a heard word, what does Wernicke’s analyze?
the sound information to determine the word that was said
when speaking a heard word, where does the connectionist model say it is transmitted through?
arcuate fasciculus
how does broca’s area play a part in speaking a heard word?
it forms a motor plan to repeat the word and sends that information to motor cortex
when speaking a heard word, what does the motor cortex do?
it implements the plan manipulating the larynx and related structures to say the word
what do lesions of the arcuate fasciculus disrupt?
the transfer from Wernicke’s area to Broca’s area, so the person has difficulty repeating spoke words (conduction aphasia) but can still retain comprehension of spoken language because they have an intact Wernicke’s area and can speak spontaneously because of intact Broca’s area
when speaking a written word, what brain structure analyzes the information and where does it get transmitted to?
visual cortex analyzes the image and transmits information about the image to the angular gyrus
when speaking a written word, what does the angular gyrus do?
decodes the image information to recognize the word and associate this visual form with the spoken form in Wernicke’s area
when speaking a written word, how is the information about the word transmitted and where does it get transmitted to?
via the arcuate fasciculus to the Broca’s area
when speaking a written word, what does the Broca’s area do?
formulates a motor plan to say the appropriate word and transmits the plan to motor cortex for implementation
when speaking a written word, what does the motor cortex do?
implements the plan, manipulating the larynx and related structures to say the word
a lesion of the angular gyrus disrupts ______
the flow of information from visual cortex, so the person has difficulty saying words they have seen but not words they have heard
arcuate fasciculus
white matter tract that connects Wernicke’s area to Broca’s area
damage to arcuate fasciculus can produce ______
conduction aphasia
conduction aphasia
impairment in the repetition of words and sentences but you still have fluent speech and comprehension
motor theory of language
theory proposing the left hemisphere language zones are motor control systems that are concerned with precise production and perception of complex movements that go into speech
anterior region
programs simple phonemes of speech (production)
posterior region
string sounds into long sequences of movement (reception)
speech sounds are just ______
auditory representations of complex facial movements and gestures, but we perceive those sounds with the same brain regions we use to make the movements
when bilingual individuals had their brain sites stimulated, what happens
different subregions, in one region affecting speech, interfere with either one language or the other
- they were not both affected in the same subregion
TMS
can be used to identify regions involved in speech
what does speech perception activate?
specific regions that TMS shows to be involved with speech production
what does speech production involve?
hand areas of motor cortex
what does TMS stimulation affect when applied to anterior regions of Broca’s area?
semantic processing (meaning)
what does TMS stimulation affect when applied to posterior regions of Broca’s area?
phonological processing (sound patterns)
PET scans
during different language tasks reveals overlapping yet distinct systems involved in language
passive viewing of words activates ______
posterior area within the left hemisphere
passive hearing of word activates ________
temporal lobes
repeating words orally activates _______
motor cortex of both sides, supplementary motor cortex, and a portion of cerebellum and insular cortex
what brain structure has little activity when repeating words?
broca’s area
when partcipants are asked to generate a verb to the supplied noun, what happens?
language related regions in left hemisphere, including Broca’s area are activated
silbo gomero
whistling language used in the Canary Islands
what does the fMRI reveal about the Silbo language?
it is processed in the same regions as spoken language in silbo users
what happens in non-silbo users?
the whistling is processed in other regions because they do recognize it as a language
sign language
uses the same parts of the brain as verbal language
williams syndrome
deletion of about 28 genes and involves increased fluency and mild cognitive disability
stuttering
disordered articulated of speech sounds and involuntary repetition of words and phrases
is stuttering genetic?
it can be partially heritable
our brain evolved to support _____
language
reading is a ______
recent development
dyslexia
difficulty reading but not related to intelligence
acquired dyslexia
typically occurs due to lesions of some kind
developmental dyslexia
brain abnormalities present from birth
how many % of children does developmental dyslexia occur in?
5%
what kinds of children is developmental dyslexia common in?
boys and left handed people
deep dyslexia
type of acquired dyslexia in which the person reads a word as another word with a similar meaning
characteristics of deep dyslexia
have trouble reading nonsense words, often grasp whole words without letter details
surface dyslexia
type of acquired dyslexia in which the person seems to attend only the fine details of readig
characteristics of surface dyslexia
can read nonsense words because they know letter to sound rules
- but can have trouble recognizing words when letter-to-sound rules are irregular
- does not occur in perfectly phonetic languages
what appears in people with dyslexia?
microscopic anomalies called ectopias, dysplasia, and micropolygria in their left hemisphere
developmental dyslexia involves deficits in _____
phonological processing and recognizing phonemes
what brain structure activation is affected in individuals with dyslexia?
they have smaller activation of posterior regions (Wernicke’s area and angular gyrus) and increased activation of anterior regions
what dysfunction is associated with alphabetical letters?
left temporoparietal cortex
what dysfunction is associated with logographic symbols?
left medial frontal cortex
can the brain recover from injuries producing aphasia?
yes, because the brain is shapable based on experience
can children who receive left hemispherectomies recover?
yes, they can still develop language function and overcome some paralysis of opposite side of body
