Language and Lateralization Flashcards
(39 cards)
What function is the most understood to be lateralized in the human brain?
Language skills are lateralized, more so than any other brain process
Broca’s Area
Key in language processing
Appears to be involved in speech production
Broca’s aphasia = Damage causing difficulty in speech production
Wernicke’s Area
Important for language comprehension
Damage causes difficulty understanding language
e.g. vocalizations can be made, but grammar, syntax, and language use suffer greatly
Broca and Wernicke’s areas are both on the…
Left side
For right-handed individuals at least
No Aphasics…
Have damage restricted to JUST Broca’s or Wernicke’s area
Aphasics almost always have damage to…
Subcortical white matter
Which types of lesions are most likely to produce expressive symptoms?
Large anterior legions
Global aphasia is usually related to…
Massive lesions of across several regions
Aphasics sometimes have damage not enroaching innto broca/wernickes area. For example…
Maybe the Broca’s area is fine, there is damage in the white matter tracts
can no longer send information to next region causing speech production issues
Damasio’s PET study of naming
- Images of famous faces, animals, and tools
- Activity while judging image orientation subtracted from activity while naming
- Left temporal areas activated by naming, beyond wernickes area
Electrical stimulation to cortex on language ability - Study
- Left hemisphere of a 37-yr old epileptic
- Number areas on brain where stimulation applied
- Same study completed on monkey’s, same areas reported
- Many sites where stimulation produces either complete arrest of speech or disrupted/not blocked completely
Is language learned or innate?
Both!
- Some appear to be innate, some learned through experience
- Same for many processes
- Some inheritability/differences in ability to learn language
FOXP2
- Specific gene, shown to be relevant to language development
- Neanderthals shared this gene, monkeys do nott
FOXP2 and Mice
Mice with FOXP2 gene mutations do not evoke communicative ultrasonic vocalizations
FOXP2 and Birds
When FOXP2 expression is blocked, young male birds fail to learn and recite bird song
Suggestions of innate language ability
- Many animals have some rudimentary communicative skills
- Not the same as language (which requires a grammatical code)
- Although, we are the ones who have defined language as requiring grammatical code, so it is by our definition that other organisms versions of communication do not meet threshold for language
Song areas in birds
- Very similar to the neural circuits for language area in humans
- Similarities maintained in its rudimentary form
The learned nature of language
we aren’t just born with the ability to converse
Takes time for us to develop language skills, most certainly happens through exposure
Critical period
Period in development when exposure or practice must occur for skills to develop
Example of a critical period
Visual processing
Plasticity of brain will reconnect a baby’s neurons from a blind eye, this the eye must be recovered quickly or normal sight will never be regained
Sensitive period
A period in development when exposure or practice will most facilitate the development of skills
Example of sensitive period
Social behaviour
An individual who experiences extreme stress as a child may show social deficits/abnormalities, these abnormalities can be overcome (sort of, sometimes)
Sensitive period of language
- Appear to be formed in early childhood to late adolescence (earlier and earlier)
- Adults who try to learn a language have a much harder time
- Most interestingly, they appear to learn language differently too!
Comparison of adult/Child Bilinguilism
- Specific area activating for native language 1&2, many overlap
- Adult has much less overlap
- Region in anterior temporal cortex appears to be active for language
- Broca’s area, inferior temporal cortex
