Download Topic 21

Biology 463 - Neurobiology
Topic 21
Language
Lange
Language
• Language
– System by which sounds, symbols, and gestures used for communication
– Process
• Language comes into brain through visual and auditory systems
• Motor system: Produces speech, writing
• Processing between sensory and motor systems; Essence of language
The role of the CNS in development of language:
• The brain is the coordinating center of all linguistic activity
• it controls both the production of linguistic cognition and of meaning and the
mechanics of speech production
• our knowledge of the neurological bases for language is quite limited, though it has
advanced considerably with the use of modern imaging techniques
• discipline of linguistics dedicated to studying the neurological aspects of language
is called neurolinguistics
Carl Wernicke
Paul Brocca
Neuroscientists in the 19th century discovered two areas in the brain that are crucially
implicated in language processing:
• the first area is Wernicke's area, which is located in the posterior section of the superior
temporal gyrus in the dominant cerebral hemisphere
• people with a lesion in this area of the brain develop receptive aphasia, a condition in
which there is a major impairment of language comprehension, while speech retains a
natural-sounding rhythm and a relatively normal sentence structure.
• the second area is Broca's area, located in the posterior inferior frontal gyrus of the
dominant hemisphere.
• people with a lesion to this area develop expressive aphasia, meaning that they know
what they want to say, they just cannot get it out.
Language Areas of the
brain:
• Angular Gyrus is represented in orange
• Supramarginal Gyrus is represented in
yellow
• Broca's area is represented in blue
In addition to the original two areas,
it has now been shown that there are
five primary areas related to language
in the human brain.
• Wernicke's area is represented in
green
• Primary Auditory Cortex is represented
in pink.
The Wada Test, named after Japanese Canadian neurologist Juhn Atsushi Wada is used
to establish cerebral language and memory representation of each hemisphere.
• test is conducted while the patient is
awake
• a barbiturate (usually sodium
amobarbital) is introduced into one of the
internal carotid arteries via a cannula
• the drug is injected into one hemisphere
at a time
• the effect is to shut down any language
and/or memory function in the respective
hemisphere
• the patient is engaged in a series of
language and memory related tests
Juhn Atsushi Wada
Wada Test
– Used to determine hemisphere dominant for
speech
END.