Language and the Brain: Key Concepts

Neuroanatomy of Language

Language Lateralization
- 90% of right-handed individuals have language functions centralized in the left hemisphere.
- 70% of left-handed and ambidextrous individuals also have language centralized in the left hemisphere.
Main Language Areas
- Broca's Area:
  - Located in the frontal lobe (usually left).
  - Responsible for language expression.
  - Damage leads to Broca's aphasia (non-fluent aphasia), characterized by difficulty producing speech ("broken speech").
- Wernicke's Area:
  - Located in the temporal lobe.
  - Responsible for language comprehension.
  - Damage leads to Wernicke's aphasia (fluent aphasia), characterized by nonsensical speech and difficulty understanding language.

Global Aphasia:
- Occurs when both Broca's and Wernicke's areas are affected, impacting all language functions.
Conduction Aphasia:
- Caused by damage to the arcuate fasciculus, the nerve fibers connecting Broca's and Wernicke's areas.
- Leads to difficulty repeating words despite understanding them.
Other language disorders include:
- Agraphia: Inability to write.
- Anomia: Inability to name objects.

Neural Plasticity/Synaptic Plasticity:
- Brain's ability to rewire and adapt after damage.
- Allows other parts of the brain to take over functions of damaged areas, helping recovery in conditions like post-stroke speech impairment.

Corpus Callosum:
- Nerve fibers connecting the two hemispheres.
- Severing it treats seizures but disrupts interhemispheric communication, leading to split-brain conditions.
Contralateral Organization:
- Left visual field processed by the right hemisphere and vice versa.
- Split-brain patients can't verbally identify objects seen in the left visual field but can handle them with the left hand.

Understanding of brain organization and localization of language functions aids in treatment and rehabilitation strategies for language impairments.