Language

Language is Lateralized, Localized

Left frontal and temporal association cortices

Role of the Right Hemisphere

Prosody – “coloring” of speech

Includes the rhythm, timing, emphasis, volume, tonal (pitch) variations of verbal speech

Conveys emotion and grammatical emphasis

Sites where electrical stimulation interferes with speech production (W. Penfield, 1950’s)

Positron Emission Tomography (PET)

Aphasia

A disorder that impairs a person's ability to process language but does not affect intelligence.

Most common cause is stroke (about 25-40% of stroke survivors acquire aphasia), but also caused by head injury, brain tumor or other neurological causes.

Affects about one million Americans, and is more common than Parkinson's Disease, cerebral palsy or muscular dystrophy. More than 100,000 Americans acquire the disorder each year.

Broca’s Area

Left frontal lobe Broca’s aphasia

Motor, “expressive” aphasia

Disruption of language production (finding/expressing the right words) and organization (grammar, syntax)

Problems apparent with written, spoken, “signed” language

Patients cannot produce speech, but CAN understand speech

Patients are acutely aware of their problem

Sarah Scott

Wernicke’s Area

Rear left temporal lobe

Wernicke’s aphasia

Sensory/receptive aphasia

Language produced, sounds normal, but much of it makes no sense

Many patients seem to be completely unaware of their problem

Byron Anderson

§   Conduction Aphasia:  damage to fibers (arcuate fasciculus) linking Wernicke’s and Broca’s areas .

§   Patients have problems producing appropriate responses to language, even though the language is understood. 

§   Characterized by poor speech repetition. 

§   Patients seem to lose their train of thought – due to lack of communication between Wernicke’s area (sound / meaning) and Broca’s area (motor commands)

§   Conduction aphasia

Split-Brain Subjects