Tests of Cerebral lateralization

• Lesions

• Sodium amytal test

• Dichotic listening test

• Functional brain imaging

• Split brain

Theories of Cerebral Asymmetry

• Analytic-Synthetic theory

• Motor theory

• Linguistic theory

Broca’s Aphasia

• Impaired language production

• Overall language comprehension was not a problem UNLESS the meaning depended on prepositions, and other grammatical devices

• Some production difficulties– “To be or not to be”– Two bee oar knot two bee

Wernicke’s Aphasia

• Difficulties with nouns and verbs

• Trouble with language comprehension

• “Word Salad”

Summary

• Broca’s aphasia– More trouble with production of language– Problems with prepositions, conjuctions

and pronouns

• Wernicke’s aphasia– More trouble with comprehension– Problems remembering and knowing

nouns and verbs.

Conduction Aphasia

• Arcuate fasciculus

• Conveys information about the sounds of words, but not their meaning

• Poor repetition of unfamiliar words

Wernicke-Geschwind

• Conversation– Auditory signal to primary cortex– Primary cortex to Wernicke’s area– Wernicke’s area to Broca’s area (via

arcuate fasiculus)– Broca’s area to primary motor cortex– Primary motor cortex to vocalizaton

Wernicke-Geschwind

• Reading aloud– Primary visual cortex to left angular gyrus– Left angular gyrus to Wernicke’s area– Wernicke’s area to Broca’s area (via

arcuate fasiculus)– Broca’s area to primary motor cortex– Primary motor cortex to vocalizaton

Dyslexia

• Developmental dyslexia– Planum temporale

• Acquired dyslexia– Lexical procedure and phonetic procedure– Surface dyslexia– Deep dyslexia– Word-form spelling– Direct– Alexia