Language Disorders

Signer Aphasia

• Young man, both spoken and sign language:
• Accident and damage to brain
• Both spoken and sign languages are affected
• Deaf-mute person, sign language:
• Stroke and damage to left-side of the brain
• Impairment in sign language
• 3 deaf signers:
• Different damages to the brain with different impairments to grammar and word production

Spoken and Sign Languages

• Neural mechanisms are similar
• fMRI studies show similar activations for both hearing and deaf
• But in signers, homologous activation on the right hemisphere is unanswered yet

Dyslexia

• Problem in learning to read
• Common in boys and left-handed
• High IQ, so related with language only
• Postmortem observation revealed anomalies in the arrangement of cortical cells
• Micropolygyria: excessive cortical folding
• Ectopias: nests of extra cells in unusual location
• Might have occurred in mid-gestation, during cell migration period

Acquired Dyslexia = Alexia

• Disorder in adulthood as a result of disease or injury
• Deep dyslexia (pays attn. to wholes):
• “cow” -> “horse”, cannot read abstract words
• Fails to see small differences (do not read each letter)
• Problems with nonsense words
• Surface dyslexia (pays attn. to details):
• Nonsense words are fine
• Suggests 2 different systems:
• One focused on the meanings of whole words
• The other on the sounds of words

Electrical Stimulation

• Penfield and Roberts (1959): During epilepsy surgery under local anesthesia to locate cortical language areas, stimulation of:
• Large anterior zone:
• stops speech
• Both anterior and posterior temporoparietal cortex:
• misnaming, impaired imitation of words
• Broca’s area:
• unable comprehend auditory and visual semantic material,
• inability to follow oral commands, point to objects, and understand written questions