2007PSY BioPsych Week 11

2007PSY BioPsych Week 11

1. Aitchison’s Ten Criteria for Language

2. Origins of Language

   • -No human culture on earth exists without language -Possible existence of independent “language module” in the brain -Existence of mirror systems in the brain and emergence of bipedal movement might have spurred development of spoken language

3. Communication in Nonhuman Animals

   • Many animals communicate with one another -Prairie dogs -Bee dances -Birdsong
   • Behavior of other animals is closer to true language -Great apes -Cetaceans (dolphins, whales) -Parrots -Dogs

4. Multilingualism and Bilingualism

   • -More than half of the world’s population is bilingual -Children perform better on tests of executive control -Bilingualism is associated with a delay in the onset of age-related dementia
   • Age of learning and proficiency influences brain correlates of multiple language processing -Extent of overlapping activity -Role of dorsolateral prefrontal cortex (DLPC) as language switch -Executive attentional processing by the inferior parietal lobe

5. American Sign Language

   • -Combines language (left hemisphere) and spatial processing (right hemisphere) -Brain imaging shows same patterns of activation for spoken language or ASL -ASL users process movement differently from non-ASL users

6. Stuttering

   • -Producing repetitions or prolonging of sounds -Primarily genetic in origin -Abnormal lateralization of speech areas -High activity in basal ganglia
   • Treatments -Reducing rates at which speech is produced and stress associated with the disorder -Reducing stress

7. Broca

   • Patient ‘Leborgne’ – mute for 20 years, was intelligent and could understand spoken and written language.
   • -Autopsy revealed large cavity posterior region of FL in LH. -8 other patients = similar damage -Region just in front of motor cortex responsible for muscles of vocal cord and mouth. -Damage to RH = no effect on speech production and comprehension -Broca’s area = Left hemisphere of the frontal cortex
   • Inability to speak fluently despite the presence of normal comprehension and intact vocal mechanism
   • Can have difficulty comprehending speech that is grammatically complex, unusual word order or is ambiguous

8. Aphasia

   • Difficulty producing or comprehending speech not produced by deafness or a simple motor deficit; caused by brain damage. -Not aphasia if caused by alcohol misuse, sensory/motor deficit or severing of vocal cords
   • Studying such abnormalities enable neurologist to reconstruct language pathways in the brain.
   • Wernicke’s
     • Inability to understand or to produce meaningful language through sentences, though production of words is still intact.
       • Symptoms:
         • Paraphasia and neologisms -e.g., Anchor = martha argeneth; Pen = minkt -e.g., Where do you work? “Before I was in the one here, I was in the other one.”
         • -Deficit in language comprehension -Unaware of their language comprehension deficits jargon aphasia: the use of inappropriate words producing disjointed speech -Will follow the non-verbal rules of conversation = pausing, taking turns to speak, nodding at appropriate -Sensitive to tone of voice and facial expressions -Reading and writing is often impaired
         • Pure word deafness
   • Comprehension of written words
     • Written word -> visual cortex -> angular gyrus -> Wernicke’s area -> comprehend written word
   • Reading a written word aloud
     • Reading written word -> visual inputs travel through posterior region of corpus callosum to posterior region of frontal lobe (Broca’s area)
   • Conduction Aphasia (repetition Aphasia)
     • An inability to repeat non-words that are heard but the ability to speak normally and comprehend the speech of others.
     • Difficulty reading aloud but can read silently with good comprehension
     • Can repeat concrete words (e.g., bicycle) but not abstract or non-words (e.g., blaynge) -Concrete words can be represented visually -> this information passed to Broca’s area via different pathway
     • Caused by damage to Arcuate fasciculus: Connection b/w Broca’s and Wernicke’s area
     • Destroying the arcuate fasciculus = normal speech production and normal comprehension of auditory and visual information but unable to repeat words and sentences fluently
   • Wernicke-Geschwind Model
     • Theory that explains how the brain processes language
     • Proposes that both the primary auditory (speech) and visual cortex (reading) project to Wernicke’s area where word recognition and comprehension takes place.
     • The translation of mental thoughts into verbal codes is also believed to take place in Wernicke’s area and this information is passed to Broca’s area which produces the motor output necessary for speech.
     • Some information to support this model – but regions more distributed that originally thought.
   • Transcortical Sensory Aphasia
     • Can repeat words and non-words and identify grammatical errors Little understanding of what they are saying Echolaia – person repeats words or phrases just spoken to them
     • Caused by damage to the region of the brain posterior to Wernicke’s area (viz., temporal lobe-parietal lobe borders) but leaves arcuate fasciculus intact.
     • Damage disrupts the flow of info from area decoding phonological info (Wernicke’s area) to the areas determining the meaning of sound.

9. Dyslexia

   • An inability to read correctly despite normal intelligence, motivation and schooling.
   • Developmental disorder but can arise through brain injury (called acquired dyslexia)
   • Most common neurodevelopmental disorder affecting children (5-17.5% of school-aged children)
   • Persistent and chronic condition not caused by delayed development
   • Word-form/surface dyslexia
   • Phonological dyslexia

10. Alexia

    • Pure Alexia
    • Agraphia