PSB2000 EXAM 4 REVIEW Chapter 16 Lateralization and Language 19a and 19b 1 Under the Wernicke Geschwind model Describe the sequence of activation of language areas following by speech or reading What is the putative role of each area Lateralization unequal representation of various psychological functions in the two hemispheres 2 How do conductive vs expressive aphasias differ Expressive aphasia is the loss of the ability to produce language will exhibit effortful speech Conductive aphasia is expressed by intact auditory comprehension fluent speech production but telegraphic speech poor speech repetition 3 What are 3 ways to measure lateralization in the human brain Sodium amytal test injection numbs one hemisphere interrupts lateralized language Dichotic listening test when auditory inputs compete subject attend to input contralateral to language areas Functional brain imaging 4 Define commisures corpus callosum Commisures tracts that cross between hemispheres Corpus callosum largest white matter structure in brain connects cerebral hemispheres 5 Describe the findings of split brain research in cats and humans In humans relate to language lateralization cerebral hemisphere Most sensory and motor info pertaining to one half of the body is represented in the contralateral Control group intact communication between hemispheres task learning occurs in both hemispheres Experimental group transected optic chiasm and corpus callosum info from each eye restricted to ipsilateral hemisphere Task learning must occur in each hemisphere Similar deficits in other sensory systems fine tactual discrimination fine motor responses In patients with epilepsy corpus callosum cut optic chiasm still intact Tactile or visual cues to each hemisphere can allow that hemisphere to enact a response motor input and output are contralateral to hemisphere in question emotional response Only the left hemisphere can enact a verbal response sometimes tries to explain discrepancy helping hand phenomenon Left brain also has weaknesses hemispheres function independently on some tasks such as chimeric figures test Left hemisphere handles language and movement control but right hemisphere handles spatial and musical ability 6 Why is lateralization evolutionarily useful to initiate conflicts Right hemisphere fish more attentive to conspecific on left side while monitoring predator and Left hemisphere toad tongue strikes primarily on right side right eye needed for chicken to discriminate between pebbles and grain 7 What are the three theories of language lateralization Analytic synthetic theory left hemisphere is logical and analytical R hemisphere is holistic not strongly supported by data Motor theory left hemisphere specialized all fine motor movements preference for feeding with right side of body birds dogs monkeys also have areas involved in vocal communication lateralized to left hemisphere Linguistic theory left hemisphere specifically evolved for language deficits can occur in other language modalities besides speech but don t necessarily interrupt non lingual communication 8 What is an animal model of language and what does it have in common with human language Birdsong as a model of language Similarities lateralized learned critical period during development Differences songbird language and music on both sides of brain we can speak about things that are not tangible 9 What is the motor theory of speech production How does it relate to mirror neurons The theory that perception of speech involves activation of the same areas as production of speech fine motor control allows for language mirron neurons active during listening 10 What are the predictions of the Wernicke Gerschwind model regarding selective lesions to the following structures Broca s area Wernicke s area arcuate fasciculus angular gyrus Broca s aphasia expressive aphasia normal comprehension speech retains meaning but is slow labored disjointed and poorly articulated Wernicke s aphasia receptive aphasia poor comprehension of both written and spoken language speech that is meaningless but retains normal structure rhythm and intonation doesn t recognize that words spoken are incoherent Conduction aphasia normal comprehension and spontaneous speech difficulty repeating word 11 What are some inaccuracies of the Wernicke Gerschwind model How do the findings of Leech and Saygin refute the model How do the findings of Demasio et al refute the model Model developed studying patients with brain injuries typically nonselective lesions adjacent areas or underlying white matter also damaged Aphasias sometimes occur without damage to the Wernicke Geschwind areas Damage to Wernicke s or Broca s areas alone often does not produce permanent aphasias Most aphasias have both expressive and receptive symptoms Cognitive approach Constituent cognitive processes simple cognitive processes that combine to produce complex cognitive processes and that are assumed to be mediated by neural activity in particular parts of the brain Leech and Saygin 2011 more sensitive fMRI machine leads to enhanced spatial precision receptive task with 2 conditions language or background sounds Blue and Red show regions in which pixels that differ under two conditions are interspersed Language areas are not large distinct nuclei language neurons mingle with non language neurons Domasio 1996 expressive task name the stimulus image 3 categories famous face animal or tool PET scanning activity was seen well outside Wernicke s area different categories activated slightly different areas category specific organization 12 How do surface and deep dyslexia differ Surface dyslexia inability to recognize words that don t follow normal phonetic rules looking at what the word is made up of Deep dyslexia an inability to sound out unfamiliar words or non words Could pronounce words that they learned before the dyslexia was acquired will sometimes respond with a word that is related to the meaning of a word they are attempting to read 13 How does the study by Palesu reflect a basis for dyslexia in phonological processing English speakers twice as likely to be diagnosed with dyslexia compared to Italian speakers English has 40 phonemes with 1120 possible spellings Italian has 25 phonemes with 33 possible spellings PET scanning showed similar deficit in activation of L temporal lobe across languages Common neural pathology manifestation depends on phonological complexity PP20 Emotion and Aggression 1
View Full Document
Unlocking...