语言学概论-brain-and-language.ppt

Brain and LanguageBrain and Language.The Human BrainIntroductionIntroductionuThe complexities of human cognitive abilities and language acquisitionuBrain is the source of human language and cognition.The most complex organ of the bodyCortex(gray matter)a)decision-makingb)memoriesc)grammarWhite matterContralateral function.The Localization of LanguageWhich parts of the brain are responsible for linguistic abilities?Franz Joseph Gall LocalizationOrganology(phrenology)Brain is not a uniform mass.AphasiaRelationship between brain and languageLanguage disorder caused by disease or traumaBrocas area v.s.Wernickes areaLateralization.Most aphasics do not show total language loss.The language disorder is generally related to the location of the brain damage.Brocas aphasia injuries to the left frontal lobe Wernickes aphasia injuries to the left temporal lobe Brocas areaWernickes area.I.Brocas aphasia (agrammatic aphasia)Syndromes:A.Labored speech B.Word-finding difficulties C.Problems in forming sentences with the rules of syntax.D.Language produced is often agrammatic Q:What is“agrammatic”?A:It frequently lacks articles,prepositions,pronouns,auxiliary verbs.lacks function words The omission of function words in the speech of agrammatic aphasics shows that function words are mentally distinct from content words.E.May typically omit inflections the past tense suffix ed e.g.I watch TV for three hours this morning.the third person singular verb ending s e.g.She like playing the piano.ededs s.F.Have difficulty understanding complex sentences in which they cannot rely on their real-world knowledge.more difficulty for aphasia people:e.g.Which girl did the boy kiss?less difficulty for aphasia people:e.g.Which book did the boy read?.II.Wernickes aphasiaWernickes aphasics can produce fluent speech and adhere to the rules of syntax.Syndromes:A.Their language is often semantically incoherent.fork a need for a schedule when asking about poor vision My wires dont hire right.B.Have difficulty naming objects presented to them C.Have difficulty choosing words in spontaneous speech often produce jargon and nonsense words .Jargon aphasiaSevere Wernickes aphasia is often referred to as jargon aphasia.Syndrome:substitute new word for original word.Word substitutions that aphasic patients produce also tell us about how words are organized in the mental lexicon.sounds meaning pool tool table chair sable table boy girl crucial crucible.III.Acquired dyslexicsDyslexia:a condition that makes it difficult for someone to read and spell.Acquired dyslexics:people who become dyslexic after brain damage.The similar phenomenon of word substitutions may also happen to acquired dyslexics.(examples on page 9).The similar syndrome of the omission of function words in the speech also happens to acquired dyslexics.(examples on page 10)These errors show that the mental lexicon has content words and function words in different compartments.IV.Tip-of-the-tongue phenomenonThe tip-of the-tongue phenomenon is the failure to retrieve a word from memory,combined with partial recall and the feeling that retrieval is imminent.word-finding difficulties in speaking TOT.Word finding difficulties is the fate of many aphasics.Anomia:the inability to find words you wish to speak.V.Deaf Aphasic patients Deaf patients with lesions in Brocas area Syndromes:dysfluent and agrammatic sign productionDeaf patients with lesions in Wernickes area Syndromes:have fluent but often semantically incoherent sign language.ConclusionDeaf signers with damage to the left hemisphere show aphasia for sign language similar to the language breakdown in hearing aphasics.Brain Imaging TechnologyNoninvasive brain recording technologies1.Computer tomography(CT)2.Magnetic resonance imaging(MRI)Reveal lesions in the living brain shortly after the damage occurs.3.Positron emission tomography(PET)4.Functional MRI(FmrI)5.Single photon emission CT(SPECT)Provide images of the brain in action.Other scanning techniques measure metabolic activity in particular areas of the brain1.Magnetic encephalography (MEG)This technique shows us how the healthy brain reacts to particular linguistic stimuli.Separation of the cognitive systemEvidence:1.fMRL&PET scans Differential activation in the normal brains in just those sites that were damaged in the aphasics.2.neurological and behavioral findings .Brain Plasticity and Lateralization in Early LifeLateralization of language to the left hemisphere is a process that begins very early in life.Infant as young as one week show a response right hemisphere music left hemisphere language.The study found:during smiling greater opening of the left side of the mouth during babbling greater opening of the right side of the mouth more left hemisphere involvement even at this very early stage of productive language development.the right hemisphere can take over the language functions that would normally reside in the left hemisphere.Hemispherectomy1.one hemisphere of the brain is surgically removed2.Treat otherwise intractable cases of epilepsy.Doing left hemispherectomy After language acquisition has begun In children they experience an initial period of aphasia and then require a linguistic system that is virtually indistinguishable from normal children.In adults They inevitably lose severe language function .Right hemisphere plays a role in the earliest stages of language acquisitionChildren with prenatal,perinatal,or childhood brain lesions in the right hemisphere babbling and vocabulary learning in the left hemisphere ability to form phrases and sentencesAlso,children who undergo right hemisphere hemispherectomy before two years of age dont develop language.ConclusionHuman brain is essentially designed to specialize for language in the left hemisphere but that the right hemisphere is involved in early language development.Under the right circumstances,the brain is remarkably resilient and that if brain damage or surgery occurs early in life,normal left hemisphere functions can be taken over by the right hemisphere.Spilt Brainreview：What is the corpus callosum?What is the word“spilt brain”?A.Definition -an surgical technique to cut some or all corpus callosum of a personWhat will happen if people lose their corpus callosum?-no communication between the left and the right hemispheres -function independently.An experiment on split-brain patients to show what will happen to people when the corpus callosum is severed.What significant information we get from this experiment?-infer to the language lateralization in the left hemisphere -knowing that two hemispheres of brain have different capacities Function of two halves：the right:pattern-matching tasks,imagination,art awareness the left:more superior in language,logical thinking,mathematic skills.Conclusion What is the purpose for the author to mention the term“split brain”?-one of the evidence to explain the lateralization of language and to know different cognitive behavior are controlled in different parts of the brain(namely localization).Other experimental evidence of brain organization.an experimental technique that uses auditory signals to observe the individual hemispheres of human brain.Right ear linguistic stimuliLeft ear nonverbal stimuliDichotic listening.ERPS(event-related brain potentials)the electrical signal emitted from the brain in response to different stimuliResult Left brain is specialize for language.