11 brain & language
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Chapter 11
Human Processing: Brain, Mind and Language
The Human Brain
• composed of approximately 10 billion nerve cellsneurons
• Axons: take informationaway from cell body
• Dendrites: bring informationto cell body
Sourse: http://faculty.washington.edu/chudler/cells.html
Source: http://faculty.washington.edu/chudler/cellpyr.html(Image used with permission of The Slice of Life.)
Pyramidal neuron in the cerebral cortex.
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Source: http://faculty.washington.edu/chudler/functional.html
Cerebral cortex
The Cerebral Hemispheres
Source: http://designweb.otago.ac.nz/grant/psyc/TWOBRAIN.HTML
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The Corpus Callosum• bundle of nerve fibres that serves as connection
between the 2 hemispheres.
Source:http://www.macalester.edu/~psych/whathap/UBNRP/Split_Brain/Corpus%20Callosum.html
Source: http://faculty.washington.edu/chudler/split.html
Contralateral Organization of Brain• in general, the left hemisphere controls movement on right side
of body, and the right hemisphere controls movement on left side of body
• In 95% of right-handers, the left sideof the brain is dominant for language.
• Even in 60-70% of left-handers, theleft side of brain is used for language
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Source: http://hypatia.ss.uci.edu/psych9a/lectures/lec2notes.html
Contralateral Organization of the Visual Field
Ipsilateral Organization
• Ipsilateral connections are same side connections
• Some ipsilateral connections are found in theauditory cortex
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Brain Imaging Techniques
1. CT Scans
2. PET Scans
3. Magnetic Resonance Imaging (MRI)
4. Functional Magnetic Resonance Imaging (fMRI)
5. Event-Related Brain Potentials (ERPs)
1. Computed Tomography (CT) Scan• uses a series of x-ray beams passed through head• creates cross-sectional images of the brain• shows the structure of the brain, not the function
Source: http://faculty.washington.edu/chudler/image.html
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2. Positron Emisssion Tomography (PET) Scans? radioactive material is injected or inhaled? a scanner detects this material when it breaks down ? provides a functional view of the brain
Source: http://faculty.washington.edu/chudler/image.html
3. Magnetic Resonance Imaging (MRI)• uses detection of radio frequency signals produced
by displaced radio waves in a magnetic field• a scanner detects this material
when it breaks down • provides an anatomical view of the brain
Source: http://faculty.washington.edu/chudler/image.html
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4.functional Magnetic Resonance Imaging (fMRI)• detects changes in blood flow to particular areas of
brain• provides both anatomical and functional view of the
brain
Source:http://www.fmri.org/fmri.htm
5. Event-Related Brain Potentials (ERPs)• record electrical signals emitted from different areas of
the brain• reflect brain activity that is specifically related to some
stimulus or other event
Source: http://faculty.washington.edu/losterho/erplab.htm
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Source: http://faculty.washington.edu/losterho/erps.htm
Event-Related Brain Potentials (ERPs)
Evidence for Modularity
1. Split brain studies
2. Dichotic Listening studies
3. Aphasia
4. The autonomy of language
Plasticity
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1. Split Brain Studies
• corpus callosum severed as treatment for epilepsy• visual stimuli are presented simultaneously to the right
and left half of a screen, and the physical objects are placed within reach of either the left or right hand of the subject
• subject fixates on centre of visual display• “key ring” example: key reaches right hemisphere
ring reaches only left hemisphere
Split Brain Study Tasks1.Report what they saw:• Subjects within intact corpus callosum:
Report seeing “key ring”• Subject with split corpus callosum:
Report only seeing word ringv key projected to mute half of brain, and can’t be
transferred to left (speaking) side of brain
2. Reach out and touch what they saw with left hand• Subject with split corpus callosum:
touches keyv contrast in response if language is used
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Split Brain Study Tasks
New Developments• keep the back of corpus callosum – the splenium, in tact• seizures relieved, but retains some interhemispheric communication
Source:http://hypatia.ss.uci.edu/psych9a/lectures/lec2notes.html
2. Dichotic Listening Test
• two different auditory stimuli are presented simultaneouslythrough earphones to the left and right ears
• the listeners must report what they hear
Source: http://grove.ufl.edu/~tomomi/Intro/Lecture26/sld005.htm
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2. Dichotic Listening Test (cont’d)
• linguistic stimuli are more accurately reported whenpresented to the right ear
eg. boy to right ear; girl to left earRight-ear advantage
• non-linguistic stimuli are more accurately reported when presented to the left ear
eg. coughing to right ear; laughing to left earLeft-ear advantage
2. Dichotic Listening Test (cont’d)
• processing of acoustic signal dependent upon it beingperceived as a linguistic or non-linguistic stimuli
eg. Syllables contrasting in tone (pitch contours)
Thai: a tone languageSpeakers show a right-ear advantage
English: not a tone languageSpeakers do not show a right-ear advantage
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Speaking a written word
written text
primary visual cortex
Posterior speech area(including Wernicke’s area)
Broca’s area
Primary mortor cortex
Source:http://faculty.washington.edu/chudler/lang.html#speak
Speaking a heard wordspoken word
primary auditory cortex
Posterior speech area(including Wernicke’s area)
Broca’s area
Primary mortor cortex
Source:http://faculty.washington.edu/chudler/lang.html#speak
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Broca’s Aphasia• often referred to as agrammatic• problems with production: slow, slurred speech • difficulty with syntax• interpretation requiring syntactic analysis can also be
be problematicThe dog chased the car. (okay)The cat chased the dog. (confusing)
Broca’s Area
Source:http://faculty.washington.edu/chudler/lang.htmlImages: Courtesy of Sice of Life
3. Aphasia
Broca’s Areainvolved in speech productionand syntactic analysis
Broca’s Aphasia Speech SampleHudson, Grover. 2000. Essential introductory linguistics.Blackwell. Oxford.
Yes… ah… Monday… ah… Dad and Peter Hogan, and Dan… ah… hospital… and, ah… Wednesday… Wednesday, nine o’clockAnd ah Thursday… ten o’clock ah doctors… two… two… andDoctors and ah… teeth…
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Wernicke’s Aphasia
• comprehension difficulties• characterized by verbal fluency without coherence
Source:http://faculty.washington.edu/chudler/lang.htmlImages: Courtesy of Sice of Life
Wernicke’s Area
Wernicke’s Aphasia Speech SampleHudson, Grover. 2000. Essential introductory linguistics.Blackwell. Oxford.
Well, I had trouble with… oh, almost everything that happened form the eh, eh… Golly, the word I can remember you know is ah… When I had the… ah biggest… ah… that I had trouble with, you… that the trouble with,and I still have a … the ah different… The things I want to say… ah..
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Jargon Aphasia• substitution of one phoneme for another
sable for table• some produce long sequences of uninterpretable “jargon »• show that knowledge of sound sequences can be
disassociated from meaning
Acquired Dyslexia• patients who could read prior to lesion substitute when
reading word lists• may not always substitute same word
S-applaud R1-laugh R2-cheers• some only have trouble with grammatical morphemes
S-which R-no!S-witch R-witch
• such substitutions indicators of lexical organization
4. The Autonomy of Language
Specific Language Impairment (SLI)• acquisition of language is impaired, but general intelligence
develops normally
Contrast• development of language, despite delays in other cognitive
areas
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5. Plasticity
• originally thought that connections between neuronsdeveloped early, became fixed and could not be changed
• now some strategies have been developed to overcomelanguage processing problems by modifying brainnetworks
Learning a New Language Task (PET)
UnpracticedTask: hearing a text for a new
language taskHighest brain activity• temporal lobe – responsible for
hearing perception• prefrontal cortex – responsible for
understanding language
PracticedTask: knows the task, is spelling outHighest brain activity• Broca’s area - responsible for
the motor control of voice, Source: http://www.epub.org.br/cm/n01/pet/pet.htm
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Prior to Intervention• Brain activity of 10 year old boyas he identifies sounds of words• reading level: 8 years old
After Intervention• Brain activity after 8 weeks ofspecialized training
• reading level increased by 3 years• images indicate brain activity
changed as well
Source:http://web.sfn.org/content/Publications/BrainBriefings/brain_lang_reading.html
Teaching Reading Strategies : Brain Activity
Language Processing
Psycholinguistics• area of linguistics associated with linguistic performance
The Speech Signal• problem of segmentation• study of spectrograms to learn about acoustic components
that reflect articulatory features of speech sounds
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Source: http://depts.washington.edu/phonlab/mystery/ Robert Hagiwara
bead bid bade bed bad
bod bawd bode buhd booed
Spectrogram
Speech Perception and Comprehension
The Mental Lexicon• information about sound, spelling, syntactic category andmeaning
Lexical Access• period when information about lexical representation
is made available
Word Recognition• outcome of selection phase
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Top-Down Processing• uses semantic and syntactic information to process
sensory input• subjects make fewer identification errors on word
recognition tasks if words occur in:a) sentences rather than in isolationb) meaningful sentences rather than nonsense onesc) grammatical sentences rather than ungrammatical ones
• subjects understand words even if with missing phonemesHear wheel in a sentence even if wh is missing
Bottom-Up Processing• comprehension is based solely on incoming sensory input
Factors Affecting Word Recognition
Frequencyhigher frequency – faster recognitionPrimingFaster recognition for semantically related words
doctor nurse recognized faster than flowerReal WordsRecognized faster than nonsense wordsRecencymore recently used words accessed more quickly
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Syntactic Processing
Garden Path Sentencesharder to process; require back-tracking
1. The bus driven past the school stopped.
2. The horse raced past the barn fell.
3. The horse that was raced past the barn fell.
Speech Production
Planning Unit• speech errors demonstrate that the planning unit
is greater than phonetic segments or individual words
There are many churches in our minister forThere are many ministers in our church
Application and Misapplication of Rulesan istem for a systema burly bird for an early bird
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