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Ch_15 - Chapter 15 Chapter 15 Language and the Brain...

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Unformatted text preview: Chapter 15 Chapter 15 Language and the Brain Language and the brain Language and the brain Neurolinguistics: field that studies the relationship between language and the brain Neurologists Psychologists Speech­language pathologists Neuroanatomy Neuroanatomy Human nervous system: Brain Spinal cord Brain Cerebrum, which is the main mass of the brain, Brainstem, group of important structures at the base of the brain, that connect the brain to the spinal cord Cerebellum, attached to the back of the brainstem and is important for coordination of movements Brain Brain Brain’s most basic functions Causing movement Processing sensation The brain sends motor commands to the muscles of the body by way of the brainstem and spinal cord, and the spinal cord transmits sensory info like touch and pain from various parts of the body. Hemispheres Hemispheres Cerebrum Right hemisphere Left hemisphere This is what is meant when people refer to right brain versus left brain. Primary motor cortex (M1) Posterior parietal cortex Supplementary motor cortex (SMA) Premotor cortex (PMA) CELL BODY Dendrites Myelin sheath AXON Schwann cell Node of Ranvier Synaptic terminals Nucleus Synapses Neurons Neurons Neuron: Cell body: receives signals from other neurons, process info Axon: sends signals to other neurons Cerebral cortex Cerebral cortex Outer layer of cerebral hemisphere Made up of gray matter = cell bodies of neurons Under cortex = white matter= axons Parietal lobe Frontal lobe Occipital lobe Temporal lobe Cerebellum Lobes Lobes Each cerebral hemisphere consists of 4 lobes: Frontal lobe: starts in the front, just behind the forehead and goes almost half way back to the back of the head. It sends the most of the motor commands to the muscles of your body that cause movement. The frontal lobe is important for personality, planning and decision making. Lobes Lobes Parietal lobe: starts behind the frontal lobe. It processes most of the sensory memory information from the body: pain, temperature, touch, sense of body position. Occipital lobe: in the back of the brain. It is responsible mainly for vision. Lobes Lobes Temporal lobe: the extension along the side of the brain. It underlies the ear. It is important for hearing and the processing of both auditory and visual input. Primary Motor Cortex Primary Motor Cortex Mistake in book – p163. The gray strip in front of the 3 is actually the PMC, not the area labeled 3. Primarily responsible for controlling the muscles of your body. In both the L and R hemispheres The PMC in the L hemisphere (shown in book) controls the R side of your body. The PMC in the R hemisphere controls the L side of your body. Primary motor cortex (M1) Posterior parietal cortex Supplementary motor cortex (SMA) Premotor cortex (PMA) Brain Brain Homunculus: diagram that shows you which parts of the primary motor cortex are devoted to controlling which parts of the body http://faculty.washington.edu/chudler/flash/hom.htm http://faculty.washington.edu/chudler/flash/hom.ht Cortical mapping: procedure of determining the functions of areas of the cerebral cortex by stimulating them directly Aphasia Aphasia Aphasia: an impairment of language function due to localized brain damage which leads to difficulty understanding and/or producing linguistic forms. Broca’s Aphasia: characterized by slow, effortful, telegraphic (usually only nouns andverbs, no grammatical morphemes), nonfluent speech (speaking at a slow rate with many pauses), and usually only mild problems understanding speech. Wernicke’s Aphasia: characterized by fluent speech (speech produced at a normal rate and without struggle). Conduction Aphasia: characterized by intact auditory comprehension – they understand spoken words, but poor repetition of verbal materials. Broca’s area Broca’s area Area labeled 1 in your book It is named after Paul Broca, a French doctor. In the 1860s, he discovered that damage to this area in the left hemisphere (but not the right) caused extreme difficulty with speech production. Broca’s aphasia Broca’s aphasia The following is an excerpt from The Shattered Mind (1974). David Ford, was a 39 year old Coast Guardsmen who suffered a stroke and had Broca’s aphasia. In response to a question about his work (radio operator), he said: “I’m a sig…no…man…uh, well… again.” When asked what happened to his speech, he said: “Head, fall, Jesus Christ, me no good, str, str…oh Jesus…stroke.” Wernicke’s area Wernicke’s area The area labeled 2 in the book figure (p163) at the back of the top surface of the temporal lobe is Wernicke’s area. Carl Wernicke, a German doctor in the 1870s reported that patients with damage in this area had difficulty comprehending speech. Wernicke’s aphasia Wernicke’s aphasia The following is an excerpt from The Shattered Mind (1974). Philip Gorgan, a 72 year old butcher, had Wernicke’s aphasia. In response to a question about why Mr. Gorgan was in the hospital, he said: “Boy, I’m sweating, I’m awfully nervous, you know, once in a while I get caught up, I can’t mention the tarripoi, a month ago, quite a while, I’ve done a lot well, I impose a lot, while, on the other hand, you know what I mean, I have to run around, look it over, trebbin and all that sort of stuff.” Arcuate fasciculus Arcuate fasciculus The area labeled 4 in the book is the arcuate fasciculus, not part of the cortex. not on the surface of the hemisphere. It is a bundle of white matter fibers (a bunch of axons) found below the cortex in the region between Broca’s and Wernicke’s. It provides a connection between those two areas. Lesions in this area can produce conduction aphasia. Motor cortex Somatosensory cortex Sensory associative cortex Pars opercularis Visual associative cortex Broca’s area Visual cortex Primary Auditory cortex Wernicke’s area Localization Localization Localization: attributing very specific language functions to specific brain regions. Based on the assumption that the brain is like other organs in the body Gross oversimplifications TOT phenomenon TOT phenomenon TOT phenomenon: when you know the word you want to say, but you can’t retrieve it. Studies have shown that someone in a TOT state can usually: say what the initial sound of the word is say how many syllables it has describe the stress pattern of the word TOT Phenomenon TOT Phenomenon Malapropisms: production of similar sounding but incorrect words while in the TOT state These characteristics of the tip of the tongue state have been used to infer how our mental dictionary, our lexicon, is organized. Slips of the tongue Slips of the tongue Slip of the tongue or Spoonerism: a speech error resulting from an exchange of phonemes or words within a phrase. Exchange of word­initial sounds Exchange for word­final sounds Carryover/perseverative/L to R slip Anticipatory/R to L slip Slips of the tongue Slips of the tongue Used as evidence for some of the syllable structure constituents and phonotactic rules we have talked about The fact that in “shu flots” the first 2 consonants of the 2 words are exchanged suggests that at some level, an initial consonant cluster is a distinct unit of the syllable. That unit is the onset. The same is true for the nucleus and the coda. There are slips of the tongue that involved exchanges or repetitions of nuclei and codas. Dichotic listening tasks Dichotic listening tasks These tests are based on the fact that just like the L hemisphere of the brain controls the R half of the body, information heard by the R ear goes primarily to the L hemisphere. Both the sensory and motor pathways are crossed Right­ear advantage for language Left­ear advantage for processing non­ linguistic sounds Critical period Critical period There seems to be a critical period for language learning from birth up until puberty. If a child does not acquire language during this period, he or she will have great difficulty learning it later on. Genie Genie Genie’s story came out in 1970. First 13 years of her life tied to a chair in a dark room and was beaten if she made any noises, so she did not acquire any language. Dichotic listening test: strong left­ear advantage for language Rehab programs for training R hemispheres of people with aphasia due to L hemisphere stroke to take over language functions, but they have mixed results ...
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