The Brain

1. The Brain Language areas The divided brain

2. Language areas • Language, in all its forms, is processed, created and understood in various parts of the brain. • Through research, it has been determined that there is localization of brain function related to language. • The term aphasia is used to indicate an impairment of language. This impairment can show up in language use (speaking for example) or in language processing (comprehension)

3. Language • Based on early research of Paul Broca, Carl Wernicke, Norman Geschwind mapped the basic process of language usage. • For example, when you read aloud– the words register in the visual area—are relayed to the angular gyrus, which transforms the words into an auditory code—which is received and processed by Wernicke’s area—sent to Broca’s area which—controls the motor cortex to pronounce the word

4. Language: localized areas • Broca’s area: controls language expression—usually in the left frontal lobe, controls the muscle movements involved in speech • Discovered by Paul Broca, in 1865. Tan. Patients can comprehend language and are able to sing but struggle to speak. Broca’s aphasia: disruption of the ability to speak

5. Language: localized areas • Carl Wernicke, in 1874, discovered the people with damage to the left temporal lobe could only speak meaningless words. • Wernicke’s area controls understanding of language. Wernicke’s aphasia is the inability to understand language but the ability to speak is not impacted. • The angular gyrus is involved in reading aloud. It processes the visual clues and turns them into code that is understood by Wernicke’s area. Damage to it leaves you able to speak and understand but unable to read aloud.

6. Language • Using fMRI, the neural areas used in language processing can be mapped even further. These studies show that different neural networks are activated for nouns and verbs and that language is processed differently dependent on when you learned the languages. Bilingual from early childhood individuals, use the same area (Broca’s) when recounting events in either language. Those who learn a second language later in life use a larger and adjacent area of the brain when recounting the events in the second language.

7. The brain’s plasticity • The brain’s ability to reshape itself after damage is known as plasticity. Plasticity also refers to the brain’s process of building new pathways based on experience. • The brain is most plastic when we are young. • Brain areas that are not used (temporal lobe area in the deaf)(visual cortex for the blind) often repurpose themselves. For example, the sense of touch (reading Braille) enlarges and spreads to the visual cortex in the blind. Many deaf individuals report having better than normal peripheral vision. The temporal lobe helps process visual stimulation.

8. Neurogenesis • Although it has long been held as true that brain cells are not created later in life, there is new research to indicate that they do. • Neurogenesis is the formation of new neurons. • In 2007, Gould discovered that monkey brains are forming new neurons. These neurons form deep in the brain and then migrate and form connections with other neurons. • There is also new research on the use of stem cells to create new brain cells.

9. Our divided brain • In 1961, Philip Vogel and Joseph Bogen believed that major epileptic seizures were caused by abnormal activity between the two hemispheres across the corpus callosum. • The corpus callosum is a band of neural fibers that connect the two hemispheres and carry messages between the two hemispheres.

10. Split brain • Vogel and Bogen knew that there had been research done on split brains in animals (cats and monkeys) with no ill effects. (Sperry, Myers and Gazzaniga) • The surgery cured the patient of the seizures. • Sperry and Gazzaniga have done extensive research with split brain patients. This has helped us to understand the complementary functions of the two hemispheres.

11. Split brain • The split brain surgery, allows researchers to quiz the hemispheres separately. • In 1967, the HE-ART experiment, led to new knowledge about our processing of visual information and language. • Stare at the dot, as the patient is staring HE-ART is flashed on the screen. HE appears in the left visual field and ART in the right. Left visual field transmits to right hemisphere and vice versa. When asked what they had seen, the patients responded ART. When asked to point with their left hand, they pointed at HE. Each hemisphere knew what it had seen but had to be given an opportunity to express itself.

12. Split brain • The hidden object– patients are shown (to the right hemisphere)an object. When asked what they saw, they cannot say what they saw. When asked to feel hidden objects with the left hand, they can choose the correct object. But do not understand how they chose it. • People with a split brain are in essence people of two minds. Sometimes these minds are at odds with each other. The left hemisphere will try to solve unexplainable actions with logic.

13. Split brain: what have we learned • Left hemisphere: active when we deliberate a decision, when active we are more likely to discount disagreeable information • Right hemisphere: understands simple requests, easily perceives objects, more engaged with quick/intuitive responses, better at copying drawings and recognizing faces, skilled at perceiving emotion and portraying emotion (left side of face) • No activity where only one hemisphere makes a contribution

14. Split brain • Logic not confined to left hemisphere • No evidence that creativity or intuition is an exclusive property of the right hemisphere • Impossible to educate one hemisphere at a time • No evidence that people are purely left-brained or right-brained • (Jerre Levy)

15. Right brain/left brain differences • When perceptual tasks are performed there is increased blood flow, glucose consumption in the right hemisphere • When we speak or calculate, left hemisphere. • Left good at making quick, literal interpretation of language; right excels at making inferences. • Right helps us modulate speech, to make meaning clear. • For example, “What’s that in the road ahead?” as opposed to “What’s that in the road, a head?” • Right seems to orchestrate our sense of self • We have unified brains with specialized parts.