Corpus Callosum. Fig3_19. Right & left hemispheres. Each half of your brain sees the opposite half of your visual world

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1 Right & left hemispheres are only connected by commissures. Right & left hemispheres Figure 16.1 Corpus Callosum Fig3_19 Corpus callosum Most important commissure connecting the 2 hemispheres, allowing constant communication Hemispheres In some ways the hemispheres are symmetrical in function Visual Fields Each half of your brain sees the opposite half of your visual world and processes left body sensations. And visa versa for the left hem. 1

constant communication Hemispheres In some ways the hemispheres are symmetrical in function Visual Fields Each

2 Cerebral Lateralization The unequal representation of functions in the 2 hemispheres Seizure period of excessive synchronized neural activity Epilepsy - Recurring seizures; about 1-2 in 100 people has epilepsy; occurs in many forms Sometimes involve whole cortex & are due to inherited difference in brain chemistry (decreased release of or receptors for the inhibitory transmitter GABA) primary epilepsy Or may follow brain injury secondary epilepsy Seizure activity begins at the injured spot (the focus ) & are called focal or partial seizures Because the brain is so conductive, partial seizures may spread to other brain areas Cutting the corpus callosum prevents spread of seizure activity from 1 side to the other. Became known as split brain surgery although the entire brain is not split. X Corpus Callosum Split Brain Research Learning about right brain/left brain differences Just the corpus callosum is cut. 2

epilepsy Or may follow brain injury secondary epilepsy Seizure activity begins at the injured spot (the focus ) & are called focal or partial seizures Because the brain is so conductive, partial

3 Roger Sperry Testing of Split Brain Patients Left Brain Sees a Ball Right Brain Sees a Hammer I see a baseball But left hand can select the hammer, indicating hammer was perceived but couldn t be verbally identified by right hemisphere. ZqKg Independent Functioning of the Hemispheres After Surgery Different wishes Can simultaneously do different tasks with each hand N S9Dc&feature=related Alda segment Using touch to test a split brain patient WGw1DI Left Hemisphere Subjective Interpreter Gazzaniga proposes the LH provides our inner voice narrative interpretation as we try to make sense of the world. Also provides the verbal reconstruction of our memories. 3

v=hpuphfw ZqKg Independent Functioning of the Hemispheres After Surgery Different wishes Can simultaneously do different tasks with each hand N http://www.youtube.com/watch?

4 Lateralization Case studies of the effects of brain damage revealed language problems almost always associated with left brain damage Left hemisphere is normally dominant for language-related abilities in ~95% of righthanders and -80% of left-handers. The degree of dominance varies. Speech production is more lateralized than comprehension. Right hemisphere is dominant for other functions. Math Table 16.1 Larger on left even in infants Figure

righthanders and -80% of left-handers. The degree of dominance varies.

5 Left is dominant for language in both right-handers and left-handers, but some lefties may have some right hemisphere language as well. Broca s producing speech Wernicke s comprehension of speech Aphasia: language problems due to brain damage *The greater the damage in the vicinity of Broca s area, the greater the difficulty producing speech: Broca s aphasia or nonfluent aphasia Both spoken & signed language affected Affects writing & gesturing too Results in telegraphic speech (nouns & verbs); comprehension is good for nouns and verbs But affects the use & understanding of those little grammatical words (like prepositions), endings, & meaning conveyed by word order Expressive Aphasia Case 1 Wernicke s Aphasia or Fluent Aphasia Damage to Wernicke s area more broadly affects speech comprehension/comprehensibility: can talk but not make sense. Anomia- can t come up with the right word; uses made up words, mixed up phonemes, talks around in circles Aphasias *Symptom severity also related to degree of lateralization. Wernicke-Geschwind too limited much larger areas of the brain are involved in language processing o18aa 5

producing speech: Broca s aphasia or nonfluent aphasia Both spoken & signed language affected Affects writing & gesturing too Results in telegraphic speech (nouns & verbs); comprehension is good for

6 Nonhuman Precursors of Language Chimps picking & combining symbols to make & respond to requests/questions Premack Sarah plastic symbols Rumbaugh Lana symbols on keyboard Chimps and gorillas learning American sign language Gardners Washoe & others Patterson Koko the Gorilla Animals showing complex responses to spoken language Savage-Rumbaugh Kanzi selecting photos (also uses symbol board) & following novel commands d Pepperberg African Gray Parrot Alex vocalizes his responses Koko the Gorilla UEi2ko about 7:20 ddze4 Recovery from Rasmussen s Syndrome Surgery GnlMV0 6

following novel commands http://www.youtube.com/watch?v=2dhc2zepjfe&feature=relate d http://www.youtube.com/watch?v=wrm7vtriiis&feature=relmfu Pepperberg African Gray Parrot Alex vocalizes his responses http://www.

The Brain. Hemisphere-specific Deficits. Broca s Area 1/2/11. Cerebral Specialization

The Brain. Hemisphere-specific Deficits. Broca s Area 1/2/11. Cerebral Specialization The Brain Cerebral Specialization Hemisphere-specific Deficits Language deficits Associated with left hemisphere damage First noticed in the 1800 s Broca Examined deficits carefully and methodically Became