BIOPSYCH 0505 Edition 1nd Lecture 21 Outline of Last Lecture I Brain Mechanisms A Original view 1 Ventromedial hypothalamus 2 Lateral hypothalamus B New research 1 Ventral noradrenergic bundle II From the lateral hypothalamus A Melanin concentrating hormone and orexin B Paraventricular nuclei Outline of Current Lecture I Lateralization and the split brain discoveries A Marc Dax B Paul Broca 1 Left hemisphere involved in aphasia 2 Broca s aphasia C Wernicke s aphasia D Apraxia discovered by Liepmann II Cerebral lateralization of function A Cerebral commissures B Corpus callosum C Tests of cerebral lateralization 1 Sodium amytal test 2 Dichotic listening test 3 Functional brain imaging III Speech lateralization and handedness A Left hemisphere is dominant for speech B Sex differences in brain lateralization C Split brain commissurotomy procedure D Myers and Sperry Current Lecture I Lateralization and the split brain discoveries A Marc Dax These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 1 First to report left hemisphere involvement in speech disorders caused by brain damage 2 Language is dominant in the left hemisphere B Paul Broca 1 Left hemisphere involved in aphasia speech disorder 2 Broca s aphasia a Poorly articulated speech ungrammatical telegraphic speech b Nnomia which is a naming deficit c Agraphia which is a writing impairment d Left inferior frontal cortex and the 3rd front gyrus are damaged C Wernicke s aphasia 1 Poor comprehension of spoken and written language 2 Fluent and spontaneous speech but it is nonsensical 3 Paraphasia 4 Alexia reading impairment 5 Left superior temporal gyrus is damaged D Apraxia discovered by Liepmann 1 Difficultly of movement on command on either side of the body but can spontaneously move 2 Associated with the left hemisphere II Cerebral lateralization of function A Cerebral commissures connect two halves of the brain via projection fibers B Corpus callosum 1 Transfers info between the two hemispheres 2 When cut each hemisphere functions independently C Tests of cerebral lateralization 1 Sodium amytal test a Anesthetize one hemisphere and check for language function b Tries to look at each hemisphere individually 2 Dichotic listening test hearing different sounds in each ear at the same time and usually more sounds are heard on the dominant hemisphere side 3 Functional brain imaging a fMRI or PET used to see which half is active when performing a language test b Tests spatial reasoning III Speech lateralization and handedness A Left hemisphere is dominant for speech for both right handed and left handed individuals yet left handed people have a greater variability B Sex differences in brain lateralization 1 Some evidence suggests that the male brain is more lateralized than the female brain 2 McGlone study of unilateral left hemisphere stroke victims that found that men were three times more likely to have aphasia 3 Some fMRI studies show that females tend to use both hemispheres in language related tasks C Split brain commissurotomy procedure 1 Separates the corpus callosum to help epileptic patients 2 Concluded that the corpus callosum was not necessary to function normally but it did help cease seizures in epileptic patients D Myers and Sperry 1 Studied split brain cats 2 Transected the corpus callosum and optic chiasm so that the visual info could not cross the contralateral hemisphere
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