Hem 1 Hemispheric specialization and the corpus callosum Hemispheres look symmetrical but are they Many examples of functional symmetry e g sensory and motor areas Early examples of functional asymmetry hemispheric specialization Broca s aphasia Wernicke s aphasia Hem 2 Damage to left frontal lobe Broca s area near motor cortex Check this video out https www youtube com watch v f2IiMEbMnPM Expressive or productive aphasia Can comprehend but difficulty speaking and writing Speech is slow belabored and agrammatic Can curse sing Theory Broca s area stores the articulation codes that turn words into muscle actions necessary to produce them Hem 3 Wernicke s aphasia 1874 https www youtube com watch v 3oef68YabD0 Damage to left temporal lobe Wernicke s area near auditory cortex Receptive aphasia Speech is fluent but nonsense word salad Cannot comprehend Theory Wernicke s area converts sensory analysis performed by auditory cortex into meaningful words Check this video out https www youtube com watch v aVhYN7NTIKU Also https www youtube com watch v 3oef68YabD0 Hem 4 Interesting variations Linguistic functions are not always mediated by left hemisphere Almost all right handed people have Broca s area in the left hemisphere But in some left handed people it is in the right hemisphere Age effects Sex differences Hem 5 The two hemispheres communicate via the corpus callosum an axonal pathway of 500 000 000 axons Split brain studies severing the corpus callosum Why and how split the brain Epilepsy one bad apple can spoil the barrel If the two hemispheres process different kinds of information how do they communicate Strategy limit information to one hemisphere and see how the information is processed Visual presentations to contralateral visual field Somatosensory presentations to contralateral hand Hem 6 Split brain studies Sperry and Gazzaniga Hem 7 Everything to the left of the midline left visual field is projected to the right hemisphere x Everything to the right of the midline right visual field is projected to the left hemisphere Hem 8 Everything to the left of the midline left visual field is projected to the right hemisphere x Everything to the right of the midline right visual field is projected to the left hemisphere Hem 9 x Hem 10 x Hem 11 Right hemisphere specialization s Spatial relations facial recognition Emotional tone Prosody gesticulation Tonal memory Some basic language comprehension but not specialized for language Hem 12 Hemispheric cooperation and conflict how do the two hemispheres get along