Neuroscience Lecture Notes PDF

Scantron Form 20420 # pencils Human Neuropsychology Lecture 5 BIO N173 / PSY 163/ PSYCH 162 Laterality, Asymmetry, and Hemispheric Disconnection  Left Brain vs. Right Brain What are some left vs. right differences you’ve heard about...

Scantron Form 20420 # pencils Human Neuropsychology Lecture 5 BIO N173 / PSY 163/ PSYCH 162 Laterality, Asymmetry, and Hemispheric Disconnection  Left Brain vs. Right Brain What are some left vs. right differences you’ve heard about? Why would there be a difference? Why just left, or why just right?  Are you left-brained or right-brained? Is the dancer spinning clockwise, or counter-clockwise? Counter-Clockwise Clockwise LEFT BRAIN FUNCTIONS RIGHT BRAIN FUNCTIONS uses logic uses feeling detail oriented “big picture” oriented facts rule imagination rules words and language symbols and images present and past present and future math and science philosophy & religion can comprehend can “get it” (i.e. meaning) knowing believes acknowledges appreciates order/pattern perception spatial perception knows object name knows object function reality based fantasy based forms strategies presents possibilities practical impetuous safe risk taking Left vs. Right brain in pop psychology!  What about ACTUAL asymmetry? The brain does many things as a big unit (for example, attention). But there’s also functional specialization. Examples of hemispheric differences: language (more left) spatial skills (more right). Note: this is not not absolute…handedness and multilingualism can affect this! How can we actually test for hemispheric differences? Measure sulci and gyri (anatomical) Test brain damaged individuals (functional) Brain imaging (functional) Anatomical Asymmetry Language and Spatial Reasoning Impairs verbal Impairs visuospatial skills not spatial skills not verbal skills  Communication across hemispheres Commissures (or commissural fibers) – white matter tracts that extend from one hemisphere to the other. Corpus Callosum – the largest (but not only) commissure. Lateralization and Visual Hemifields Sensory and Motor Function Eliminating Communication: Split-Brain Patients Individuals with severed connections between the right and left hemispheres. Information cannot cross over to the verbal left hemisphere! What do you think will happen if the subject is asked what he sees?  The plot thickens… Suppose in the same individual you present the spoon in his LEFT visual field. He claims he sees nothing. Next we lay out a bunch of objects on the table, including a spoon. We then tell him to reach out and grab one of the objects. What happens? Why would he reach for the spoon, if he can’t tell you he saw a spoon?  The Wada Test Inject sodium amobarbitol (a barbiturate) into an awake patient’s carotid artery, the brain’s major blood supply. Inject on one side, not the other, resulting in a reversible lesion of one hemisphere. Not common these days – invasive. Dr. Juhn Wada Lateralized language function Note: In this figure it appears that Wernicke’s area is in the right hemisphere, however, this is just the terminology for the auditory regions in the superior temporal lobe and can be somewhat misleading. Remember that Wernicke’s area is generally in the left temporal lobe. In some left-handed individuals it can be in both right and left temporal lobe.  Brain Plasticity and Laterality Holloway and colleagues (2000) investigated sensorimotor function in hemispherectomy patients. Brain may “reorganize” itself when damaged, overcoming lateralization of function.  Case studies (A.B. vs L.P.) A.B. Damage to the posterior part of the left temporal lobe Difficulties in reading, speaking and remembering words L.P. Similar injury Trouble recognizing faces, and drawing pictures