lecture 6 from a college level introduction to psychology course taught Fall 2011 by Brian J. Piper, Ph.D. (firstname.lastname@example.org) at Willamette University, focus is on split brain studies by Michael Gazzaniga, sulci, gyri, plasticity
The Brain •The Cerebral Cortex • Our Divided Brain • Right-Left Differences in the Intact Brain
Neuroanatomy OverviewThe cerebral cortex is the intricate fabric of interconnected neural cells that covers the cerebral hemispheres. It is thebody’s ultimate control and information processing center.
Structure of the Cortex Each brain hemisphere is divided into fourlobes that are separated by prominent fissures. These lobes are thefrontal lobe (forehead),parietal lobe (top to rear head), occipital lobe (back head) and temporal lobe (side of head).
Functions of the Cortex The Motor Cortex is the area at the rear of thefrontal lobes that control voluntary movements. The Sensory Cortex (parietal cortex) receivesinformation from skin surface and sense organs.
Sensory Homunculus• This is a representation of the brain space given to each bodily area
Courtesy of V.P. Clark, K. Keill, J. Ma. Maisog, S. Courtney, L.G. Ungerleider, and J.V. Haxby, National Institute of Mental HealthVisual Function The functional MRI scan shows the visual cortex is active as the subject looks at images.
Auditory FunctionThe functional MRI scan shows the auditory cortex is active inpatients who hallucinate.
Language Aphasia is an impairment of language, usually caused by left hemisphere damage either toBroca’s area (impaired speaking) or to Wernicke’s area (impaired understanding).
Specialization & IntegrationBrain activity when hearing, seeing, and speaking words
The Brain’s PlasticityThe brain is sculpted by our genes but also by our experiences. Plasticity refers to the brain’s ability to modify itself after some types of injury or illness.
Phantom Limbs• V.S. Ramachandran has worked with amputees that have pain from their former limb• Foot fetish• Limb reattachments
Our Divided Brain Our brain is divided into two hemispheres.The left hemisphere processes reading, writing, speaking, mathematics, and comprehension skills. In the 1960s, it was termed as the dominant brain.
Splitting the Brain A procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers(mainly those of the corpus callosum) between them. Corpus Callosum Courtesy of Terence Williams, University of Iowa Martin M. Rother
Split Brain Patients of Michael GazzinigaWith the corpus callosum severed, objects (apple)presented in the right visual field can be named. Objects (pencil) in the left visual field cannot.
Try This!Try drawing one shape with your left hand and one with your right hand, simultaneously. BBC
Right-Left Differences in the Intact Brain People with intact brains also show left-right hemispheric differences in mental abilities. A number of brain scan studies show normal individuals engage their right brain whencompleting a perceptual task and their left brain when carrying out a linguistic task.
“Only left-handers are in their right mind.” Handedness Right LeftLanguage LeftCenter 95% Right 5%
Left-handers are more likely to have their language center in their right cortex Handedness Right LeftLanguage LeftCenter 95% 70% Right 5% 30%
Phineas Gage (1823-1860)• An accident resulted in severe damage to his left-frontal lobe.• He survived but “was no longer Gage”• Records are sparse but he may have adapted.
Is this appropriate?• http://www.youtube.com/watch?v=PFJPtVRlI6• Anterior commissure: the anterior (frontal) part of the corpus collosum
Animal Research• Reduce #• Reduce discomfort• Use alternatives
4.• A researcher conducts a study on how viewing sexually explicit material influences attitudes towards women. Participants are assigned to groups and then complete a survey about their attitudes. – Independent variable: – Dependent variable: – Design:
5.• A researcher gives a survey to all of his friends. – Type of research? – Problem(s)?