The Divided Brain Chapter 2, Lecture 6 “We have glimpsed the truth of this chapter’s overriding principle: Everything psychological is simultaneously biological.” - David Myers

“Most of the body’s paired organs – kidneys, lungs, breasts – perform identical functions, providing a backup system should one side fail. Not so the brain’s two halves, which can simultaneously carry out different functions with minimal duplication of effort. The result is a biologically odd but smart couple, each seemingly with a mind of its own.” - David Myers

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 Martin M. Rother Courtesy of Terence Williams, University of Iowa

Split Brain Patients With the corpus callosum severed, objects (apple) presented in the right visual field can be named. Objects (pencil) in the left visual field cannot.

Divided Consciousness

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 when completing a perceptual task and their left brain when carrying out a linguistic task. Let’s look at some case studies of split-brain patients, then create our own!!!

Homework AY Questions – p.58, 81 (10 pts) “To paraphrase cosmologist John Barrow, a brain simple enough to be understood is too simple to produce a mind able to understand it.” - David Myers “From nineteenth-century phrenology to today’s neuroscience, we have come a long way. Yet what is unknown still dwarfs what is known.” - David Myers