Chapter 9: Bisected: Hallucinations in the Half Field, and Chapter 10: Delirious Summary and Analysis

In Chapter 9, Sacks discusses hallucinations that occur when only one eye, or one occipital lobe, has been damaged. The result of this damage is called hemianopia. Unlike hallucinations in migraines or epilepsy, hemianopia hallucinations last days or weeks, and are ever changing. Ellen O had surgery to correct her right occipital lobe, and soon after, began seeing afterimages of things up to a week following her initial viewing of them (for example, she saw a flower, and continued to see the flower in her left eye for a week). These soon made way for complex hallucinations involving grotesque faces or cartoon figures. Although they diminished in size, these hallucinations never completely disappeared. Marlene H experienced migraines for years, but her symptoms began to...