Roger Wolcott Sperry - Nobel Prize

Nobel Prize

For main article on Lateralization of Brain Function, see Lateralization of brain function.

Before Sperry's experiments, Jacob Weldon Spence did some research and the evidence seemed to indicate that areas of the brain were largely undifferentiated and interchangeable. In his early experiments, Sperry showed that the opposite was true: after early development, circuits of the brain are largely hardwired.

In his Nobel-winning work, Sperry and Gazzaniga tested four out of ten patients who had undergone an operation developed in 1940 by William Van Wagenen, a neurosurgeon in Rochester, NY. The surgery, designed to treat epileptics with intractable grand mal seizures, involves severing the corpus callosum, the area of the brain used to transfer signals between the right and left hemispheres. Sperry and his colleagues tested these patients with tasks that were known to be dependent on specific hemispheres of the brain and demonstrated that the two halves of the brain may each contain consciousness. In his words, each hemisphere is

indeed a conscious system in its own right, perceiving, thinking, remembering, reasoning, willing, and emoting, all at a characteristically human level, and . . . both the left and the right hemisphere may be conscious simultaneously in different, even in mutually conflicting, mental experiences that run along in parallel —Roger Wolcott Sperry, 1974

This research contributed greatly to understanding the lateralization of brain function. In 1989, Sperry also received the National Medal of Science. Afterwards in 1993, Sperry received the Lifetime Achievement Award from APA. However, perhaps his greatest prize was his achievement in attaining the Nobel Prize in cooperation with David H. Hubel and Torsten N. Wiesel for Physiology or Medicine.

In addition to his contribution in establishing the lateralized function of the brain, Sperry is also noted for his chemo affinity theory, which has been not only influential in formation of testable hypotheses in how precise neuronal wiring diagram is established in the brain, but the hypothesis itself has been verified by numerous experiments.

"The cells and fibers of the brain must carry some kind of individual identification tags, presumably cytochemical in nature, by which they are distinguished one from another almost, in many regions, to the level of the single neurons" —Roger Wolcott Sperry

In the words of a 2009 review article in Science magazine: "He suggested that gradients of such identification tags on retinal neurons and on the target cells in the brain coordinately guide the orderly projection of millions of developing retinal axons. This idea was supported by the identification and genetic analysis of axon guidance molecules, including those that direct development of the vertebrate visual system." This was confirmed in the seventies by Marshall W. Nirenberg's work on chick retinas and later on Drosophila melanogaster larvae.

The experiments conducted by Sperry focused on four major ideas which were also called “turnarounds” that were equipotentiality, split brain studies, nerve regeneration and plasticity, and psychology of the consciousness.