who has the biggest brain in the world
Brain size The largest brains are those of sperm whales, weighing about 8 kg (18 lb), and killer whales, weighing about 12–15 lb (5.4–6.8 kg). An elephant's brain weighs just over 5 kg (11 lb) and a bottlenose dolphin's 1.5 to 1.7 kg (3.3 to 3.7 lb).
Split-brain In the 1950's, research on people with certain brain injuries made it possible to suspect that the "language center" in the brain was commonly situated in the left hemisphere. One had observed that people with lesions in two specific areas on the left hemisphere lost their ability to talk, for example. Roger Sperry and his colleague pioneered research. In his early work on animal subjects, Sperry made many noteworthy discoveries. The results of these studies over the next thirty years later led to Roger Sperry being awarded the Nobel Prize in Physiology or Medicine in 1981. Sperry received the prize for his discoveries concerning the functional specialization of the cerebral hemispheres. With the help of so-called "split brain" patients, he carried out experiments, and for the first time in history, knowledge about the left and right hemispheres was revealed.[4] In the 1960s Sperry was later joined by Michael Gazzaniga a psychobiology Ph.D. student in his work on split-brain research at Caltech in Pasadena, California. Even though Sperry is considered the founder of split-brain research, Gazzaniga's clear summaries of their collaborative work are consistently cited in psychology texts. In Sperry and Gazzaniga's "The Split Brain in Man" experiment published in Scientific American in 1967 they wanted to explore the extent to which two halves of the human brain were able to function independently and whether or not they had separate and unique abilities. They wanted to examine how perceptual and intellectual skills were affected in someone with a split-brain. At Caltech, Gazzaniga worked with Sperry on the effects of split-brain surgery on perception, vision and other brain functions. The surgery, which was a treatment for severe epilepsy, involved severing the corpus callosum, which carries signals between the left-brain hemisphere, the seat of speech and analytical capacity, and the right-brain hemisphere, which helps recognize visual patterns. At the time this article was written, only ten patients had undergone the surgery to sever their corpus callosum (corpus callosotomy). Four of these patients had consented to participate in Sperry and Gazzaniga's research. After the corpus callosum severing all four participants personality, intelligence, and emotions appeared to be unaffected. The testing done by Sperry and Gazzaniga showed however, the subjects demonstrated unusual mental abilities. The researchers created three types of tests to analyze the range of cognitive capabilities of the split-brain subjects. The first was to test their visual stimulation abilities, the second test was a tactile stimulation situation and the third tested auditory abilities.