Kim Peek’s special abilities started early, around the age of a year and a half. He could read both pages of an open book at once, one page with one eye and the other with the other eye. This style of reading continued until his dead in 2009. His reading comprehension was impressive. He would retain 98 percent of the information he read. Since he spent most of his days in the library with his dad, he quickly made it through thousands of books, encyclopedia and maps. He could read a thick book in an hour and remember just about anything in it. Because he could quickly absorb loads of information and recall it when necessary, his condition made him a living encyclopedia and a walking GPS. He could provide driving directions between almost any two cities in the world. He could also do calendar calculations (“which day was June 15, 1632?”) and remember old baseball scores and a vast amount of musical, historical and political facts. His memory abilities were astounding.
Unlike many individuals with savant syndrome, Kim Peek was not afflicted with autistic spectrum disorder. Though he was strongly introverted, he did not have difficulties with social understanding and communication. The main cause of his remarkable abilities seems to have been the lack of connections between his brain's two hemispheres. An MRI scan revealed an absence of the corpus callosum, the anterior commissure and the hippocampal commissure, the parts of the neurological system that transfer information between hemispheres. In some sense Kim was a natural born split-brain patient…
Since Kim Peek didn't have a corpus callosum or a hippocampal commissure, his brain would have had to develop the abilities to process language in both hemispheres. This, of course, gave him a major advantage in terms of speed-reading and information retention. You might think the same would apply to other hemisphere-specific abilities, such as visual imagery and math, which are primarily left-hemisphere based. However, Kim Peek was unable to "reason his way through" mathematical problems. Despite his brilliant mind, his IQ was 87, significantly below normal. It was also difficult for him to follow directions of certain kinds.
There are several respects in which Kim Peek was not like Gazzaniga and Sperry's split-brain patients. He did not exhibit any symptoms of truly split personality or conflicting desires deriving from separate hemispheres. How did he avoid this split in information integration when information could not cross over the three main connections between the hemispheres?
We know that the brain can also transfer information indirectly through subcortical areas. Normally, it is a relatively small amount of information that is transferred that way. But Kim Peek may have developed additional subcortical connections for information transfer.
Peek's ability to retain large amounts of information may have had something to do with another condition he was afflicted with called macrocephaly. This brain abnormality consists in an excessively large head and a correspondingly huge brain. Kim's head was so heavy that it took several years before he could hold it up on his own.
As a baby the real rain man was diagnosed with mental retardation and the physicians told his parents that he never would be able to read or talk. They recommended sending their little boy to a mental institution and geting on with their lives. Despite the recommendation, Kim’s parents chose to raise him at home. They quickly realized that their little boy with the oversized head had a remarkable brain. Due to his parets' efforts, Kim had the oppotunity to develop his amazing talents. A large head does not equal intelligence or ability to retain information. But it does provide more storage space for someone who is able to process the content of 10,000 books, which was the number of books Peek had read by the time of the his death in 2009.
The new results come from a metaanalysis of the brain imaging data from seven individuals with agenesis of the corpus callosum, using a mathematical tool known as "connectomic analysis." The metaanalysis revealed that while little information got transferred among hemispheres in the patients, there was greater communication between local areas of the brain. This increased local connectivity may explain both the tendency to be obsessed with details and the increased intellectual abilities of people like Kim Peek. Though decreased holistic brain interaction is likely to negatively influence how we understand contextual cues, the increased local connectivity could lead to more thorough and faster processing of factual information, which in turn could increase memory abilities…
While surgical severing of callosal and other commissures normally results in a disconnection syndrome, patients with callosotomy in childhood and individuals born without a corpus callosum do not suffer these consequences, suggesting that the plasticity of the brain in the fetus and small child allows for information transfer that is relevant to agency and action via alternative neural pathways.