The savant syndrome and its possible relationship to epilepsy.

The goal of this chapter is to review the Savant syndrome (SS), characterized by outstanding islands of mental ability in otherwise handicapped individuals. Two forms exist: The congenital and acquired form. Among the many examples of the congenital form are the calendar calculators, who can quickly provide the day of the week for any date in the past. Other examples are the musical savants with perfect pitch and the hyperlexics, who (in one case) can read a page in 8 seconds and recall the text later at a 99% level. Other types of talents and artistic skills can be found, involving 3-D drawing, map memory, poetry, painting, sculpturing, including one savant who could recite without error the value of Pi to 22,514 places. The acquired form refers to the development of outstanding skills after some brain injury or disease, usually involving the left fronto-temporal area. This type of injury seems to inhibit the 'tyranny of the left hemisphere', allowing the right hemisphere to develop the savant skills. One other way to inhibit the left fronto-temporal area is to use transcranial magnetic stimulation in normal subjects and nearly one-half of these subjects can then perform new skills during the stimulation that they could not perform before. This type of finding indicates the potentiality in all of us for the development of savant skills under special circumstances. Explanations of the congenital SS include enhanced local connectivity as a compensation for underconnectivity of long-range fibers, but also weak central coherence, replaced by great attention to details, enhanced perceptual functioning and obsessive pre-occupation with specific interests. Neurodegenerative Diseases, edited by Shamim I. Ahmad.