By Darold Treffert, MD
Questions are raised continually as to what are the differences in brain mechanisms, if any, between (a) prodigies with certain musical or mathematical skills, for example; (b) persons with savant syndrome with similar skills and abilities and (c) the rest of us who function quite normally overall but lack some spectacular area of expertise. The most obvious difference is, of course, that savants, by definition, have their special skill or skills in spite of some basic mental disability, generally with low IQ scores overall, while prodigies are persons also with special skills or abilities but without such mental disabilities who generally function at a normal or very high level overall and whose IQ scores generally reflect that level of function.
Mauro Pesenti and coworkers in Belgium and France, using PET imaging, sought to study brain mechanisms between a German calculating prodigy (Rudiger Gamm), and normal control subjects as they perform mental calculations. Two reports in the January, 2001 issue of Nature Neuroscience summarize those studies. Brian Butterworth titles his summary “What Makes a Prodigy,” and Mauro Pesenti titles his article “Mental Calculation in a prodigy is sustained by right prefrontal and medial temporal areas.” Butterworth points out that “Gamm is remarkable in that he is able, for example, to calculate 9th powers and 5th roots with great accuracy, and he can find the quotient of 2 primes to 60 decimal places. He calls Gamm the ‘expert’ and the control group ‘non-experts.’ Several important findings emerged. When doing calculations in a typical manner, both the expert and non-expert showed calculation processes activated in the brain bilaterally but with a clear left-sided predominance in a number of specific brain areas which Pesenti lists in detail. When Gamm did the more complex calculations so accurately and quickly however, compared to controls, he ‘recruited’ a system of brain areas implicated in episodic memory including right medial frontal and parahippocampal areas, and utilizes as well a unique method of exploiting the unlimited storage capacity of long-term memory to maintain the sequence of steps and intermediate results needed for these more complex calculations whereas controls, like most of us, relied on more typical very limited span of short-term working memory. The expert here seemed to develop a long term episodic memory by borrowing from other areas of long term memory, just as a computer extends the capacity of RAM by using swap space on the hard drive to create a larger ‘virtual’ memory,’ and recruited much of that from right sided structures.
The article is of interest for several reasons. It compares PET images of this expert prodigy with those of non-expert calculators and points out the unique brain mechanisms in the expert when doing his special skill, providing some neural insights into at least this form or prodigy function. But of interest to savant syndrome, perhaps, is the fact that when doing these special skills, the prodigy is relying on some right brain capacities, and some special memory ‘recruitment.’ It would be interesting, of course, to compare the prodigy neural function with the neural function of savants doing the same tasks, to see if these same areas are involved, or recruited. I found this article of particular interest because of the right-brain nature of special skills in savants as pointed out elsewhere on this site (here and here), and because of the special ‘unconscious’ or ‘memory without reckoning’ which is an integral part of savant syndrome. Could that be the same ‘recruiting’ of unused long term memory space to provide long term working memory seemingly quite unique in this prodigy? Are prodigies and savants linked in that manner?
From this study Butterworth raises the same question scattered throughout our inquiry about the savant: “This study, though focused on a remarkable individual, illuminates the unremarkable as well as the extraordinary skills we all possess.”
Another piece of the puzzle perhaps?
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For more information, please contact:
Darold A. Treffert, MD
St. Agnes Hospital, Fond du Lac, Wisconsin
Clinical Professor, Department of Psychiatry
University of Wisconsin Medical School, Madison
Personal Web site: http://www.daroldtreffert.com