In Search of the Savant Within Us Using rTMS

Darold Treffert MD

The most far-reaching implication of savant syndrome is that, perhaps, some of those remarkable savant abilities, and unique memory capacities, reside, to greater or lesser degree, within us all. The emergence of such buried skills in some persons (so-called “acquired savants”) following brain injury or disease especially raises that important question. Dr. Bruce Miller’s work (described elsewhere on this site) in which there is the emergence of new savant skills in normal, previously non-disabled older adults, as a particular form of brain disease (frontotemporal dementia FTD) progresses, in fact demonstrates that phenomenon through a brain plasticity process named “paradoxical functional facilitation.” I address my views of these possibilites on the “Is there a little ‘Rain Man’ in each of Us” portion of this site.

In an article entitled “Turn Off, Tune In” in New Scientist, October, 1999 Rita Carter summarizes some further speculation on hidden savant potential within us all. One of the theories explored there is that of Drs. Allan Snyder and John Mitchell in which they propose that the lower level cognitive and information processing mechanisms that underpin savant skills reside still in each of us. However because of the interference from higher level cognitive and information processing mechanisms which most of us have come to rely upon, we are unable to access these still present, but buried, lower level savant mechanisms. Ms. Carter describes these lower level mechanisms as being “swamped by more sophisticated conceptual cognition.”

Three Australian researchers have now attempted to document such buried mechanisms in normal persons using repetitive transcranial magnetic stimulation (rTMS) to interfere with normal cortical functioning while searching for the presence of, or enhancement of, savant-like skills and mental processes. rTMS is being used increasingly as a noninvasive CNS investigative and clinical tool including use as an alternative to electro-convulsive treatment (ECT) in certain psychiatric conditions.

The carefully designed, and meticulously carried out, research appears in an Honours Thesis of Tracy Morrell in a joint project between the University of South Australia, Flinders University and Adelaide University. The project is entitled “Investigation of latent savant skills using transcranial magnetic stimulation” and the authors are Morrell, T.L.; Young, R.L. and Ridding, M.C.

These investigators test the Snyder and Mitchell hypothesis that savants have brain damage that adversely affects higher level processes allowing them access to (and limitation to) latent talents. By using rTMS to limit, on a very temporary basis, higher level processes in normal persons. it was anticipated that there would be significant improvement, temporarily, in talents that mediate savant activities such as perfect pitch, eidetic imagery, mechanical reasoning, reading ability and memory along with unmasking of latent abilities in tasks such as calendar calculating, memory, music, integer calculating, reading and artistic abilities. Correspondingly, as the rTMS disrupts on a temporary basis higher order processing, there should be deterioration in performance on tasks, such as short term memory, that rely on such higher level circuitry. The left fronto-temporal area was chosen as the experimental area because damage to this area has been correlated with the emergence of savant like skills in the work of Dr. Miller and others.

Seventeen volunteer subjects, eight female and nine male, between the ages of 20 and 45 were recruited for the study. A wide variety of standard psychological tests and tasks specifically designed to test savant skills and abilities were used which are described in great detail in the thesis. rTMS was used in these subjects to test the general hypothesis that temporary disruption of the left fronto-temporal lobe brain function would enable developmentally normal persons to access mechanisms that might permit the emergence of savant like skills in tasks such as memory, calendar calculating, artistic ability, linguistic representation and mathematical ability.

In the study one participant performed as expected across all tasks. One other participant performed as expected on all but one task. A number of participants performed as predicted in some but not all of the tasks. From this particular study the researchers conclude: “This suggests that contrary to Snyder and Mitchell’s hypothesis, these mechanisms are not accessible to everyone and individuals may differ in either their ability to access these mechanisms or even whether they possess such a mechanism. It is proposed here that such differences may be due to variables such as hereditability, sex, age and/or opportunity. These findings suggest that these skills may be limited to a small percentage of the ‘normal’ population just as they appear to be in the disabled population.” In short, savant capabilities, as measured by this study using rTMS and specific test instruments and tasks, may exist in some, but not all, of us.

The paper proposes further research using rTMS with a number of experimental refinements including attention to genetic predisposition toward talent (family histories); sex differences, younger participants, varied location of cortical stimulation and use of more recently available, more powerful magnetic stimulators.

Unraveling the mystery the savant presents in understanding and explaining such extraordinary brain function in some areas of functioning, along with severe disability in other areas of functioning, will require a variety of research directions and modalities. rTMS is a promising noninvasive method of providing cortical stimulation, as used in this research project, to study brain circuitry and response. More precise neuropsychological (NP) test batteries using tasks and modalities more tailored to special savant abilities, and memory, will be another source of data. And newer functional imaging studies such as SPECT or PET, correlated with and superimposed upon CT and MRI findings as can be done now, is yet another productive technique. This rTMS study helps in moving us beyond merely describing the savant, toward more fully explaining him and her, and exploring the remarkable insights they can provide in better understanding overall brain function, and brain potential.

This rTMS study is very detailed and enlightening. It is only summarized in a brief form here. Beyond description of the study itself, the thesis provides an excellent overall review of savant research to date, a synopsis of rTMS and its application to central nervous system study, and provides a rich resource for up to date references in both these areas.

 Update: March 19, 2004

The TMS “thinking cap” and savant skills

The first formal published study on the use of TMS (Trans-magnetic Stimulation) to perhaps uncover latent savant skills in normal persons has now been published. Dr. Allan Snyder and coworkers at the Centre for the Mind in Sydney, Australia used TMS to suppress activity in the left fronto-temporal area of the brain of 11 male volunteers in order to measure changes in performance on tasks of drawing and proofreading. Their paper titled “Savant-like skills exposed in normal people by suppressing the left fronto-temporal lobe” appeared in the Journal of Integrative Neuroscience (Volume 2, Number 2, 149-158, 2003).

In their study participants were exposed to both placebo stimulation and real stimulation (15 minute exposure at 0.5 Hz or 1 Hz) in two experimental sessions separated by approximately one week. Four tasks were used: drawing an animal; reproducing (drawing) an image of a female face on a computer screen; proofreading ten proverbs, two of which included duplicated words; and proofreading a paragraph with two duplicated word errors.

According to the investigators, TMS did not lead to any systematic improvement in naturalistic drawing ability. However TMS did lead to “a major change in the schema or convention of the drawings in four of the eleven participants.” Two of the four persons in whom changes in drawing style were evident produced ‘after’ drawings of dogs that were more ‘complex’ than before stimulation, and one person produced drawings of horses “more life-like, even flamboyant” after stimulation compared with TMS. A fourth person showed changes in ability to draw faces post-TMS highlighting certain features, particularly the eyes. The article contains illustrations of those changes so the reader can draw his or her own conclusions about those differences before and after TMS.

Three of the four “facilitated” participants described some altered perceptions after stimulation including being “more alert” and “conscious of detail” for example. Two participants displayed a noticeable improvement in their ability to recognize duplicated words (proofreading) in text following TMS application.

From these findings the authors conclude: “low frequency TMS of the left-temporal love did not lead to a systematic improvement of artistic performance. But, it did cause major changes in the scheme or convention of drawings for four of 11 participants, two of whom significantly improved at proofreading. We emphasize that these changes are due to the inhibiting influence of low frequency TMS. They are due to turning off part of the brain, not exciting it (providing) empirical evidence for the hypothesis that savant-like skills can be facilitated in a healthy individual by suppressing part of the brain with TMS.”

Reference
Morrell, T. L., Young, R.L. and Ridding, M.C. (2000) Investigation of latent savant skills using trancranial magnetic stimulation Unpublished Honours thesis, University of South Australia.

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