Savants’ skills – A short review

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Leandro Castelluccio

(Image taken from: link)

According to the “Centre for the Mind” (n.d.), a group of researchers at University Hall, in Sydney, Australia, dedicated to research on creativity and savant-like abilities, such as those displayed in some forms of autism, the expression “savants” is a term that refers to extremely rare individuals who, although often severely brain impaired, can still display astonishing excellence in specific areas, including drawing, memory, music, calendar calculations, and arithmetic. According to Kelleher and Bear (2008), autism is a complex genetic disorder, and recent evidence suggests that some molecular defects present in the syndrome may interfere with the mechanisms of synaptic protein synthesis. These authors propose that this kind of synaptic protein synthesis may represent one possible pathway leading to autistic phenotypes, including cognitive impairment and savant abilities.

Takahata and Kato (2008) classified current cognitive models of Savant Syndrome into 3 categories: (1) a hypermnesic model that suggests that savant skills develop from existing or dormant cognitive functions such as memory; (2) a paradoxical functional facilitation model that offers possible explanations about how pathological states in the brain lead to development of prodigious skills and (3) autistic models, including those based on weak central coherence theory that focus on how savant skills emerge from an autistic brain, where underconnectivity exists, in which there is a disruption of long-range connectivity and the relative intact or even more enhanced local connectivity. The authors conclude that all the models have certain advantages and shortcomings.

Savants’ privileged access to lower levels of sensory information, prior to it being integrated into a holistic picture, could be particularly hypothesized for explaining their abilities (Snyder, Bahramali, Hawker, & Mitchell, 2006). On the other hand, Snyder, Bossomaier and Mitchell (2004) conceptualize autism as a state of retarded concept formation, in which there is access to object attributes in a detailed manner. The brain favors neural networks for concepts as a computational strategy, inhibiting the access to this lower level information (Bossomaier & Snyder, 2004). According to these authors, it is expected then that penalties should be found for introducing, for example, absolute pitch (low-level and detailed) into the conceptual areas of the left hemisphere. They review some evidence indicating that this might be the case, arguing that if we take away focus on the details, we can learn higher-level structures. Snyder et al. (2004) predict the possibility of accessing non-conscious information by artificially disinhibiting (turning off) the inhibiting networks associated with concept formation, using TMS (transcranial magnetic stimulation). This would be the principle under which TMS could induce savant like skills.

TMS implies the use of brief magnetic pulses applied via an induction coil over the cortex, the pulses can randomly excites both excitatory and inhibitory neurons within its field, which results in transient disruption of processing in a reasonably focal area, creating a sort of “virtual lesion”, allowing researchers for example to determine whether specific brain areas play a causal role in certain types of processing. Which neurons are affected is a function of coil position or orientation, among other factors. Following Huang, Edwards, Rounis, Bhatia and Rothwell (2005), the effects on synaptic plasticity reported using TMS are often weak, highly variable between individuals, and rarely last longer than 30 min, although it has been known for example that repeated electrical stimulation of neural pathways can lead to long-term potentiation in hippocampal slices for example. It all seems to depend on the particular technique used. These authors describe a method of conditioning the human motor cortex using repetitive transcranial magnetic stimulation(rTMS) that produces a controllable, consistent, long-lasting, and powerful effect on motor cortex physiology and behavior after an application period of 20-190seconds. Apparently the scope of the technique could go beyond research alone. As Loo and Mitchell (2005) point out, there is growing interest in extending the use of rTMS beyond research centers to the widespread clinical treatment of depression for example, showing that there is a fairly consistent statistical evidence for the superiority of rTMS over sham control, although the degree of clinical improvement is not large, however, evidence suggests greater efficacy with longer treatment courses. According to the authors, studies have varied greatly in approaches to rTMS stimulation (with respect to stimulation site, stimulus parameters, etc.) with little empirical evidence to inform on the relative merits of these approaches, concluding that current data nevertheless supports positive outcomes for rTMS.

It seems that there is evidence for the prediction of using TMS to induce savant-like abilities. In a study by Chi and Snyder (2011) on inducing insight using TMS, only 20% of participants solved an insight problem with sham stimulation (control condition), whereas 3 times as many participants did so with cathodal stimulation (decreased excitability) of the left anterior temporal lobe (ATL) together with anodal stimulation (increased excitability) of the right ATL. Also, Snyder et al. (2003) used low frequency magnetic pulses into the left fronto-temporal lobe, showing significant stylistic changes in drawing in 4 of 11 participants. Some of these participants also displayed enhanced proofreading ability. So this would support the thesis mentioned by Takahata and Kato (2008) that enhanced local connectivity results in the specialization and facilitation of low-level cognitive processing. For these authors disruption of connectivity between the prefrontal cortex and other regions is of particular importance, because the prefrontal region shows the most influential inhibitory control on other cortical areas, so this mechanisms would explain the emergence of savant ability.

Additional evidence for this can be found in in experiments such as the one by Gallate, Ellwood and Snyder (2009), whotried to reduce false memories by temporarily inhibiting the left anterior temporal lobe (a site implicated in semantic memory and conceptual labeling), using low frequency magnetic pulse stimulation. Participants in the TMS group had 36% fewer false memories than they had with sham stimulation and intact veridical memory. This is comparable to the improvement that people with autism and semantic dementia show over “normal” individuals, like in certain pathologies, including anterior temporal lobe dementia, conditions that can lead to literal recall and thus greater resistance to false memories. A similar later experiment by Chi, Fregni and Snyder (2010)attempted to improve visual memory with non-invasive brain stimulation to imitate the performance of people who have a more literal cognitive style. The experiment was conducted by applying 13 min of bilateral transcranial direct current stimulation (tDCS) to the anterior temporal lobes. Results indicated that only participants who received left cathodal stimulation (decrease in excitability) together with right anodal stimulation (increase in excitability) showed an improvement in visual memory up to 110 percent, similarly to the advantage people with autism have.

Another savant skill is numerosity. Oliver Sacks observed autistic twins for example, who instantly guessed the exact number of matchsticks that had just fallen on the floor (Snyder et al., 2006). These authors conducted a study in which they simulated this ability in 12 normal participants by inhibiting the left ATL with rTMS. Results show that 10 participants improved their ability to accurately guess the number of discrete items immediately following rTMS. The authors argue that the probability of as many as 8 out of 12 people doing best just after rTMS and not after sham stimulation (control condition) by chance alone is less than one in one thousand, indicating a relevant effect.

An example of the stimulus material used by Snyder et al. (2006)

All these experiments involved affecting the left temporal lobe area and is worth noting that people with the acquired form of Savant Syndrome develop outstanding skills after brain injury or disease, usually involving the left fronto-temporal area (Hughes, 2010). There could be a relation between this and the notion of left vs right brain function (left being more analytical and right being more intuitive, although these supposed differences have been mitigated and restructured by empirical evidence with time). As Hughes (2010) points out such type of injury seems to inhibit the “tyranny of the left hemisphere,” allowing the right hemisphere to develop the savant skills. Following Chi and Snyder (2011), it is considered thatonce we have learned to solve problems by one method, we often have difficulties in generating solutions involving a different kind of insight, yet people with brain lesions are sometimes more resistant to this so-called mental set effect. These authors tested whether this mental set effect can be reduced by non-invasive brain stimulation. Only 20% of participants solved an insight problem with sham stimulation (control), whereas 3 times as many participants did so (p = 0.011) with cathodal stimulation (decreased excitability) of the left ATL temporal lobes together with anodal stimulation (increased excitability) of the right ATL. Their findings would be consistent with the theory that inhibition to the left ATL can lead to a cognitive style that is less influenced by mental templates and that the right ATL may be associated with insight or novel meaning. But this could also be due to the access to literal, “low level”-information, instead of relying in certain schemata that does not facilitate a different approach when it is needed. The authors suggest that further studies including neurophysiological imaging are needed to elucidate the specific mechanisms leading to this kind of enhancement.

Following Snyder et al. (2006) study on inducing numerosity, one could introduce fMRI as an additional instrument to assess brain changes in BOLD responses (Blood-oxygen-level dependent) while performing a task of guessing the number of dots on a screen. This could give us new insights into the mechanism of lower level processing and conceptual information networks. According to what we have discussed above, we would expect areas of the brain associated with lower level processing to be more activated during the task for those participants in the TMS condition. In this scenario, participants would have to undergo rTMS a few minutes before the MRI scan, which implies an off-line TMS technique, where the effects of the magnetic pulses last for a few minutes. We could ask participants to indicate if there are more than 100 or less than 100 dots, for example. We could predict that participants’ bold response will differ according to the condition and expect less activation of conceptual and semantic areas of the brain for those on the rTMS condition. However, which areas will be more activated (since we will be “turning off” inhibiting areas) is debatable. This would be the most significant and interesting aspect to evaluate, which would give us evidence of lower level processing areas within the neocortex, according to our assumptions. This would help us further enhance our understanding of the brain mechanism and processes involved in inducing savant-like skills in normal subjects.

The above would also suggest thatthe astonishing skills of savants might be latent in everyone, butare not normally accessible without a rare form of brain impairment according to Snyder et al. (2003). Following these authors, one view is that savants acquire their peculiar skills like any normal person, through repetitive practice while others suggest savants have more highly developed brains in specific domains, but according to the authors these explanations do not fit well with reports that savant skills can emerge “spontaneously” following an accident or during the onset of fronto-temporal dementia for example, and that these skills do not improve qualitatively with time, even though they may become better articulated. Additionally, savant skills could be considered as largely innate, requiring little or no practice and due to brain impairment, savants have a paradoxical facilitation of information that seems to reside equally within everyone but cannot normally be accessed.

And indeed, the Savant Syndrome is characterized by outstanding islands of mental ability in otherwise handicapped individuals (Hughes, 2010). There appears to be two forms: the congenital one and the acquired form. Among the many examples of the congenital are the calendar calculators, who can quickly provide the day of the week for any date in the past, also musical savants, who have perfect pitch, in addition to hyperlexics, who can read a page in few seconds and recall the text later at a very high percentage accuracy. Other types of talents and artistic skills include three-dimensional drawing, map memory, poetry, painting, and sculpturing (Hughes, 2010).

On the other hand, explanations of congenital Savant Syndrome include enhanced local connectivity as a compensation for underconnectivity of long-range fibers, but also weak central coherence, replaced by great attention to detail, enhanced perceptual functioning, and obsessive preoccupation with specific interests (Hughes, 2010).

It is also evident that brilliant minds have existed which displayed these sorts of abilities, but lacking the impairments associated with Savant Syndrome, which indicate that there might be no need for less functioning in one aspect of the brain, or that there are different mechanisms in which one can arrive to such skills, although some of the mechanisms in savants might be present to certain extent in these kind of individuals. However it is equally true that very often these skillful individuals show some form of decreased interest or ability in other aspects of life, similarly as itis usually observed in individuals with autistic spectrum disorders (ASD), like their impaired integrative cognitive processing such as social cognition or executive function, restricted interest, and compulsive repetition of the same act (Takahata & Kato, 2008). This reminds us of many cases of high functioning autism, like in Asperger’s Syndrome (AS). In a paper by Treffert (2014)realities from myths and misconceptions are sorts out about both Savant Syndrome and ASD. According to the author, low IQ is not necessarily an accompaniment of Savant Syndrome and in some cases IQ can be superior. Also, genius and prodigy exist separate from Savant Syndrome and not all such highly gifted persons have AS for example. The paper also gives emphasizes in separating “autistic-like” symptoms from AS, especially in children, when the savant ability presents itself as hyperlexia (children who read early) or as Einstein syndrome (children who speak late) for example. In those cases the term “outgrowing autism” might be mistakenly applied when in fact the child did not have AS(Treffert, 2014). Neff (2016) points out that although AS as a distinct diagnosis was included in the Diagnostic and Statistical Manual of Mental Disorders(the fourth edition), the DSM-5 now includes it under the umbrella of ASD. As the author mentions, this change was made in an effort to make the diagnosis of ASD more valid and reliable, since AS was not considered distinct enough from ASD to warrant a separate diagnosis. The new DSM puts the syndrome as a developmental disorder that is characterized by two psychopathological domains: persistent deficits in social communication and social interaction, and restrictive and repetitive patterns of behavior, interests, or activities.

Finally, another factor to consider. According to Baron-Cohen (2002), increasing psychological evidence supports the notion thatautism can be an extreme of the normal male profile. As the author mentions, the two dimensions for understanding human sex differences are “empathizing” and “systemizing”. The male brain is defined psychometrically as those individuals in whom systemizing is significantly better than empathizing, and the female brain is defined as the opposite cognitive profile. Using these definitions, autism seems in its structure and forms of behavior as an extreme male brain condition.

Here you can watch some interesting documentaries of some famous cases of Savants and people with Asperger’s Syndrome:

The Boy With The Incredible Brain (link)

The Musical Genius (link)

The Human Camera (link)

The Real Rain Man (link)

References

Baron-Cohen, S. (2002). The extreme male brain theory of autism. Trends in cognitive sciences, 6(6), 248-254.

Bossomaier, T., & Snyder, A. (2004). Absolute pitch accessible to everyone by turning off part of the brain?. Organised Sound, 9(02), 181-189.

Centre for the Mind – Research. (n.d.). Retrieved June 17, 2016, from: http://www.centreforthemind.com/research/tms.cfm

Chi, R. P., Fregni, F., & Snyder, A. W. (2010). Visual memory improved by non-invasive brain stimulation. Brain Research, 1353, 168-175.

Chi, R. P., & Snyder, A. W. (2011). Facilitate insight by non-invasive brain stimulation. PloS one, 6(2), e16655.

Gallate, J., Chi, R., Ellwood, S., & Snyder, A. (2009). Reducing false memories by magnetic pulse stimulation. Neuroscience letters, 449(3), 151-154.

Huang, Y. Z., Edwards, M. J., Rounis, E., Bhatia, K. P., & Rothwell, J. C. (2005). Theta burst stimulation of the human motor cortex. Neuron, 45(2), 201-206.

Hughes, J. R. (2010). A review of Savant Syndrome and its possible relationship to epilepsy. Epilepsy & behavior, 17(2), 147-152.

Kelleher III, R. J., & Bear, M. F. (2008). The autistic neuron: troubled translation?. Cell, 135(3), 401-406.

Loo, C. K., & Mitchell, P. B. (2005). A review of the efficacy of transcranial magnetic stimulation (TMS) treatment for depression, and current and future strategies to optimize efficacy. Journal of affective disorders, 88(3), 255-267.

Neff, M. R. (2016). Asperger’s Syndrome in Adults.

Snyder, A., Bahramali, H., Hawker, T., & Mitchell, D. J. (2006). Savant-like numerosity skills revealed in normal people by magnetic pulses. Perception, 35(6), 837-845.

Snyder, A., Bossomaier, T., & Mitchell, D. J. (2004). Concept formation:’object’attributes dynamically inhibited from conscious awareness. Journal of Integrative Neuroscience, 3(01), 31-46.

Snyder, A. W., Mulcahy, E., Taylor, J. L., Mitchell, D. J., Sachdev, P., & Gandevia, S. C. (2003). Savant-like skills exposed in normal people by suppressing the left fronto-temporal lobe. Journal of integrative neuroscience, 2(02), 149-158.

Takahata, K., & Kato, M. (2008). Neural mechanism underlying autistic savant and acquired savant syndrome. Brain and nerve= Shinkei kenkyu no shinpo, 60(7), 861-869.

Treffert, D. A. (2014). Savant syndrome: Realities, myths and misconceptions. Journal of Autism and Developmental Disorders, 44(3), 564-571.