By Yuki Agarwala
An 8-year-old boy underwent hemispherectomy, which is the removal or disconnection of one of the two cerebral hemispheres of the brain (Lew, 2014). Following this, he surprisingly developed calendar calculating abilities, meaning he could recognize the exact day of the week that any day would fall on (Treffert, 2013). Another individual, Daniel Tammet, faced a series of epileptic seizures as a child, after which he discovered his extraordinary ability of remembering long strings of numbers, including being able to recite Pi to 22,514 places (Treffert, n.d).
What do you think these two individuals have in common? They both developed exceptional skills after an injury to their brains. This is known as savant syndrome, a rare condition wherein persons with developmental disorders such as autism or other diseases relating to the central nervous systems develop genius abilities. Savant syndrome is known to occur congenitally or after major brain injury. Individuals with the latter condition are known as “acquired savants” (Treffert, 2009).
Interestingly, these outstanding skills are known to only develop in a narrow range of abilities. These include music, usually in the form of piano; art in the form of extremely realistic drawing, painting, and sculpting; calendar calculating, as in determining the day of the week based on calendar dates; mathematics or being able to compute large numbers without having undergone arithmetic training; and spatial or mechanical skills, such as accurately measuring distance or time without instruments and building bicycles from their parts without prior training. (Treffert, 2009)
Most brain injuries resulting in extraordinary skills seem to occur in the left hemisphere of the brain, resulting in the functioning parts of the right hemisphere compensating for those skills by rewiring and establishing new connections between regions (Ahmad, 2012). Left hemisphere dysfunction is often seen in autism, and approximately 50% of savants are known to have some form of autism (Treffert, 2009). There have also been reports of elderly patients with frontotemporal dementia (FTD) developing artistic or musical skills for the first time after their diagnosis. FTD is a condition similar to Alzheimer’s disease but where the degeneration of neurons often only occurs in the frontal lobe. The disease usually affects the left anterior temporal area of the brain. Experiments with twelve patients with FTD who had acquired savant syndrome and a 9-year-old autistic artistic savant showed the same left anterior temporal dysfunction, demonstrating the role of left-brain dysfunction in savant syndrome (Treffert, 2014).
However, cases of sudden savant syndrome have also been reported, whereby individuals without any injury to the central nervous system suddenly had a “Eureka” moment and appeared to spontaneously understand the principles of an area such as music, math, or art. For example, a 28-year-old individual from Israel described the moment where they were sitting in front of a piano in a shopping mall with a few friends and were just trying to figure out the major and minor chords on the piano when suddenly, they felt their musical knowledge come together and were able to play multiple songs perfectly from memory. Despite never having learned musical theory, the individual was able to listen to music, understand which keys produced the melody, and press those keys on the piano to reproduce the same music (Treffert, 2018). Many such cases of sudden savant syndrome have been reported, making scientists question whether such abilities are inherently present in every individual but are normally inaccessible without particular forms of brain impairment.
In experiments, scientists used low-frequency repetitive transcranial magnetic stimulation (rTMS) to inhibit the lateral anterior temporal lobe in individuals without any history of brain damage or savant syndrome. This technique temporarily inhibits neural activity in the targeted part of the cerebral cortex. Lesions in the lateral anterior temporal lobe have been documented in autistic savants and persons with FTD who developed savant skills later in life, as mentioned above. Surprisingly, the temporary application of rTMS in these experiments resulted in superior drawing, proofreading, and numerical skills in some individuals. Although the participants underwent inactive or sham stimulation a week before or after the actual stimulation for comparison purposes, enhanced skills were only observed after the active stimulation. For example, individuals improved their drawing skills and were able to draw more realistic animals from memory. They also improved their proofreading abilities and were better able to recognize the repetition of certain pronouns such as “the” in sentences (Snyder, 2009; Snyder et al., 2003). This intriguing discovery led to a greater understanding of the role of the lateral anterior temporal lobe in savant syndrome, but the causes of sudden savant syndrome are still unknown.
Although the exact mechanisms underlying the savant skills have not been fully recognized, studies have shown that patients become more literal in the immediate period following application of rTMS, and become less accurate in identifying the meanings of idioms. This is consistent with the features of semantic dementia whereby patients have reduced linguistic, facial recognition, sensory abilities due to damage of the left hemisphere (Ding et al., 2020). Scientists speculate that inhibiting the lateral anterior temporal lobe obscures the networks concerned with recognizing details, ultimately resulting in individuals being able to access unprocessed sensory input and view the world on a larger scale. All the cases of savant syndrome described here rely on this ability to read off and reiterate less processed information, which is thought to be possible by inhibiting a portion of the left hemisphere.
Most individuals who developed or were born with savant abilities polished their skills over their lifetime. For example, Leslie Lemke, a savant with music skills, initially only replicated music he had heard once, but over time, he began to improvise and develop his own music or modifications to existing music. Indeed, most savants keep their talents throughout their life, but there was a case reported in 1977, where a child named Nadia had extraordinary artistic skills during childhood but had difficulty with linguistic and communication skills. When she started attending school and was given intensive training with her language development, however, Nadia lost her ability to draw realistically and begun drawing like an infant. This trade-off between training the left brain for communication and losing savant skills has been termed the “Nadia effect”. While this dreaded trade-off between skills is not common, it brings with it the question of education for such children, as many educators are reluctant to proceed with formal education (Treffert, 2013). Deeper research in this area will be crucial to unlocking the science behind savant syndrome and helping educators nurture the talents of savants.
It is intriguing to consider the processes that can give individuals savant skills suddenly, congenitally, or after central nervous system damage. Often, discovering these abilities requires effort on the part of the caretakers of these individuals. As more individuals with such skills have been recognized and scientific techniques have improved, further research has been conducted into the mechanisms of the syndrome, but the intricacies of the condition are still unknown. Conducting research in this area and having a deeper understanding of the syndrome could potentially help educators develop better teaching methods to help such students to develop their talents further rather than suppress them.
References:
Ahmad, S.I. (2012) Neurodegenerative diseases. [Online]. New York, Landes Bioscience. Available from: https://link.springer.com/chapter/10.1007/978-1-4614-0653-2_25#citeas.
Lew, S.M. (2014) Hemispherectomy in the treatment of seizures: a review. Translational Pediatrics. [Online] Available from: doi:10.3978/j.issn.2224-4336.2014.04.01.
Treffert, D.A. (2013) Savant Syndrome: Realities, Myths and Misconceptions. Journal of Autism and Developmental Disorders. [Online] 44 (3), 564–571. Available from: doi:10.1007/s10803-013-1906-8.
Treffert, D. (n.d.) Daniel Tammet. [Online]. Agnesian HealthCare. Available from: http://www.agnesian.com/page/daniel-tammet [Accessed: 17 March 2021].
Treffert, D.A. (2009) The savant syndrome: an extraordinary condition. A synopsis: past, present, future. Philosophical Transactions of the Royal Society B: Biological Sciences. [Online] 364 (1522), 1351–1357. Available from: doi:10.1098/rstb.2008.0326.
Treffert, D.A. (2014) Accidental Genius. Scientific American. [Online]. 311 (2) pp.52–57. Available from: http://www.jstor.org/stable/2604021 [Accessed: 16 March 2021].
Treffert, D.A. (2018) Brain Gain: A Person Can Instantly Blossom into a Savant–and No One Knows Why. Scientific American. [Online]. Available from: https://blogs.scientificamerican.com/observations/brain-gain-a-person-can-instantly-blossom-into-a-savant-and-no-one-knows-why/ [Accessed: 16 March 2021].
Snyder, A. (2009) Explaining and inducing savant skills: privileged access to lower level, less-processed information. Philosophical Transactions of the Royal Society B: Biological Sciences. [Online] 364 (1522), 1399–1405. Available from: doi:10.1098/rstb.2008.0290.
Snyder, A.W., Mulcahy, E., Taylor, J.L., Mitchell, D.J., et al. (2003) Savant-Like Skills Exposed In Normal People By Suppressing The Left Fronto-Temporal Lobe. Journal of Integrative Neuroscience. [Online] 02 (02), 149–158. Available from: doi:10.1142/s0219635203000287.
Ding, J., Chen, K., Liu, H., Huang, L., et al. (2020) A unified neurocognitive model of semantics language social behaviour and face recognition in semantic dementia. Nature Communications. [Online] 11 (1). Available from: doi:10.1038/s41467-020-16089-9.
Imperial Bioscience Review 