A lot of people claim that they are bad at math and terrible with numbers. But a lot of people also know how to count, or that 2 + 2 = 4 . We take numerical skills like these for granted, but there is a portion of the population that struggle with “simple” numerical tasks like these. In fact, these people take up 5-8% of the population and suffer from a learning disability called dyscalculia, essentially the math version of dyslexia, and struggle to do numerical tasks such as count, compare quantities, tell time, remember arithmetic facts, amongst other magnitude-related tasks (Lewis & Fisher, 2016).
What is Dyscalculia?
A majority of those with dyscalculia are classified as developmental dyscalculia, further abbreviated as DD– an impairment in numerical ability that is first noticed in childhood and can be lifelong. Developmental Dyscalculia is a multi-faceted learning disability and there is great heterogeneity in those who suffer from it. Impairments can be in children’s approximate number system (a nonsymbolic number sense that allows us to compare quantities), in their general magnitude-processing (such as for space, time, and number), and/or in their general cognitive ability (Traff, Olsson et al., 2017). Some children are classified as having secondary DD, when their numerical deficits can be explained entirely by non-numerical impairments, such as attention or short term memory processes (Kaufmann, Mazzocco et al., 2013).
Current approach to treatment
Thus far, the typical approach for mitigating these numerical difficulties is with strategy instruction interventions, where special education instructors teach students strategies for performing numerical tasks (Monei & Pedro, 2017). For example, they could receive explicit practice and feedback counting, in a special way, in order to solve simple arithmetic problems (e.g., 2 + 4 = 6; Powell, Fuchs, Seethaler, Cirino, et al., 2010).
The Future
However, with advances in neuroscientific technology and the optimistic results of using transcranial direct current stimulation (tDCS) to improve performance in multiple cognitive functions: semantic memory (Cerruti & Schleug, 2009), language learning (Floel, Rosser, Michka, Knecht, & Breitenstein, 2008), response inhibition (Jacobson, Javitt, & Lavidor, 2011), and probabilistic learning (Kincses et al. 2004), many have been turning their attention towards these non-invasive brain stimulation methods for solutions to help those with DD.
Although there have been many positive results of using tDCS on cognitive healthy participants on various tasks: number comparison, mental arithmetic (subtraction; Hauser, Rotzer, Grabner, Merillat, & Jancke, 2013), approximate numerical averaging (Brezis, Bronfmna, Jacoby, Lavidor, & Usher, 2016), there are many neuroethical concerns, of some I’ll discuss here, regarding the translation of this research to the clinical population, which is composed mostly of children.
Reservations on Applying to DD population: Neuroethical Concerns
Children with DD often struggle with more than just math. DD has high comorbidity rates (20-60%) with Dyslexia (e.g., Dirks, Spyer, van Lieshout, & de Sonneville, 2008) or Attention Deficient Hyperactivity Disorder (ADHD; Capano, Minden et al., 2008). Thus, there are concerns over tDCS exacerbating the disadvantage experienced by these children.
The main neuroethical concerns of using tDCS on DD children stem from children’s degree of vulnerability to negative consequences. These children already have cognitive impairments that make everyday life and school difficult; the premature application of tDCS treatments for them may interfere with brain development and thus, has the potential of worsening other cognitive functions. Here, I will discuss two main neuroethical concerns: the potential for tDCS treatments to disrupt brain development and the potential for authority figures to coerce children into receiving tDCS:
(1) Developmental interference. The use of tDCS in the treatment of DD would mean repeated stimulation of the parietal cortex of the brain, where the critical area for processing numbers intraparietal sulcus (IPS) is located (e.g., Pinel, Dehaene et al., 2001) during years that are crucial for brain development, especially for the maturation of the prefrontal cortex (PFC), a region of the brain undergoes most of its development during (pre)adolescence and is responsible for complex cognitive processes like planning and decision making.
DD can be diagnosed as early as kindergarten (~ 5 years old) and many children with it start to struggle in elementary school (preadolescence). Throughout these stages of early childhood and preadolescence, the frontal lobe increases in volume (Giedd, Bluementhal et al., 1999). However, it is during preadolescence when we observe substantial increase in volume of the PFC (Gogtay, Giedd, et al., 2004). This is a very sensitive time period to be administering tDCS with a protocol we do not fully understand the long-term consequences of, even for adults.
tDCS could hinder PFC development or encourage abnormal PFC development in these DD children. What’s more, we have already found prefrontal alterations in DD children (Kucian et al, 2006; Ashkenazi, Rosenberg-Lee, et al., 2012), and thus, have the risk of making the abnormalities worse.
By repeatedly stimulating the parietal cortex, and encouraging greater brain activity in that region, we may be decreasing the metabolic consumption of other brain areas like the PFC. The PFC may not receive as much of the energy and nutrition needed for it to undergo its stages of development and maturation.
This is troublesome because PFC is responsible for the allocation of attentional and short term memory resources, which DD children rely on to perform numerical tasks their IPS has a hard time with, and time is needed to learn to use these cognitive resources effectively and for them to strengthen. Underdevelopment of their PFC for their age would continue to exacerbate their poor math performance for their age.
tDCS may also create abnormal connectivities between the PFC and the IPS by inducing abnormal patterns in brain activity in the parietal cortex and interconnected areas. As stronger frontoparietal connectivity helps the development of short term memory (Edin, Macoveanu, et al., 2007) disrupting the creations of said connections could make it even harder for DD children to use cognitive strategies to perform numerical tasks.
If prolonged tDCS treatment does not improve IPS function, we would essentially be taking away their crutch without a functioning replacement leg.
(2) Coercive use. tDCS may be imposed onto children by their parents and/or by private schools, with little legal protection over the child’s autonomy.
From a legal standpoint, minors are incompetent to make reasoned decisions about their welfare (Weithorn, & Campbell, 1982). As such, parents need to make these decisions for them.Parents have the right to control the upbringing of their children, which is protected under the Fourteenth Amendment. This allows parents to impose tDCS treatment even against the child’s will. The only scapegoat would be if imposing such can be classified as child abuse. Circumstances could include those that result in serious physical or emotional harm, and/or the misuse of tDCS (e.g., failing to follow safety precautions).
Another entity that can impose these treatments are private schools. At least in California, private schools function outside the jurisdiction of most state education regulations (California Department of Education, 2018). These private schools may mandate tDCS treatment as part of their (special education) curriculum. While the child (and her parents) can appeal the procedure, courts have been reluctant to interfere with the private school’s decisions (Rabban, 1973).
There are currently no legal regulations against private schools mandating these treatments, and students may need to resort to transferring to another school in order to escape treatment (Jwa, 2019).
The ability to improve the numerical skills of those who suffer from DD has huge societal benefits. Their math learning disability limits their job options and yearly earnings, as well as their contribution to the workforce and society. So far traditional intervention programs require one-on-one attention between the specially trained educator and the students and can take significant amount of hours outside the classroom to get enough deliberate practice and feedback to see improvement. On the other hand, tDCS devices are affordable and for training educators to use them safely and effectively would be a more efficient use of time and resources, especially if it yields faster and longer-lasting improvements. Therefore, research into using tDCS, or a similar transcranial electrical stimulation device, like tRNS, are worth doing.
References
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