Transcranial random noise stimulation mitigates increased difficulty in an arithmetic learning task

Abstract

Proficiency in arithmetic learning can be achieved by using a multitude of strategies, the most salient of which are procedural learning (applying a certain set of computations) and rote learning (direct retrieval from long-term memory). Here we investigated the effect of transcranial random noise stimulation (tRNS), a non-invasive brain stimulation method previously shown to enhance cognitive training, on both types of learning in a 5-day sham-controlled training study, under two conditions of task difficulty, defined in terms of item repetition. On the basis of previous research implicating the prefrontal and posterior parietal cortex in early and late stages of arithmetic learning, respectively, sham-controlled tRNS was applied to bilateral prefrontal cortex for the first 3 days and to the posterior parietal cortex for the last 2 days of a 5-day training phase. The training involved learning to solve arithmetic problems by applying a calculation algorithm; both trained and untrained problems were used in a brief testing phase at the end of the training phase. Task difficulty was manipulated between subjects by using either a large (“easy” condition) or a small (“difficult” condition) number of repetition of problems during training. Measures of attention and working memory were acquired before and after the training phase. As compared to sham, participants in the tRNS condition displayed faster reaction times and increased learning rate during the training phase; as well as faster reaction times for both trained and untrained (new) problems, which indicated a transfer effect after the end of training. All stimulation effects reached significance only in the “difficult” condition when number of repetition was lower. There were no transfer effects of tRNS on attention or working memory. The results support the view that tRNS can produce specific facilitative effects on numerical cognition – specifically, on arithmetic learning. They also highlight the importance of task difficulty in the neuromodulation of learning, which in the current study due to the manipulation of item repetition might have being mediated by the memory system.

Transcranial random noise stimulation and cognitive training to improve learning and cognition of the atypically developing brain: A pilot study

“…We also recorded their experiences of tRNS using a questionnaire at the end of the study. Based on previous studies on young healthy adults 9, 13, 15 , we hypothesized that compared to training alone, tRNS during cognitive training would (1) improve the learning of children with MLD and (2) increase transfer effects to a real-life task.

Figure 1Transcranial random noise stimulation coupled with cognitive training to improve learning of children with mathematical learning disabilities at school ( a ) Illustration of a child moving from side-to-side to map a number on a number line while receiving transcranial random noise stimulation from a wireless brain stimulator. Response was registered for each trial when both hands were raised.

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Adaptive Plasticity in the Healthy Language Network: Implications for Language Recovery after Stroke

“…In summary, most of the previous studies applied tACS and tRNS in the motor, visual, or auditory system to directly modulate cortical rhythms, but some studies also reported modulation of higher cognitive functions after tACS and otDCS (reviewed in [79–81]) or, more recently, tRNS [97, 98]. …”

Cognitive Enhancement of Numerical and Arithmetic Capabilities: a Mini-Review of Available Transcranial Electric Stimulation Studies

“…In addition, hemodynamic recordings captured short-term and long-term physiological tRNS effects. More recently, an interesting combination of prefrontal tRNS on days 1-3 and parietal tRNS on days 4-5 was observed to improve performance in difficult math problems and accuracy in new and easy problems (Popescu et al 2016). But also targeting the left parietal cortex with 1.5 mA in a single-day training study on multiplication and subtraction facts, polarity-specific and operationspecific subtraction learning improvements were found and performance differences were sustained in a 24-h follow-up .…”

“…In cognitive tasks, mixed results were obtained and some studies report on the lack of performance modulations in working memory tasks (Mulquiney et al 2011;Holmes et al 2016). However, numerous studies also report on effective performance and learning modulations by tRNS in numerical tasks and trainings (Cappelletti et al 2013;Snowball et al 2013;Pasqualotto 2016;Popescu et al 2016). Little direct behavioral outcome comparisons between the two techniques exist to date.…”

“…An interesting concept is the modulation of distinct learning phases over different cortex regions as implemented by Popescu et al (2016). Future research needs to validate this approach by individualized transcranial stimulation or by comparing different configuration changes directly (e.g., switching from prefrontal to parietal stimulation after 2, 3, or 4 days).…”