Transcranial direct current stimulation of the posterior parietal cortex modulates arithmetic learning

Abstract

The successful acquisition of arithmetic skills is an essential step in the development of mathematical competencies and has been associated with neural activity in the left posterior parietal cortex (PPC). It is unclear, however, whether this brain region plays a causal role in arithmetic skill acquisition and whether arithmetic learning can be modulated by means of non-invasive brain stimulation of this key region. In the present study we addressed these questions by applying transcranial direct current stimulation (tDCS) over the left PPC during a short-term training that simulates the typical path of arithmetic skill acquisition (specifically the transition from effortful procedural to memory-based problem-solving strategies). Sixty participants received either anodal, cathodal or sham tDCS while practising complex multiplication and subtraction problems. The stability of the stimulation-induced learning effects was assessed in a follow-up test 24 h after the training. Learning progress was modulated by tDCS. Cathodal tDCS (compared with sham) decreased learning rates during training and resulted in poorer performance which lasted over 24 h after stimulation. Anodal tDCS showed an operation-specific improvement for subtraction learning. Our findings extend previous studies by demonstrating that the left PPC is causally involved in arithmetic learning (and not only in arithmetic performance) and that even a short-term tDCS application can modulate the success of arithmetic knowledge acquisition. Moreover, our finding of operation-specific anodal stimulation effects suggests that the enhancing effects of tDCS on learning can selectively affect just one of several cognitive processes mediated by the stimulated area. AbstractThe successful acquisition of arithmetic skills is an essential step in the development of mathematical competencies and has been associated with neural activity in the left posterior parietal cortex (PPC). It is unclear, however, whether this brain region plays a causal role in arithmetic skill acquisition and whether arithmetic learning can be modulated by means of non-invasive brain stimulation of this key region. In the present study we addressed these questions by applying transcranial direct current stimulation (tDCS)over the left PPC during a short-term training that simulates the typical path of arithmetic skill acquisition (specifically the transition from effortful procedural to memory-based problem-solving strategies). Sixty participants received either anodal, cathodal, or sham tDCS while practicing complex multiplication and subtraction problems. The stability of the stimulation-induced learning effects was assessed in a follow-up test 24 hours after the training. We found that the learning progress was modulated by tDCS. Cathodal tDCS (compared to sham) decreased learning rates during training and resulted in poorer performance which lasted over 24 hours after stimulation. Anodal tDCS showed an operation-specific improvement for subtraction learning. Our findings ex...

Neurocognitive Effects of Transcranial Direct Current Stimulation in Arithmetic Learning and Performance: A Simultaneous tDCS-fMRI Study

“…Based on our previous studies [13,16,17], we used a tDCS protocol with anodal stimulation of left parietal and cathodal stimulation of right prefrontal areas. We used the same electrode configuration for the active and sham stimulation.…”

“…We used the same electrode configuration for the active and sham stimulation. The anode (5*7cm) was centred over left parietal electrodes CP5 and P5, which was in proximity of IPS and AG [13,16,17,26]. The cathode (5*10 cm) was positioned over right prefrontal areas placing the electrode supraorbitally (between Fpz and AF8).…”

“…In the arithmetic domain, first studies have demonstrated that tDCS can affect arithmetic performance and learning [13][14][15][16]. However, the observed effects strongly depended on the cognitive processes involved in the arithmetic operation as well as the placement of the tDCS electrodes.…”

“…For solving simple arithmetic problems (which is typically done by fact retrieval), in contrast, the same stimulation had detrimental effects. In addition, it was recently found that anodal stimulation of the parietal cortex led to better arithmetic fact learning of subtraction problems, whereas cathodal stimulation led to an impairment in learning [16].…”

The obligatory activation of practiced complex multiplication facts and what it tells us about models of arithmetic processing

“…Much of this research has focused on examining working memory involvement (e.g., Imbo & LeFevre, 2010;Tronsky, 2005), strategies used by typical (skilled adults) and atypical (e.g., math precocious/disabled students, calculating prodigies) populations (e.g., Geary, Hoard, ByrdCraven, & DeSoto, 2004;Hoard, Geary, Byrd-Craven, & Nugent, 2008;Pesenti, Seron, Samson, & Duroux, 1999), and brain areas recruited during the learning and processing of complex arithmetic problems (e.g., Grabner, Rütsche, Ruff, & Hauser, 2015;Ischebeck, Zamarian, Egger, Schocke, & Delazer, 2007). To date, there have not been any investigations of complex arithmetic processing using a number-matching task.…”