Assessing tRNS to the IPS and the dlPFC as an intervention for improving non-verbal number acuity: A single session approach

Mathematical skills are crucial to life in the modern world and having deficits in these abilities is associated with many negative outcomes such as higher risk of health issues and lower income. The intraparietal sulcus (IPS) has been identified as the central hub of numerical cognition, although many brain areas are involved in the different mathematical processes. These include the dorsolateral prefrontal cortex (dlPFC) which also plays a central role in working memory. There have been a limited number of studies which have attempted to improve mathematical ability using transcranial random noise stimulation (tRNS). tRNS has been shown to improve cognitive function, even after a single session, by increasing cortical excitability in targeted brain areas. This study aimed to assess the efficacy of tRNS for improving non-verbal number acuity over a single session using a 2x2x2 repeated measures design. Participants were split into either the frontal lobe or parietal lobe group and received tRNS twice, one week apart, once when genuine tRNS occurred and once when there was sham stimulation. The sample consisted of 39 university students (M age= 21.39, SD= 2.64). Participants’ non-verbal number acuity was measured using a number line estimation task which they completed prior to and post tRNS in each session. Pairwise comparisons revealed that tRNS to the IPS improved accuracy on the number line estimation task after a single session. Contrary to expectations, tRNS to the dlPFC did not improve reaction times on the number line estimation task, although the impact this has on understanding the role of the dlPFC is limited. These results confirm the central role of the IPS in numerical cognition and highlight tRNS as a potential tool to equalise learning environments, particularly for those with difficulties with mathematics, such as maths anxiety, by targeting foundational mathematical abilities.