Exploring Brain Connectivity of Single-Digit and Double-Digit in Familiar and Unfamiliar Numerals: A Functional MRI Study
Authors: Sukumaran Pariveena , Abd Hamid Aini Ismafairus , Senik Mohd Harizal 
Published: November 2022

Learning and memory are closely related in a way that the ability to learn new information is done through working memory and the retrieval of the learned information is done through long-term memory [1]. Over the years, a keen interest in investigating the functional network and interaction in the brain regions during processing number magnitudes has increased among cognitive neuroscientists [2]. The majority of studies related to brain connectivity, especially on numeral cognition focus on children as these investigations could provide insight into neurodevelopmental performance [3].

In the current study, we aim to explore brain connectivity associated with familiar and unfamiliar numerals of single-digit and double-digit among young adults. Figure 1 demonstrates the conceptual framework of the current study. This is a quantitative experimental design study that uses a combination of cognitive performance assessment and task-based fMRI block design to measure brain connectivity during learning and retrieval of the acquired information. Fifteen healthy young Malaysian adults in the age range of 18-30 years old who meet the inclusion criteria will be recruited via convenience sampling. Participants will be in one group performing two categories of tasks namely familiar (Chinese) and unfamiliar (Arabic) with two conditions each (single-digit and double-digit). A 3-Tesla MRI Philips Achieva (Philips Medical Systems, Best, Netherlands) scanner with a 32-channel SENSE head coil will be used for data acquisition.
Descriptive statistics will be used to summarise the socio-demographic characteristics of subjects. The mean difference in reaction time and accuracy of answers for single and double-digit in familiar and unfamiliar numerals will be analysed using two-way repeated-measures ANOVA and reported. The pre-processing of the fMRI images will be carried out using MATLAB software, Statistical Parametric Mapping 12, and CONN toolbox. The identification and comparison of the brain's functional connectivity will be done using the GIFT toolbox and Statistical Parametric Mapping 12. Results will be reported in the form of figures and tables.

Both familiar and unfamiliar numerals are expected to activate the fronto-parietal-occipital networks by extracting the network from the cognitive-control domain, sub-cortical domain, and visual domain but with different connectivity values. Unfamiliar numerals are anticipated to have higher connectivity values than familiar numerals. Similar findings are expected to double and single digits, whereby higher connectivity values in double digits than in the single digits. The limited studies on functional connectivity show the main regions involved in mathematic processing are the inferior frontal gyrus (IPG), intraparietal sulcus (IPS), and inferior temporal gyrus (ITG) [4]. The outcome of this study would be beneficial as it could provide baseline data to investigate abnormalities of brain connectivity in learning and memory-related to numerical cognition among the young adult population.