Cognitive function assessment in young adult based on mental arithmetic trail making and stroop tasks

Abstract

Executive Function (EF) is an important cognitive skill which undergoes three main processes: updating, shifting and inhibition. However, many brain researchers do not look deeper in Functional Connectivity (FC) between brain regions, and connection of EF from other brain areas still remains unclear. In order to determine cortical networks, FC measurement is needed. This study determines the cortico-cortical FC between brain regions using Partial Directed Coherence (PDC) and investigates the Power Spectral Density (PSD) of brain activity while performing cognitive function assessments. 20 young Malaysian adults were asked to perform three tasks/tests: Mental Arithmetic task (updating), Trail Making Test (shifting); Trailing A and B, and Stroop task (inhibition). Electroencephalography machine was used to record brain signals, and the data were analysed using PDC and PSD. Findings showed that in updating, most of the brain area that generated information was from frontal areas: Fp1, Fp2 and F7, based on correct and incorrect answers given by the subject. Results from two trailing showed that for Trailing A, the information mostly was generated from fronto-temporal areas: Fp2, F7 and T3, whereas for Trailing B, the information generated was almost similar to Trailing A, but slightly different in scalp locations: F7, T3 and T4. For inhibition, fronto-temporal area produced the highest number of information sources: Fp1, Fp2 and T4. In receiving the information, all parts of brain region were interconnected for all three processes. For all processes, significantly increased theta band was found at frontal region with 15.32%, while significant decreased of alpha band was found at occipital (30.73%), temporal (29.83%), and parietal (34.91%) areas. Meanwhile, gamma (y) and high-gamma (hy) bands were significantly higher at central (y=35.73%, hy=70.10%), parietal (y=52.00%, hy=84.87%), and occipital (Y=63.74%, hy=74.65%) areas for shifting and inhibition processes. In conclusion, all parts of brain are interconnected for generating and receiving information during EF task and it shows that EF is not dependent on frontal area only.