Measurement of Spatial and Verbal Working Memory Using N-Back Task by Near-infrared Spectroscopy

: In this study, we created two N-back task tasks — a verbal working memory (VWM) task and a spatial working memory (SWM) task. We compared the reaction with numerical working memory (NWM). In the experiment, we utilized NWM, VWM, and SWM 3- and 1-back tasks. We employed near-infrared spectroscopy to measure the response of oxyhemoglobin during the working memory tasks. In the analysis, we used changes in oxyhemoglobin of NWM, VWM, and SWM, activation frequency, and accuracy rate. The results showed that VWM and SWM performed the same measurement as NWM. We obtained no relationship between the correct answer rate and activation of the prefrontal cortex in the 1-back task, but the activity frequency was low. The 3-back task had a lower correct answer rate than 1-back but a higher activation frequency. It means that moderate difficulty can encourage activation.