Brain activation during a manipulative task and working memory hypothesis

Working memory is an active memory that plays a major role in executing manipulative and cognitive tasks. One of the most important functions of working memory is monitoring one´s own on-going activities to properly execute goal-directed actions. There is some evidence that the dorsolateral prefrontal cortex (DLPFC) can be associated with working memory and it is proposed that the use of the DLPFC decreases as a human develops motor skills. In the present study, we investigated the activation of the DLPFC of the brain in Brodmann´s areas 9 and 46 in drawing tasks to examine whether near-infrared spectroscopy (NIRS) can measure the changes of the DLPFC activation as a human develops motor skills. NIRS can be used to monitor brain activation by measuring changes in the concentration of oxy- and deoxy-hemoglobin (Hb) which are reflected in different spectra in the near-infrared range. Because NIRS is a non-invasive, highly flexible and portable technique, it is very suitable to study brain activation when a human repeatedly performs a manipulative task, and may provide useful information to construct human adaptive mechatronics (HAM). Participants performed a mirror drawing task and a square drawing task using their non-dominant hand. In the mirror drawing task, the participant traced a star shape viewed only in a mirror. The square drawing did not involve a mirror and was expected to be simpler. The change in oxy-Hb concentration decreased as the participant repeated the drawing task in most participants. In conclusion, the activation of DLPFC decreases when a human develops manipulative tasks. Oxy-Hb data measured by NIRS can reflect the brain activity in the development of manipulative skills.