Comparison of cortical activation in an upper limb added-purpose task versus a single-purpose task: a near-infrared spectroscopy study

[Purpose] The purpose of this study was to compare prefrontal activations during an added-purpose task with those during a single-purpose task using functional near-infrared spectroscopy. [Subjects] Six healthy right-handed adults were included in this study. [Methods] The participants were instructed to complete both added-purpose and single-purpose activities separately with each hand. The near-infrared spectroscopy probes were placed on the scalp overlying the prefrontal cortex, according to the International 10–20 system (Fz). Changes in the oxygenated hemoglobin and deoxygenated hemoglobin concentrations in the prefrontal cortex were measured during performance of the activities. We then compared the number of activation channels with significant increase in oxygenated hemoglobin, during added-purpose activity to single-purpose activity using both hands separately. [Results] A greater number of widespread activations were observed in the prefrontal cortex during the added-purpose task than during the single-purpose task. These results were noted with both right and left hands. [Conclusion] According to our findings, added-purpose activity can bring about more activation in the prefrontal cortex, which may provide occupational therapists with effective guides in therapeutic practice.