The present study using near-infrared spectroscopy (NIRS) examined prefrontal activation associated with maze-solving performance and preplanning in adult humans. The participants were required to solve an eight-arm shuriken-shaped maze, comparable to the one used for pigeons to behaviorally assess preplanning, by moving a target square to a goal square presented on a touch-sensitive screen. The maze-solution phase was preceded by a 10-s preview phase during which the participants could observe but were not allowed to solve the maze. The participants, in contrast with pigeons, made few incorrect responses in trials in which the goal jumped to the end of another arm following the preview phase. The NIRS data revealed two-peak waveforms, with the first peak during the preview phase and the second one during the solution phase, most evidently in baseline trials. Significant increase in oxy-Hb was found near right dorsolateral prefrontal cortex (DLPFC) during the solution phase, while hemodynamic changes during the preview phase failed to reach statistical significance. The data suggest that, although human adults may have planned the solution of the maze during the preview phase, they needed to employ relatively small amount of cognitive resources throughout this task. Developmental and comparative perspectives for investigating neural correlates of preplanning are discussed.

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