Right prefrontal cortex is activated for perceiving postural limits: a functional near-infrared spectroscopy study

Abstract

The purpose of this study was to investigate neuronal mechanisms active during the perception of forward postural limits in a standing position and to specify fall-related brain activity using optical functional near-infrared spectroscopy. The study group included six right-handed, healthy female volunteers (range: 19, 20 years). The optical imaging device comprised 16 optodes designed to provide 24-channel recording of changes in hemoglobin oxygenation. We measured the changes of oxygenated hemoglobin levels in the frontal region when subjects perceived reachability in a standing position. Compared with those in other regions, the oxygenated hemoglobin levels in the right frontal region compatible with the right prefrontal cortex significantly increased. This result suggests that brain activities in the right prefrontal cortex are related to perception of reachability. Overestimation of postural limits has been reported as one of the risk factor for falling. This overestimation might be induced by dysfunction in the prefrontal cortex, resulting in a failure to inhibit a motor program that would have caused a loss of balance in reaching. Activation of the right prefrontal cortex may be a key factor for preventing accidental falls in the elderly and in patients with neurological disorders.