Abstract
The purpose of this study was to investigate neuronal mechanisms active during the percep-tion of forward postural limits in a standing po-sition and to specify fall-related brain activity using optical functional near-infrared spectros-copy. The study group included six right-handed, healthy female volunteers (range: 19, 20 years). The optical imaging device comprised 16 opto-des designed to provide 24-channel recording of changes in hemoglobin oxygenation. We meas-ured the changes of oxygenated hemoglobin levels in the frontal region when subjects per-ceived reachability in a standing position. Com- pared with those in other regions, the oxygen-ated hemoglobin levels in the right frontal region compatible with the right prefrontal cortex sig-nificantly increased. This result suggests that brain activities in the right prefrontal cortex are related to perception of reachability. Overesti-mation of postural limits has been reported as one of the risk factor for falling. This overesti-mation 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 pre-venting accidental falls in the elderly and in pa-tients with neurological disorders.
Highlights
Most people can appropriately perceive reachability, which is defined as the distance to which one could reach if executing the reach
All meanZ scores of oxygenated hemoglobin (oxy-Hb), deoxy-Hb and total-Hb in each channel ranged from -1 to 2 and we judged that hemoglobin levels were not changed by the control task
The effect tended to increase in the right frontal region during the perception of reachability
Summary
Most people can appropriately perceive reachability, which is defined as the distance to which one could reach if executing the reach. Our previous study and others have reported that elderly and neurological patients, including patients with Parkinson’s disease, tended to overestimate their reachability when standing, and overestimate their own postural limits, even if a target is not within actual reach [3,5] This overestimation has been reported as one of the risk factors of multiple falls [6]. Functional near-infrared spectroscopy (fNIRS) can evaluate cortical activity by measuring the changes of hemoglobin oxygenation of blood within a few centimeters of the skull surface [7] We adapted this technique to our study since it was suitable for use during dynamic tasks such as walking and in a standing position [8,9]. The purpose of this study was to clarify neuronal mechanism during the perception of forward postural limits in a standing position by fNIRS and to specify fall-related brain regions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
