Cerebral oxygenation patterns during walking with wearable hip-assist robot in elderly adults: A fNIRS study

Abstract

The purpose of this study was to investigate the modulating effect of wearable hip-assist robot, Gait Enhancing Mechatronic System (GEMS, Samsung Electronics Co., Ltd., Korea), on cerebral oxygenation patterns during treadmill gait in elderly adults. Twenty elderly adults participated in this study. Each subject performed treadmill walking task at self-selected speed either with assistance of GEMS (GEMS) or without assistance of GEMS (NoGEMS). An experimental session began with a fixed standing condition (60 s), followed by one of the 2 walking conditions (60 s) and then a resting condition (60 s) for five repetitions. For analyzing the cortical activation, a task period was divided into the early and late phase. Cerebral oxygenation was measured by oxyhemoglobin (OxyHb) concentration using the functional near infrared spectroscopy (fNIRS) imaging system (NIRScout, NIRx Medical Technology, LLC, Germany) covering bilateral prefrontal cortices (PFC), premotor cortices (PMC), supplemental motor areas (SMA), and lower limb sensorimotor cortices (SMC). We observed less OxyHb concentration over the lower limb SMC, SMA and PMC regions in the late phase of gait with GEMS than NoGEMS conditions. In addition, PFC activity demonstrated left side predominance in GEMS condition. Additional brain activity in older compared to younger adults may be a reflection of compensatory mechanism to improve performance in a specific task which is associated with less efficient use of neural resources. Walking with GEMS demonstrated decreased activity of specific brain regions related with gait and might represent increased efficiency of neural resources. In addition, increased hemispheric asymmetry during walking with GEMS might reflect less need for compensation through right prefrontal activity.