Functional MR imaging of a simulated balance task

• Functional MRI data were collected from supine subjects during a simulated balance task.
• Subjects controlled cursor position on a screen by generating ankle torques against an MRI-compatible force platform.
• Subjects also performed an additional ankle torque task that did not involve a balance simulation.
• Balance simulation elicited activity in brain regions consistent with studies of active and imagined balance.
• Results demonstrate utility of using a force platform to simulate active balance control during MR imaging.

Human postural control, which relies on information from vestibular, visual, and proprioceptive inputs, degrades with aging, and falls are the leading cause of injury in older adults. In the last decade, functional neuroimaging studies have been performed in order to gain a greater understanding of the supraspinal control of balance and walking. It is known that active balancing involves cortical and subcortical structures in the brain, but neuroimaging of the brain during these tasks has been limited. The study of the effect of aging on the functional neuroimaging of posture and gait has only recently been undertaken. In this study, an MRI-compatible force platform was developed to simulate active balance control. Eleven healthy participants (mean age 75±5 yr) performed an active balance simulation task by using visual feedback to control anterior–posterior center of pressure movements generated by ankle dorsiflexor (DF) and plantarflexor (PF) movements, in a pattern consistent with upright stance control. An additional ankle DF/PF exertion task was performed. During both the active balance simulation and the ankle DF/PF tasks, the bilateral fusiform gyrus and middle temporal gyrus, right inferior, middle, and superior frontal gyrii were activated. No areas were found to be more active during the ankle DF/PF task when compared with the active balance simulation task. When compared to the ankle DF/PF task, the active balance simulation task elicited greater activation in the middle and superior temporal gyrii, insula, and a large cluster that covered the corpus callosum, superior and medial frontal gyrii, as well as the anterior cingulate and caudate nucleus. This study demonstrates the utility in using a force platform to simulate active balance control during MR imaging that elicits activity in cortical regions consistent with studies of active balance and mental imagery of balance.