Previous studies have shown that imagined walking ability decreases with age in a similar manner as actual walking ability; however, little is known about the neural mechanisms underlying this aging effect. The present study investigates this issue, focusing on the effect of task difficulty and the involvement of the prefrontal cortex (PFC). Twenty healthy right-handed older adults (mean age 74.5 ± 3.3 years) participated in two experiments. In Experiment 1, the time participants took for actual and imagined walking along a 5-m walkway of three different path widths (15, 25, and 50 cm) were compared. In Experiment 2, the participants imagined walking along the aforementioned paths while PFC activity was measured using functional near-infrared spectroscopy. At the behavioral level, older adults exhibited longer mental and actual walking times for narrower paths and tended to overestimate their imagined walking times over their actual ones. However, overall, the magnitude of the overestimation did not differ by task difficulty. Regarding brain activity, older adults who overestimated mental walking times to a greater degree in the narrowest path exhibited decreased activation in the bilateral PFC. Moreover, compared with young adults in our previous study (Kotegawa et al., 2020), older adults with higher gait ability exhibited the same or smaller mental/actual walking times as well as decreased bilateral PFC activation in the most difficult condition. These results suggest that older adults, especially those with higher gait ability, can utilize neural mechanisms that are different from those of young adults when generating gait motor imagery.

先前的研究表明，想象的步行能力随着年龄的增长而下降，其方式与实际步行能力相似；然而，人们对这种衰老效应背后的神经机制知之甚少。本研究调查了这个问题，重点是任务难度的影响和前额叶皮层 (PFC) 的参与。20 名健康的右利手老年人（平均年龄 74.5 ± 3.3 岁）参加了两个实验。在实验 1 中，比较了参与者沿着三种不同路径宽度（15、25 和 50 厘米）的 5 米人行道实际行走和想象行走所花费的时间。在实验 2 中，参与者想象沿着上述路径行走，同时使用功能性近红外光谱测量 PFC 活性。在行为层面，老年人在较窄的路径上表现出更长的心理和实际步行时间，并且倾向于高估他们想象的步行时间而不是实际步行时间。然而，总体而言，高估的程度并没有因任务难度而异。关于大脑活动，在最狭窄的路径上更大程度地高估精神行走时间的老年人表现出双侧 PFC 的激活减少。此外，与我们之前的研究（Kotegawa 等人，2020 年）中的年轻人相比，步态能力较高的老年人在最困难的情况下表现出相同或更短的心理/实际步行时间以及双侧 PFC 激活减少。这些结果表明，老年人，尤其是那些步态能力较高的人，