Ward Nick S, Swayne Orlando B C, Newton Jennifer M
Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK.
Neurobiol Aging. 2008 Sep;29(9):1434-46. doi: 10.1016/j.neurobiolaging.2007.04.017. Epub 2007 Jun 12.
Functional imaging studies in humans have demonstrated widespread age-related changes in cortical motor networks. However, the relative contribution of cortical regions during motor performance varies not only with age but with task parameters. In this study, we investigated whether motor system activity during a task involving increasingly forceful hand grips was influenced by age. Forty right-handed volunteers underwent functional magnetic brain imaging whilst performing repetitive isometric hand grips with either hand in separate sessions. We found no age-related changes in the average size and shape of the task-related blood oxygen level dependent (BOLD) signal in contralateral primary motor cortex (M1), but did observe reduced ipsilateral M1 deactivation in older subjects (both hands). Furthermore, task-related activity co-varied positively with force output in a number of brain regions, but was less prominent with advancing age in contralateral M1, cingulate sulcus (both hands), sensory and premotor cortices (right hand). These results indicate that a reduced ability to modulate activity in appropriate motor networks when required may contribute to age-related decline in motor performance.
针对人类的功能成像研究已证明，皮质运动网络中存在广泛的与年龄相关的变化。然而，在运动表现过程中，皮质区域的相对贡献不仅随年龄变化，还随任务参数而变化。在本研究中，我们调查了在一项涉及逐渐加大握力的任务中，运动系统活动是否受年龄影响。40名右利手志愿者在分别的实验环节中，用任意一只手进行重复性等长握力动作时接受了功能性脑磁图成像检查。我们发现，在对侧初级运动皮层（M1）中，与任务相关的血氧水平依赖（BOLD）信号的平均大小和形状不存在与年龄相关的变化，但确实观察到老年受试者（两只手）同侧M1的失活减少。此外，在多个脑区，与任务相关的活动与力量输出呈正相关，但在对侧M1、扣带沟（两只手）、感觉和运动前皮层（右手）中，随着年龄增长这种相关性不那么明显。这些结果表明，在需要时调节适当运动网络活动的能力下降，可能是导致与年龄相关的运动表现下降的原因。
