Diersch Nadine, Jones Alex L, Cross Emily S
Wales Institute of Cognitive Neuroscience, School of Psychology, Bangor University, Gwynedd, United Kingdom.
Aging and Cognition Research Group, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.
Hum Brain Mapp. 2016 Jan;37(1):54-66. doi: 10.1002/hbm.23012. Epub 2015 Oct 27.
Successful social interactions depend on the ability to anticipate other people's actions. Current conceptualizations of brain function propose that causes of sensory input are inferred through their integration with internal predictions generated in the observer's motor system during action observation. Less is known concerning how action prediction changes with age. Previously we showed that internal action representations are less specific in older compared with younger adults at behavioral and neural levels. Here, we characterize how neural activity varies while healthy older adults aged 56-71 years predict the time-course of an unfolding action as well as the relation to task performance. By using fMRI, brain activity was measured while participants observed partly occluded actions and judged the temporal coherence of the action continuation that was manipulated. We found that neural activity in frontoparietal and occipitotemporal regions increased the more an action continuation was shifted backwards in time. Action continuations that were shifted towards the future preferentially engaged early visual cortices. Increasing age was associated with neural activity that extended from posterior to anterior regions in frontal and superior temporal cortices. Lower sensitivity in action prediction resulted in activity increases in the caudate. These results imply that the neural implementation of predicting actions undergoes similar changes as the neural process of executing actions in older adults. The comparison between internal predictions and sensory input seems to become less precise with age leading to difficulties in anticipating observed actions accurately, possibly due to less specific internal action models.
成功的社交互动取决于预测他人行为的能力。当前对大脑功能的概念化认为，通过在动作观察期间将感觉输入与观察者运动系统中生成的内部预测进行整合，可以推断出感觉输入的原因。关于动作预测如何随年龄变化，人们了解得较少。此前我们发现，与年轻人相比，老年人在行为和神经层面的内部动作表征不那么具体。在此，我们描述了56至71岁健康老年人在预测一个正在展开的动作的时间进程时神经活动如何变化，以及与任务表现的关系。通过功能磁共振成像（fMRI），在参与者观察部分遮挡的动作并判断被操纵的动作延续的时间连贯性时测量大脑活动。我们发现，动作延续在时间上向后偏移得越多，额顶叶和枕颞叶区域的神经活动增加得越多。向未来偏移的动作延续优先激活早期视觉皮层。年龄增长与额叶和颞上叶皮层从后部到前部区域的神经活动扩展有关。动作预测的较低敏感性导致尾状核活动增加。这些结果表明，在老年人中，预测动作的神经机制与执行动作的神经过程经历了类似的变化。随着年龄增长，内部预测与感觉输入之间的比较似乎变得不那么精确，导致难以准确预测观察到的动作，这可能是由于内部动作模型不那么具体所致。
