A Biological Framework of Reduced Physical and Social Activity across the Lifespan

几十年来，我们已经知道，身体和社交活动可以带来重大的健康益处，包括预防晚年的不健康状况和改善生病时的症状。尽管有这些好处，但许多人不经常锻炼，也不参与社交活动。随着人们年龄的增长，这种缺乏活动的情况也会增加，给世界各地的卫生系统带来巨大成本，并给个人带来重大成本。为什么人们不运动呢？阻碍积极生活的一个关键因素是动机。更有动力的人更积极。即使在其他方面健康的人也会遭受高度的动机问题，如社交冷漠（人们喜欢社交互动，但只是没有意愿参与其中）或疲劳（人们在少量的努力后感到筋疲力尽）。此外，这些动机障碍随着人们年龄的增长而增加。然而，我们对人们动机不同的原因了解甚少。是否存在社会冷漠和疲劳的生理现象？这项拟议研究的首要目标是确定大脑中某些系统的工作方式差异与人们在社交上的冷漠或疲劳程度的差异之间的关系，并研究随着年龄的增长，大脑的变化是如何导致动机降低的。为了做到这一点，我将扩展基础神经科学的最新进展，这些进展为大脑如何激发行为提供了丰富的理解。在这项研究中，有人认为动机降低可能是由于对努力行为的高度敏感。更有动力的人会发现同样的事情不那么费力。在这里，我建议研究在健康人群中，随着年龄的增长，努力敏感度的不同方面是如何与疲劳和社会冷漠联系起来的。为此，我将对健康的人类志愿者进行研究，使用多种技术，包括脑成像、脑刺激和手机游戏，并使用精确的计算方法对努力敏感性进行量化。将所有这些方法结合起来，我将能够回答有关大脑系统的具体问题，这些系统在社交场合和疲惫时激发行为。通过比较年轻人和老年人对努力敏感度的大脑系统，我将试图了解随着年龄的增长，大脑中的哪些变化可能导致更高程度的社会冷漠和疲劳。总之，拟议的研究将检验的关键问题是：1)社会冷漠和疲劳是否可以表征为健康人群对不同方面努力的敏感度增加？2)在整个生命周期中，社会冷漠和疲劳是否会因为努力敏感度的提高而增加？3)大脑中的哪些系统是努力敏感度不同方面的基础，它们与社会冷漠和疲劳有关吗？4)老年人这些大脑系统的变化是否与努力敏感度、社交冷漠和疲劳增加有关？5)在一个独特的个体样本中，将深部脑刺激器植入特定的大脑区域，是否能提供这些区域与努力敏感性有因果关系的证据？这项工作将在牛津大学实验心理学系进行。首席研究员（Apps博士）将与一名博士后研究员、纳菲尔德外科科学部的外科顾问、威康综合神经科学信托中心和一家移动大脑训练公司合作。

For decades, we have known that being physically and socially active can have major health benefits, including the prevention of later life ill-health and the improvement of symptoms when sick. Despite these benefits, many people do not engage in regular exercise and are socially dis-engaged. Such inactivity increases as people get older, leading to significant costs to health systems across the world, as well as major personal costs to the individual.Why aren't people more active? A crucial factor that prevents an active life is motivation. People who are more motivated are more active. Even otherwise healthy people can suffer from high levels of motivation problems such as social apathy (people enjoy social interactions but simply don't have the will to engage in them) or fatigue (people who feeling exhausted after small levels of exertion). Moreover these motivational impairments increase as people get older. Yet, we understand very little about why people vary in motivation. Is there a biology of social apathy and fatigue? The overarching aim of the proposed research is to identify how differences in how certain systems in the brain work, relates to differences in how socially apathetic or fatigued people are, and to examine how changes in the brain lead to reduced motivation as we get older. To do this I will extend recent advancements in basic neuroscience that has provided a rich understanding of how the brain motivates behaviour. Within this research it has been suggested that reduced motivation might be due to a heightened sensitivity to how effortful actions are. People who are more motivated find the same actions less effortful. Here, I propose to examine how different aspects of effort sensitivity may be linked to fatigue and social apathy in healthy people as they get older. To do this, I will perform studies in healthy human volunteers using a number of techniques including brain imaging, brain stimulation and a mobile phone game, with effort sensitivity quantified using precise computational approaches. Using all of these approaches together I will be able to answer specific questions about the systems in the brain that motivate behaviour in social situations and when getting exhausted. By comparing the brain systems underlying effort sensitivity in young and older people, I will try and understand what changes in the brain may lead to higher levels of social apathy and fatigue as people get older. In summary, the key questions that the proposed research would examine are:1) Can social apathy and fatigue be characterised as increased sensitivity to different aspects of effort in healthy people? 2) Do social apathy and fatigue increase across the lifespan because of heightened effort sensitivity? 3) What systems in the brain underlie different aspects of effort sensitivity and are they linked to social apathy and fatigue? 4) Are changes in these brain systems in older adults linked to increased effort sensitivity, social apathy and fatigue? 5) Can stimulating these brain areas in a unique sample of individuals with deep brain stimulators implanted into specific brain areas provide evidence of these regions being causally involved in effort sensitivity? This work will be carried out in the Department of Experimental Psychology, at the University of Oxford. The principal investigator (Dr. Apps) will work in collaboration with a postdoctoral researcher, consultant surgeons in the Nuffield Department of Surgical Science, the Wellcome trust Centre for integrated neuroscience and a mobile brain training company.