Huntington's Disease Centre, UCL Queen Square Institute of Neurology, University College London, Russell Square House, 10-12 Russell Square, London, WC1B 5EH, UK.
Max Planck UCL Centre for Computational Psychiatry and Ageing Research, UCL Queen Square Institute of Neurology, University College London, Russell Square House, 10-12 Russell Square, London, WC1B 5EH, UK.
Psychol Med. 2023 Apr;53(5):1850-1859. doi: 10.1017/S0033291721003469. Epub 2021 Oct 12.
Apathy, a disabling and poorly understood neuropsychiatric symptom, is characterised by impaired self-initiated behaviour. It has been hypothesised that the (OCT) may be a key computational variable linking self-initiated behaviour with motivational status. OCT represents the amount of reward which is foregone per second if no action is taken. Using a novel behavioural task and computational modelling, we investigated the relationship between OCT, self-initiation and apathy. We predicted that higher OCT would engender shorter action latencies, and that individuals with greater sensitivity to OCT would have higher behavioural apathy.
We modulated the OCT in a novel task called the 'Fisherman Game', Participants freely chose when to self-initiate actions to either collect rewards, or on occasion, to complete non-rewarding actions. We measured the relationship between action latencies, OCT and apathy for each participant across two independent non-clinical studies, one under laboratory conditions ( = 21) and one online ( = 90). 'Average-reward' reinforcement learning was used to model our data. We replicated our findings across both studies.
We show that the latency of self-initiation is driven by changes in the OCT. Furthermore, we demonstrate, for the first time, that participants with higher apathy showed greater sensitivity to changes in OCT in younger adults. Our model shows that apathetic individuals experienced greatest change in subjective OCT during our task as a consequence of being more sensitive to rewards.
Our results suggest that OCT is an important variable for determining free-operant action initiation and understanding apathy.
冷漠是一种使人丧失能力且尚未被充分了解的神经精神症状，其特征是自我发起行为受损。有人假设，（OCT）可能是将自我发起的行为与动机状态联系起来的关键计算变量。OCT 代表如果不采取行动，每秒会错过多少奖励。使用一种新颖的行为任务和计算模型，我们研究了 OCT、自我启动和冷漠之间的关系。我们预测，较高的 OCT 将产生较短的动作潜伏期，并且对 OCT 更敏感的个体将具有更高的行为冷漠。
我们在一种名为“渔夫游戏”的新任务中调节了 OCT，参与者可以自由选择何时自我启动动作以收集奖励，或者有时完成非奖励动作。我们测量了每个参与者在两个独立的非临床研究中的动作潜伏期、OCT 和冷漠之间的关系，一个在实验室条件下（n=21），一个在线（n=90）。“平均奖励”强化学习用于对我们的数据进行建模。我们在两项研究中都复制了我们的发现。
我们表明，自我启动的潜伏期是由 OCT 的变化驱动的。此外，我们首次证明，在年轻成年人中，冷漠程度较高的参与者对 OCT 变化的敏感性更高。我们的模型表明，冷漠个体在我们的任务中经历了最大的主观 OCT 变化，因为他们对奖励更敏感。
我们的结果表明，OCT 是决定自由操作动作启动和理解冷漠的重要变量。
