Department of Psychology and Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
J Neurophysiol. 2021 Jul 1;126(1):313-329. doi: 10.1152/jn.00003.2021. Epub 2021 Jun 16.
When performing a physically demanding behavior, sometimes the optimal choice is to quit the behavior rather than persist to minimize energy expenditure for the benefits gained. The dorsomedial prefrontal cortex (dmPFC), consisting of the anterior cingulate cortex and secondary motor area, likely contributes toward such utility assessments. Here, we examined how male rat dmPFC single unit and ensemble-level activity corresponded to changes in task utility and quitting in an effortful weight lifting task. Rats carried out two task paradigms: one that became progressively more physically demanding over time and a second fixed effort version. Rats could quit the task at any time. Dorsomedial PFC neurons were highly responsive to each behavioral stage of the task, consisting of rope pulling, reward retrieval, and reward area leaving. Activity was highest early in sessions, commensurate with the highest relative task utility, then decreased until the point of quitting. Neural ensembles consistently represented the sequential behavioral phases of the task. However, these representations were modified over time and became more distinct over the course of the session. These results suggest that dmPFC neurons represent behavioral states that are dynamically modified as behaviors lose their utility, culminating in task quitting. When carrying out a physically demanding task, animals must continually assess whether to persist or quit. In this study, we recorded neurons in the dorsomedial prefrontal cortex (dmPFC) of rats as they carried out a challenging weightlifting task, up to the point of quitting. We demonstrate that dmPFC neurons form a representation of the task that is modified, via a decrease in firing rate, by the decreasing the utility of the task that may signal quitting.
当进行体力要求高的行为时，有时最优的选择是放弃行为，而不是坚持下去，以最小化获得收益所需的能量消耗。背内侧前额叶皮层（dmPFC），由前扣带皮层和次级运动区组成，可能有助于这种效用评估。在这里，我们研究了雄性大鼠 dmPFC 单个神经元和整体活动如何对应于费力举重任务中的任务效用变化和放弃。大鼠进行了两种任务范式：一种随着时间的推移变得越来越体力要求高，另一种是固定努力版本。大鼠可以随时放弃任务。背内侧前额叶皮层神经元对任务的每个行为阶段高度敏感，包括绳索拉动、奖励检索和奖励区域离开。活动在会议早期最高，与最高相对任务效用相称，然后减少，直到放弃的地步。神经集合始终代表任务的顺序行为阶段。然而，这些表示随着时间的推移而被修改，并且在会议过程中变得更加明显。这些结果表明，dmPFC 神经元代表行为状态，这些状态随着行为失去效用而动态修改，最终导致任务放弃。当执行体力要求高的任务时，动物必须不断评估是坚持还是放弃。在这项研究中，我们记录了大鼠背内侧前额叶皮层（dmPFC）中的神经元，当它们执行一项具有挑战性的举重任务时，直到放弃的地步。我们证明，dmPFC 神经元形成了对任务的表示，通过降低发射率来修改，通过降低任务的效用来修改，这可能表示放弃。
