Department of Psychology, University of Otago, Dunedin 9016, New Zealand.
Department of Psychology, University of Otago, Dunedin 9016, New Zealand; Brain Health Research Centre, Division of Sciences, University of Otago, Dunedin 9016, New Zealand.
Brain Res. 2020 Oct 15;1745:146920. doi: 10.1016/j.brainres.2020.146920. Epub 2020 May 30.
Many previous studies have shown that hippocampal place cells respond to the spatial position of the animal itself. Several recent studies have shown that place cells in an observer animal can also encode the location of a conspecific. The interpretation of these previous studies is, however, compromised by the fact that the observer animal was required to complete a movement that was either a duplication of the others trajectory, or a modification of it. This raises the possibility that the observed representation of the other, may have instead been a plan for the self. To test for a representation of a conspecific in a task where immediate behaviour was not immediately required of the observer, Sprague-Dawley rats were trained to run the length of a shuttle box for a food reward. They then observed a second animal (the runner) performing the same task. Positional data was obtained from the runner, while hippocampal single unit data was collected from the observer. Hippocampal single units were observed to have only limited, low resolution, firing rate-modulated representations of the runner animal. There was also evidence of a weak relationship between place cell spatial firing representations of the self and other. Some above-chance evidence of phase-coding of the runner's position was also observed in the observer animals, with an observer-centred reference frame. These results indicate that hippocampal place cells encode some limited spatial information about others when the observer's subsequent behaviour is not dependent on that of the observed.
许多先前的研究表明，海马体位置细胞对动物自身的空间位置作出反应。最近的几项研究表明，观察动物的位置细胞也可以对同种动物的位置进行编码。然而，这些先前研究的解释受到以下事实的影响，即观察动物需要完成一个与其他动物的轨迹要么重复，要么是对其进行修改的运动。这就提出了一个可能性，即观察到的另一个代表，可能是对自身的一个计划。为了测试在观察动物没有被立即要求采取直接行为的任务中是否存在同种动物的表示，Sprague-Dawley 大鼠被训练在穿梭箱中奔跑以获得食物奖励。然后，它们观察第二只动物（跑步者）执行相同的任务。从跑步者那里获取位置数据，同时从观察者那里收集海马体单个单元数据。观察到海马体单个单元仅对跑步者动物具有有限的、低分辨率的、发射率调制的表示。还存在自我和其他的位置细胞空间发射表示之间存在弱关系的证据。在以观察者为中心的参考框架中，还观察到跑步者位置的相位编码存在一些微弱的、高于偶然的证据。这些结果表明，当观察者的后续行为不依赖于观察到的行为时，海马体位置细胞会对其他动物的某些有限的空间信息进行编码。
