Hashimoto Kohei, Terao Kanta, Mizunami Makoto
Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan.
Academic Assembly Institute of Science and Engineering, Shimane University, Matsue 690-8504, Japan.
Neurobiol Learn Mem. 2025 Jan;217:108019. doi: 10.1016/j.nlm.2024.108019. Epub 2024 Dec 24.
Social learning, learning from other individuals, has been demonstrated in many animals, including insects, but its detailed neural mechanisms remain virtually unknown. We showed that crickets (Gryllus bimaculatus) exhibit aversive social learning with a dead conspecific. When a learner cricket was trained to observe a dead cricket on a drinking apparatus, the learner avoided the odor of that apparatus thereafter. Here we investigated the hypothesis that this social learning is achieved by first-order Pavlovian conditioning of an odor (conditioned stimulus) and a dead conspecific (unconditioned stimulus, US). Injection of a dopamine receptor antagonist (flupentixol) before training or testing impaired the learning or execution of the response to the learned odor, as we reported in aversive non-social Pavlovian conditioning in crickets. Moreover, crickets that were trained with a dead conspecific and then received revaluation of the dead conspecific by pairing it with water reward exhibited an appetitive conditioned response (CR) to the odor paired with the dead conspecific. This suggests that execution of the CR is governed by the current value of the US as in non-social Pavlovian conditioning. In addition, we previously suggested that appetitive social learning with a living conspecific is based on second-order conditioning (SOC), and here we showed that SOC is achieved when crickets experienced pairing of a dead conspecific with water reward before experiencing social learning training with a dead conspecific. We conclude that social learning with a dead conspecific is based on Pavlovian conditioning and that this learning can be extended to second-order social learning.
社会学习，即从其他个体身上学习，已在包括昆虫在内的许多动物中得到证实，但其详细的神经机制几乎仍不为人所知。我们发现，双斑蟋会对死去的同种个体表现出厌恶型社会学习。当一只学习的蟋蟀被训练观察饮水装置上的一只死蟋蟀后，这只学习的蟋蟀此后会避开该装置的气味。在此，我们研究了这样一种假设，即这种社会学习是通过对一种气味（条件刺激）和一只死去的同种个体（非条件刺激，US）进行一阶巴甫洛夫条件反射来实现的。如我们在蟋蟀的厌恶型非社会巴甫洛夫条件反射研究中所报告的那样，在训练或测试前注射多巴胺受体拮抗剂（氟哌噻吨）会损害对所学气味的学习或反应的执行。此外，用死去的同种个体进行训练，然后通过将其与水奖励配对来对死去的同种个体进行重新评估的蟋蟀，会对与死去的同种个体配对的气味表现出一种偏好型条件反应（CR）。这表明，与非社会巴甫洛夫条件反射一样，CR的执行受US当前值的支配。此外，我们之前曾提出，与活着的同种个体进行的偏好型社会学习基于二阶条件反射（SOC），并且在此我们表明，当蟋蟀在经历与死去的同种个体的社会学习训练之前，先经历了死去的同种个体与水奖励的配对时，SOC就会实现。我们得出结论，与死去的同种个体进行的社会学习基于巴甫洛夫条件反射，并且这种学习可以扩展到二阶社会学习。
