Maksimoski Alyse N, Levenson Taviah A, Zhao Changjiu, Riters Lauren V
Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
PLoS One. 2025 Jan 28;20(1):e0318340. doi: 10.1371/journal.pone.0318340. eCollection 2025.
It has been proposed that social groups are maintained both by reward resulting from positive social interactions and by the reduction of a negative state that would otherwise be caused by social separation. European starlings, Sturnus vulgaris, develop strong conditioned place preferences for places associated with the production of song in flocks outside the breeding season (gregarious song) and singers are motivated to rejoin the flock following removal. This indicates that the act of singing in flocks is associated with a positive affective state and raises the possibility that reward induced by song in flocks may play a role in flock maintenance. The goal of this study was to begin to test this hypothesis. We found that birds that sang full songs developed stronger conditioned place preferences than non-singing birds for places associated with flock mates, indicating that singers find the presence of flock mates to be rewarding. Regardless of song rate, the presence of flock mates also induced analgesia (a reflection of the reduction of a negative state). This form of analgesia has been shown to be an indirect measure of opioid release, suggesting that the presence of flock mates may induce opioid-mediated reward. Consistent with this possibility, the numbers of mu opioid receptor immunolabeled cells in the nucleus accumbens correlated positively with measurements of gregarious song and other social behaviors. Results suggest that both gregarious song and social contact promote flock cohesion and that opioids released onto mu opioid receptors in the nucleus accumbens may play an important role.
有人提出，社会群体是通过积极社会互动产生的奖励以及减少因社会隔离否则会导致的消极状态来维持的。欧洲椋鸟（Sturnus vulgaris）在繁殖季节之外对与群体中鸣叫产生相关的地方（群居鸣叫）形成强烈的条件性位置偏好，并且在被移除后，鸣叫者有动机重新加入群体。这表明在群体中鸣叫的行为与积极的情感状态相关联，并增加了群体中鸣叫诱导的奖励可能在群体维持中起作用的可能性。本研究的目的是开始检验这一假设。我们发现，与不鸣叫的鸟类相比，完整鸣叫的鸟类对与群体同伴相关的地方形成了更强的条件性位置偏好，这表明鸣叫者发现群体同伴的存在是有奖励的。无论鸣叫频率如何，群体同伴的存在也会诱导镇痛（消极状态减轻的一种反映）。这种形式的镇痛已被证明是阿片类物质释放的一种间接测量方法，表明群体同伴的存在可能诱导阿片类物质介导的奖励。与这种可能性一致，伏隔核中μ阿片受体免疫标记细胞的数量与群居鸣叫和其他社会行为的测量结果呈正相关。结果表明，群居鸣叫和社会接触都促进了群体凝聚力，并且释放到伏隔核中μ阿片受体上的阿片类物质可能起重要作用。
