T-test for middle level measures.

Addiction is a multifactorial biological and behavioral disorder that is studied using animal models, based on simple behavioral responses in isolated individuals. A couple of decades ago it was shown that Drosophila melanogaster can serve as a model organism for behaviors related to alcohol, nicotine and cocaine (COC) addiction. Scoring of COC-induced behaviors in a large group of flies has been technologically challenging, so we have applied a local, middle and global level of network-based analyses to study social interaction networks (SINs) among a group of 30 untreated males compared to those that have been orally administered with 0.50 mg/mL of COC for 24 hours. In this study, we have confirmed the previously described increase in locomotion upon COC feeding. We have isolated new network-based measures associated with COC, and influenced by group on the individual behavior. COC fed flies showed a longer duration of interactions on the local level, and formed larger, more densely populated and compact, communities at the middle level. Untreated flies have a higher number of interactions with other flies in a group at the local level, and at the middle level, these interactions led to the formation of separated communities. Although the network density at the global level is higher in COC fed flies, at the middle level the modularity is higher in untreated flies. One COC specific behavior that we have isolated was an increase in the proportion of individuals that do not interact with the rest of the group, considered as the individual difference in COC induced behavior and/or consequence of group influence on individual behavior. Our approach can be expanded on different classes of drugs with the same acute response as COC to determine drug specific network-based measures and could serve as a tool to determinate genetic and environmental factors that influence both drug addiction and social interaction.

成瘾是一种多因素的生物与行为障碍，过往相关研究多依托动物模型，基于孤立个体的简单行为反应开展。数十年前已有研究证实，黑腹果蝇（Drosophila melanogaster）可作为酒精、尼古丁与可卡因（COC）成瘾相关行为的模式生物。对大量果蝇的可卡因诱导行为进行评分曾面临技术挑战，因此本研究针对30只未处理雄性果蝇与经口给予0.50 mg/mL可卡因（COC）处理24小时的果蝇群体，分别从局部、中间及全局三个网络层级开展基于网络的社交互动网络（SINs）分析。本研究证实了此前报道的可卡因摄食后运动活性增强现象，同时分离出了与可卡因相关的新型网络分析指标，且此类指标会受到群体因素对个体行为的影响。经可卡因处理的果蝇在局部层级的互动时长更长，并在中间层级形成了规模更大、密度更高且结构更紧凑的社群。未处理果蝇在局部层级的群体互动次数更多；在中间层级，此类互动会形成相互分离的社群。尽管全局层级的网络密度在可卡因处理组果蝇中更高，但未处理组在中间层级的模块化程度更高。我们分离出的一项可卡因特异性行为表现为：不与群体其他个体互动的个体比例升高，这可视为可卡因诱导行为的个体差异，以及/或群体因素对个体行为产生影响的结果。本研究方法可推广至与可卡因具有相同急性反应的其他各类药物，以确定药物特异性的网络分析指标，同时可作为一种工具，用于探究影响药物成瘾与社交互动的遗传与环境因素。