Mulvihill Kevin G, Brudzynski Stefan M
Department of Psychology, Brock University, St. Catharines, ON L2S 3A1, Canada.
Department of Psychology, Brock University, St. Catharines, ON L2S 3A1, Canada.
Physiol Behav. 2018 Nov 1;196:200-207. doi: 10.1016/j.physbeh.2018.09.005. Epub 2018 Sep 7.
The emission of 50 kHz ultrasonic vocalizations (USVs) by rats is thought to represent a measurable expression of the individuals underlying emotional state. These calls are also posited as fulfilling important communicative functions among conspecifics. In addition to social situations, 50 kHz USVs are recorded in a variety of reward-related contexts including sugary foods and drink, consumable ethanol, and drugs of abuse. The current study sought to directly compare several of these behavioural contexts in their capability to induce and modulate 50 kHz USV emission in adult male rats. Using two social conditions (exposure of naïve rat to a naturally cycling female and reuniting with a same-sex cage partner) and two non-social conditions (access to consumables as Fruit Loops or 2% ethanol v/v), we analyzed USVs recorded in 6 stimulus-presentation sessions. Only the female-exposure condition was found to increase 50 kHz call rate significantly over baseline, and this induction sensitized across 4 standard recording sessions. The use of a same-sex cage-mate and the two consumable food rewards did not elicit higher than baseline 50 kHz calling. None of the behavioural contexts altered the acoustic parameters (peak frequency, duration, and bandwidth) of emitted 50 kHz calls. In counter-balanced recording sessions, calling across all groups was significantly reduced by pre-treatment with the dopamine antagonist haloperidol compared with vehicle. Non-social conditions appeared to induce a greater proportion of flat calls at the expense of non-trill FM calls, while the reverse was seen for social conditions. However, the type of food reward and the type of social context mattered for proportion of flat and trill calls respectively. When compared with a control, access to sugary food but not ethanol induced a greater proportion of flat calls, and the female but not the cage-mate stimulus induced a greater proportion of trill calls.
大鼠发出50千赫兹的超声波发声（USV）被认为是其潜在情绪状态的一种可测量的表现形式。这些叫声也被认为在同种个体之间发挥着重要的交流功能。除了社交情境外，在各种与奖励相关的情境中都记录到了50千赫兹的USV，包括含糖食物和饮料、可饮用乙醇以及滥用药物。本研究旨在直接比较其中几种行为情境在诱导和调节成年雄性大鼠50千赫兹USV发射方面的能力。使用两种社交条件（将未接触过的大鼠暴露于自然发情的雌性大鼠以及与同性笼伴团聚）和两种非社交条件（给予如水果圈或2%乙醇体积分数的可食用物质），我们分析了在6次刺激呈现过程中记录到的USV。仅发现雌性暴露条件下50千赫兹叫声频率显著高于基线水平，并且这种诱导在4次标准记录过程中变得更加明显。使用同性笼伴和两种可食用食物奖励并未引发高于基线水平的50千赫兹叫声。没有一种行为情境改变所发出的50千赫兹叫声的声学参数（峰值频率、持续时间和带宽）。在平衡记录过程中，与溶剂相比，用多巴胺拮抗剂氟哌啶醇预处理后，所有组的叫声均显著减少。非社交条件似乎以非颤音调频叫声为代价诱导出更大比例的平稳叫声，而社交条件下则相反。然而，食物奖励类型和社交情境类型分别对平稳叫声和颤音叫声的比例有影响。与对照组相比，获取含糖食物而非乙醇会诱导出更大比例的平稳叫声，雌性刺激而非笼伴刺激会诱导出更大比例的颤音叫声。
