The medial frontal cortex (MFC) in rodents emits rhythmic activity that is entrained to the animal's licking cycle during consumption and encodes the value of consumed fluids. These signals are especially prominent in the rostral half of the MFC. This region is located above an orbitofrontal region where mu-opioid receptors regulate intake and reversible inactivation reduces behavioral measures associated with the incentive value and palatability of liquid sucrose. Here, we examined the effects of reversible inactivation and stimulation of mu-opioid receptors in rostral MFC on behavior in an incentive contrast licking task. Adult male rats licked to receive access to liquid sucrose, which alternated between high (16%) and low (4%) values over 30 s periods. Bilateral infusion of muscimol reduced the total number of licks over the 30 min test sessions, the time spent actively consuming sucrose, and the ratio of licks for the higher and lower value fluids. Inactivation did not alter licking frequency or variability or microstructural measures such as the duration of licking bouts that are classically associated with the palatability of a liquid reward. Infusions of [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO; 1 μg/μL) at the same sites had inconsistent behavioral effects across different subjects. Our findings suggest that the rostral MFC has a distinct role in the control of consummatory behavior and contributes to persistent consumption and not to the expression of palatability. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

中文翻译：

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延髓内侧额叶皮层对于完成性行为的参与至关重要。

啮齿类动物的内侧额叶皮层 (MFC) 会发出有节奏的活动，这种活动会伴随动物在进食过程中的舔食周期，并对消耗的液体价值进行编码。这些信号在 MFC 的前半部尤为突出。该区域位于眶额区域上方，μ-阿片受体在该区域调节摄入量，可逆失活减少了与液体蔗糖的激励价值和适口性相关的行为措施。在这里，我们检查了在刺激性对比舔任务中，头端 MFC 中 mu-阿片受体的可逆失活和刺激对行为的影响。成年雄性大鼠通过舔舐获得液态蔗糖，蔗糖在 30 秒内在高 (16%) 和低 (4%) 值之间交替。双侧输注蝇蕈醇减少了 30 分钟测试期间的舔舐总数、主动消耗蔗糖所花费的时间，以及舔舐高价值和低价值液体的比例。失活不会改变舔频率或变异性或微观结构措施，例如通常与液体奖励的适口性相关的舔周期持续时间。输注 [d-Ala2,N -Me-Phe4、Gly5-ol]-脑啡肽（DAMGO；1 μg/μL）在同一位点对不同受试者的行为影响不一致。我们的研究结果表明，头侧 MFC 在控制完成行为方面具有独特的作用，并且有助于持续消费，而不是适口性的表达。（PsycInfo 数据库记录 (c) 2022 APA，保留所有权利）。