The olfactory and endocrine systems have recently been shown to reciprocally shape the homeostatic processes of energy intake. As demonstrated in animal models, the individual’s metabolic state dynamically modulates how the olfactory bulb process odor stimuli using a range of endocrine signals. Here we aimed to determine whether the neural processing of odors in human olfactory bulb is modulated by metabolic state. Participants were exposed to food-associated odors, in separate sessions being hungry and sated, while neural responses from the olfactory bulb was obtained using electrobulbogram. We found significantly higher gamma power activity (51–100 Hz) in the OB’s response to odors during the Hunger compared to Sated condition. Specifically, EBG gamma power were elevated while hungry already at 100 ms after odor onset, thereby suggesting intra-bulbar modulation according to metabolic state. These results demonstrate that, akin to other animal models, hunger state affects OB activity in humans. Moreover, we show that the EBG method has the potential to measure internal metabolic states and, as such, could be used to study specificities in olfactory processing of individuals suffering from pathologies such as obesity or anorexia.

中文翻译：

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代谢状态调节人类嗅球气味的神经处理

最近研究表明，嗅觉和内分泌系统可以相互影响能量摄入的稳态过程。正如动物模型所证明的那样，个体的代谢状态动态地调节嗅球如何使用一系列内分泌信号处理气味刺激。在这里，我们的目的是确定人类嗅球中气味的神经处理是否受到代谢状态的调节。参与者暴露在与食物相关的气味中，在饥饿和饱足的不同阶段，同时使用球电图获得嗅球的神经反应。我们发现，与饱腹状态相比，饥饿状态下 OB 对气味的反应中的伽玛能量活动（51-100 Hz）明显更高。具体来说，在气味出现后 100 毫秒时，EBG 伽马功率在饥饿时升高，从而表明根据代谢状态进行球内调节。这些结果表明，与其他动物模型类似，饥饿状态会影响人类的 OB 活动。此外，我们表明 EBG 方法具有测量内部代谢状态的潜力，因此可用于研究患有肥胖或厌食症等疾病的个体嗅觉处理的特异性。