Subramanian Narayan, Leong Lee Min, Salemi Mokri Boukani Paria, Storace Douglas A
Department of Biological Science, Florida State University, Tallahassee, FL, United States.
Program in Neuroscience, Florida State University, Tallahassee, FL, United States.
Chem Senses. 2025 Jan 22;50. doi: 10.1093/chemse/bjae045.
Although animals can reliably locate and recognize odorants embedded in complex environments, the neural circuits for accomplishing these tasks remain incompletely understood. Adaptation is likely to be important as it could allow neurons in a brain area to adjust to the broader sensory environment. Adaptive processes must be flexible enough to allow the brain to make dynamic adjustments, while maintaining sufficient stability so that organisms do not forget important olfactory associations. Processing within the mouse olfactory bulb is likely involved in generating adaptation, although there are conflicting models of how it transforms the glomerular output of the mouse olfactory bulb. Here we performed 2-photon Ca2+ imaging from mitral/tufted glomeruli in awake mice to determine the time course of recovery from adaptation, and whether it acts broadly or selectively across the glomerular population. Individual glomerular responses, as well as the overall population odor representation were similar across imaging sessions. However, odor-concentration pairings presented with interstimulus intervals upwards of 30-s evoked heterogeneous adaptation that was concentration-dependent. We demonstrate that this form of adaptation is unrelated to variations in respiration, and olfactory receptor neuron glomerular measurements indicate that it is unlikely to be inherited from the periphery. Our results indicate that the olfactory bulb output can reliably transmit stable odor representations, but recent odor experiences can selectively shape neural responsiveness for upwards of 30 seconds. We propose that neural circuits that allow for non-uniform adaptation across mitral/tufted glomeruli could be important for making dynamic adjustments in complex odor environments.
尽管动物能够可靠地定位和识别复杂环境中嵌入的气味分子，但完成这些任务的神经回路仍未被完全理解。适应可能很重要，因为它可以使脑区中的神经元适应更广泛的感官环境。适应过程必须足够灵活，以便大脑能够进行动态调整，同时保持足够的稳定性，使生物体不会忘记重要的嗅觉关联。小鼠嗅球内的处理过程可能参与产生适应，尽管关于它如何转换小鼠嗅球的肾小球输出存在相互矛盾的模型。在这里，我们对清醒小鼠的二尖瓣/簇状肾小球进行了双光子Ca2+成像，以确定从适应中恢复的时间进程，以及它是在整个肾小球群体中广泛起作用还是选择性地起作用。在不同的成像过程中，单个肾小球反应以及总体气味表征都是相似的。然而，刺激间隔超过30秒呈现的气味-浓度配对会引发浓度依赖性的异质性适应。我们证明这种适应形式与呼吸变化无关，并且嗅觉受体神经元肾小球测量表明它不太可能从外周继承而来。我们的结果表明，嗅球输出可以可靠地传递稳定的气味表征，但最近的气味体验可以选择性地塑造神经反应性长达30秒以上。我们提出，允许二尖瓣/簇状肾小球之间进行非均匀适应的神经回路对于在复杂气味环境中进行动态调整可能很重要。
