The mediodorsal thalamus is a higher order thalamic nucleus critical for many cognitive behaviors. Defined by its reciprocal connections with the prefrontal cortex, the mediodorsal thalamus receives strong projections from chemosensory cortical areas for taste and smell, gustatory cortex and piriform cortex. Recent studies indicate the mediodorsal thalamus is involved in experience-dependent chemosensory processes, including olfactory attention and discrimination and the hedonic perception of odor-taste mixtures. How novel and familiar chemosensory stimuli are represented within this structure remains unclear. Here, we compared the expression of c-Fos in the mediodorsal thalami of rats familiar with an odor, a taste, or an odor-taste mixture with those that sampled the stimuli for the first time. We found that familiar tastes or odor-taste mixtures induced significantly greater c-Fos expression in the mediodorsal thalamus than novel tastes or odor-taste mixtures, whereas novel odors induced greater c-Fos expression than familiar odors. These experience-dependent and modality-specific differences in c-Fos expression may relate to the behavioral relevance of the chemosensory stimulus, including odor neophobia. In a two-bottle brief-access preference task, rats preferred water to isoamyl acetate-odorized water over multiple days. However, after experience with isoamyl acetate mixed with sucrose (odor-taste mixture), the preference for water was eliminated. These findings demonstrate that experience with chemosensory stimuli modulates responses in the mediodorsal thalamus, suggesting this structure plays an integral role in communicating behaviorally relevant chemosensory information to higher order areas to guide food-related behaviors.

中文翻译：

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经验依赖的c-Fos表达在具有化学感应模式的Mediodorsal丘脑中变化。

Mediodorsal丘脑是高级丘脑核，对许多认知行为至关重要。通过与前额叶皮层的相互联系来定义，中嗅丘脑从化学感觉皮层区获得强烈的投射，以了解其味道和气味，味觉皮层和梨状皮层。最近的研究表明，中嗅丘脑参与了依赖于经验的化学感觉过程，包括嗅觉注意和辨别力以及对气味-味道混合物的享乐性感知。尚不清楚如何在这种结构内表示新颖和熟悉的化学感应刺激。在这里，我们将c-Fos在熟悉气味，味觉或气味-气味混合物的大鼠的中嗅丘脑中的表达与首次采样刺激的大鼠进行了比较。我们发现，熟悉的口味或气味-气味混合物在中嗅丘脑中诱导的c-Fos表达要比新颖的口味或气味-气味混合物显着更高，而新颖的气味比熟悉的气味诱导的c-Fos表达更高。c-Fos表达中的这些依赖于经验和特定于模式的差异可能与化学感应刺激的行为相关性有关，包括气味恐惧症。在两瓶简短访问偏好任务中，大鼠在数天内都喜欢水而不是乙酸异戊酯加味的水。然而，在乙酸异戊酯与蔗糖（气味-味道混合物）混合的经验之后，消除了对水的偏爱。这些发现表明，化学感应刺激的经验可调节中嗅丘脑的反应，