Niewalda Thomas, Singhal Nidhi, Fiala André, Saumweber Timo, Wegener Stephanie, Gerber Bertram
Department of Genetics and Neurobiology, Universität Würzburg, Biozentrum, Am Hubland, D 970 74 Würzburg, Germany.
Chem Senses. 2008 Oct;33(8):685-92. doi: 10.1093/chemse/bjn037. Epub 2008 Jul 17.
Sodium and chloride need to be ingested and cannot be stored. Therefore, choice of habitat and diet as related to NaCl needs to be tightly regulated. We thus expect that the behavioral effects of salt are organized according to its concentration. Here, we comparatively "fingerprint" the reflex releasing (in choice and feeding experiments) versus the reinforcing effects of sodium chloride ("salt") in terms of their concentration dependencies, using larval Drosophila. Qualitatively, we find that the behavioral effects of salt in all 3 assays are similar: choice, feeding, and reinforcing effect all change from appetitive to aversive as concentration is increased. Quantitatively, however, the appetitive effects for choice and feeding share their optimum at around 0.02 M, whereas the dose-response curve for the reinforcing effect is shifted by more than one order of magnitude toward higher concentrations. Interestingly, a similar shift between these 2 kinds of behavioral effect is also found for sugars (Schipanski et al. 2008). Thus, for salt and for sugar, the sensory-to-motor system is more sensitive regarding immediate, reflexive behavior than regarding reinforcement. We speculate that this may partially be due to a dissociation of the sensory pathways signaling toward either reflexive behavior or internal reinforcement.
钠和氯需要摄入且无法储存。因此，与氯化钠需求相关的栖息地和饮食选择需要严格调控。我们因而预期盐的行为效应会依据其浓度来组织。在此，我们利用果蝇幼虫，比较了氯化钠（“盐”）在选择和进食实验中的反射释放效应与强化效应在浓度依赖性方面的差异。定性地说，我们发现在所有这三种试验中盐的行为效应是相似的：随着浓度增加，选择、进食和强化效应均从喜好变为厌恶。然而，定量来看，选择和进食的喜好效应在约0.02 M时达到最佳，而强化效应的剂量 - 反应曲线则向更高浓度方向偏移了一个多数量级。有趣的是，对于糖类也发现了这两种行为效应之间类似的偏移（施潘斯基等人，2008年）。因此，对于盐和糖而言，感觉运动系统对于即时反射行为比对于强化更为敏感。我们推测这可能部分是由于向反射行为或内部强化发出信号的感觉通路的分离。
