Sandoz Jean-Christophe, Hammer Martin, Menzel Randolf
Freie Universität Berlin, Institut für Biologie-Neurobiologie, 14195 Berlin, Germany.
Learn Mem. 2002 Sep-Oct;9(5):337-48. doi: 10.1101/lm.50502.
In honeybees, Apis mellifera L., the proboscis extension reflex (PER) can be conditioned by associating an odor stimulus (CS) with a sucrose reward (US). As the neural structures involved in the detection and integration of CS and US are bilaterally symmetrical in the bee brain, we ask what respective role each brain side plays in the conditioning process. More specifically, the US normally used in conditioning experiments is the compound stimulation of the antennae (which triggers the PER) and of the proboscis (where bees lick the sucrose solution). Anatomically, the brain receives unilateral US input through each antenna, but bilateral input from the proboscis. By controlling each US component, we show that an antenna-US produces unilateral sensitization, whereas a proboscis-US or a compound-US induces bilateral sensitization. Bees can learn a unilateral odor CS with all three USs, but when a proboscis-US is used, new learning is inhibited on the contralateral side, owing to a possible US-preexposure effect. Furthermore, we show that the antenna-US induces both unilateral and bilateral reinforcement processes, whereas the proboscis-US produces only bilateral effects. Based on these data, we propose a functional model of the role of each brain side in processing lateralized CSs and USs in olfactory learning in honeybees.
在蜜蜂（西方蜜蜂，Apis mellifera L.）中，伸吻反射（PER）可以通过将气味刺激（条件刺激，CS）与蔗糖奖励（非条件刺激，US）相关联来进行条件化。由于参与检测和整合CS和US的神经结构在蜜蜂大脑中是双侧对称的，我们探究大脑的每一侧在条件化过程中分别发挥什么作用。更具体地说，在条件化实验中通常使用的非条件刺激是触角（触发PER）和吻（蜜蜂舔蔗糖溶液的部位）的复合刺激。从解剖学角度来看，大脑通过每根触角接收单侧非条件刺激输入，但从吻部接收双侧输入。通过控制每个非条件刺激成分，我们发现触角-非条件刺激产生单侧敏感化，而吻-非条件刺激或复合-非条件刺激诱导双侧敏感化。蜜蜂可以用所有三种非条件刺激学习单侧气味条件刺激，但当使用吻-非条件刺激时，由于可能的非条件刺激预暴露效应，对侧的新学习受到抑制。此外，我们表明触角-非条件刺激诱导单侧和双侧强化过程，而吻-非条件刺激仅产生双侧效应。基于这些数据，我们提出了一个功能模型，阐述了蜜蜂嗅觉学习中大脑每一侧在处理侧化的条件刺激和非条件刺激时所起的作用。
