Pelz C, Gerber B, Menzel R
Institut für Neurobiologie, Freie Universität Berlin, Germany.
J Exp Biol. 1997 Feb;200(Pt 4):837-47. doi: 10.1242/jeb.200.4.837.
Stimulus intensity is an important determinant for perception, learning and behaviour. We studied the effects of odorant concentration on classical conditioning involving odorants and odorant-mechanosensory compounds using the proboscis-extension reflex in the honeybee. Our results show that high concentrations of odorant (a) support better discrimination in a feature-positive task using rewarded odorant-mechanosensory compounds versus unrewarded mechanosensory stimuli, (b) have a stronger capacity to overshadow learning of a simultaneously trained mechanosensory stimulus, and (c) induce better memory consolidation. Furthermore, honeybees were trained discriminatively to two different concentrations of one odorant. Honeybees are not able to solve this task when presented with rewarded low versus unrewarded high concentrations. Taken together, our results suggest that high concentrations of odorant support stronger associations (are more 'salient') than low concentrations. Our results, however, do not indicate that honeybees can treat two different concentrations of one odorant as qualitatively different stimuli. These findings fill a gap in what is known about honeybee olfactory learning and are a first step in relating behaviour to recent advances in the physiological analysis of coding for odorant concentration in honeybees.
刺激强度是感知、学习和行为的重要决定因素。我们利用蜜蜂的伸吻反射，研究了气味浓度对涉及气味剂和气味-机械感觉化合物的经典条件反射的影响。我们的结果表明，高浓度的气味剂：(a) 在使用奖励性气味-机械感觉化合物与无奖励的机械感觉刺激的特征阳性任务中，能更好地支持辨别；(b) 对同时训练的机械感觉刺激的学习具有更强的遮蔽能力；(c) 能诱导更好的记忆巩固。此外，对蜜蜂进行了针对一种气味剂两种不同浓度的辨别训练。当呈现奖励性低浓度与无奖励高浓度时，蜜蜂无法完成这项任务。综合来看，我们的结果表明，高浓度的气味剂比低浓度能支持更强的关联（更“显著”）。然而，我们的结果并未表明蜜蜂能将一种气味剂的两种不同浓度视为质上不同的刺激。这些发现填补了关于蜜蜂嗅觉学习已知知识的空白，并且是将行为与蜜蜂气味浓度编码生理分析的最新进展联系起来的第一步。
