Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
J Neurosci Methods. 2010 May 15;188(2):195-204. doi: 10.1016/j.jneumeth.2010.02.007. Epub 2010 Feb 12.
Drosophila olfactory aversive conditioning has served as a powerful model system with which to elucidate the molecular and neuronal mechanisms underlying memory formation. In the typical protocol, flies are exposed to a constant odor stream while receiving a pulsed electric shock in the conditioning tube of a manual apparatus. We have devised a simple, low-cost semi-automated conditioning apparatus that computationally controls the delivery of odor and shock. A semiconductor-based odor sensor is employed to monitor the change of odor concentration in the training tube. The system thus allows electric shocks to be precisely matched with odor concentration in the training tube. We found that short-term memory performance was improved with a pulsed odor flow protocol, in which odor is presented in short pulses, each paired with electric shock, rather than as a constant flow. The effect of pulsed odor flow might be ascribed to the phenomenon of 'conditioned approach', where approach toward an odor is induced when the electric shock is presented before odor pulse ends. Our data shows that the system is applicable to the study of olfactory memory formation and to the examination of conditioning parameters at a level of detail not practical with a manual apparatus.
果蝇嗅觉厌恶条件反射已成为一个强大的模式系统，可用于阐明记忆形成的分子和神经元机制。在典型的方案中，苍蝇在手动仪器的调节管中暴露于恒定的气味流，同时接受脉冲电刺激。我们设计了一种简单、低成本的半自动调节装置，通过计算来控制气味和冲击的传递。采用基于半导体的气味传感器来监测训练管中气味浓度的变化。因此，该系统允许电击与训练管中的气味浓度精确匹配。我们发现，使用脉冲气味流方案可以改善短期记忆性能，其中气味以短脉冲的形式呈现，每个脉冲都与电击配对，而不是作为恒定的气流。脉冲气味流的效果可能归因于“条件作用趋近”现象，即当电击在气味脉冲结束前呈现时，会诱导对气味的趋近。我们的数据表明，该系统适用于嗅觉记忆形成的研究，并可在手动仪器不实用的细节水平上检查调节参数。
