Filla Ina, Menzel Randolf
Institute of Neurobiology, Freie Universität Berlin, Berlin, Germany.
Institute of Neurobiology, Freie Universität Berlin, Berlin, Germany
J Neurophysiol. 2015 Sep;114(3):2005-14. doi: 10.1152/jn.00776.2014. Epub 2015 Jul 29.
Multimodal GABA-immunoreactive feedback neurons in the honeybee brain connecting the output region of the mushroom body with its input are expected to tune the input to the mushroom body in an experience-dependent way. These neurons are known to change their rate responses to learned olfactory stimuli. In this work we ask whether these neurons also transmit learned attentional effects during multisensory integration. We find that a visual context and an olfactory cue change the rate responses of these neurons after learning according to the associated values of both context and cue. The learned visual context promotes attentional response selection by enhancing olfactory stimulus valuation at both the behavioral and the neural level. During a rewarded visual context, bees reacted faster and more reliably to a rewarded odor. We interpreted this as the result of the observed enhanced neural discharge toward the odor. An unrewarded context reduced already low rate responses to the unrewarded odor. In addition to stimulus valuation, these feedback neurons generate a neural error signal after an incorrect behavioral response. This might act as a learning signal in feedback neurons. All of these effects were exclusively found in trials in which the animal prepares for a motor response that happens during attentional stimulus selection. We discuss possible implications of the results for the feedback connections of the mushroom body.
蜜蜂大脑中连接蘑菇体输出区域与其输入区域的多模态γ-氨基丁酸免疫反应性反馈神经元，有望以经验依赖的方式调节进入蘑菇体的输入。已知这些神经元会改变其对已学习嗅觉刺激的速率反应。在这项研究中，我们探究这些神经元在多感官整合过程中是否也传递已学习的注意力效应。我们发现，视觉背景和嗅觉线索在学习后会根据背景和线索的相关值改变这些神经元的速率反应。已学习的视觉背景通过在行为和神经层面增强嗅觉刺激评估，促进注意力反应选择。在有奖励的视觉背景下，蜜蜂对有奖励的气味反应更快且更可靠。我们将此解释为观察到的对该气味增强的神经放电的结果。无奖励的背景会降低对无奖励气味本就较低的速率反应。除了刺激评估外，这些反馈神经元在行为反应错误后会产生神经误差信号。这可能在反馈神经元中充当学习信号。所有这些效应仅在动物为注意力刺激选择期间发生的运动反应做准备的试验中被发现。我们讨论了这些结果对蘑菇体反馈连接的可能影响。
