Neuronal mechanisms of merging multi-modal information and modulation through experience

多通道整合及其神经元计算是感觉知觉的核心，因为环境总是由不同的感觉通道组成。大脑如何设法提取相关特征并将单一模式组合成共同的感知尚不完全清楚。我的目标是扩大我们对多模式整合和经验依赖型感觉知觉背后的神经机制的有限理解。由于蜜蜂的感觉生态学和神经生物学特性，蜜蜂是研究多通道整合神经元原理的良好模型，尤其是嗅觉-视觉整合对单通道知觉的影响。该项目的重点是蘑菇体输出神经元(MBON)，因为从神经元电路的角度来看，这些神经元代表了蜜蜂嗅觉-视觉会聚的第一个水平。我已经建立了一个记录装置，允许记录在单色光和单一气味成分刺激期间的多个小时的MBON活动。初步数据显示，记录的MBON中约50%对两种方式(气味和光线)都有反应。我假设这些MBON包括多模式整合的神经元底物及其经验依赖的调制，这将在拟议的项目中描述。作为第一步，气味和光刺激将以单峰和多峰(复合)方式呈现，并将分析MBON活动。这一结果将揭示嗅觉-视觉会聚后神经编码的原理。接下来，我将研究气味-光化合物与奖励的关联如何影响单一成分(气味和光)的神经元表示。为了验证这一点，将进行在蜜蜂身上建立良好的经典条件作用实验。蜜蜂将被训练将嗅觉-视觉复合刺激与奖励联系起来。随后，我们将测试蜜蜂是只对化合物有反应，还是单一刺激成分(气味和光线)也可能触发反应。在最后一步中，我将结合经典的嗅觉-视觉条件作用(行为)和MBON记录(电生理学)，并分析与嗅觉-视觉化合物相比，共同的奖赏关联如何影响单个成分的神经表征。使用多个单元的长期记录，结合蜜蜂的经典条件作用实验，我已经可以证明MBON编码气味奖赏关联。此外，最近我发现，除了气味认同之外，气味奖赏关联还包括关于触角刺激一侧的信息，增加了一个空间维度。因此，MBON整合了奖赏相关刺激情境的不同特征。通过计划中的项目，我期待着我们对多模式整合及其经验依赖性调制背后的神经元机制的理解取得重大进展。

Multi-modal integration and its neuronal computation are central to sensory perception as the environment always comprises a composition of different sensory modalities. How brains manage to extract the relevant features and combine single modalities to a common percept is yet not fully understood. My goal is to extend our rather limited understanding on the neural mechanisms underlying multi-modal integration and experience dependent sensory perception. Due to its sensory ecology and neurobiology the honeybee represents a favorable model to investigate neuronal principles of multi-modal integration, in particular influences of olfactory-visual integration on single-modality perception. The project is focused on mushroom body output neurons (MBON) as from a neuronal circuit perspective these neurons represent the first level of olfactory-visual convergence in honeybees. I have set up a recording rig allowing for registration of MBON activity over many hours during stimulation with monochromatic light and single odor components. Preliminary data show that ~50% of the recorded MBONs respond to both modalities (odor and light). I hypothesize that these MBONs comprise a neuronal substrate for multi-modal integration and its experience dependent modulation, which will be characterized in the proposed project. As an initial step defined odor and light stimuli will be presented in a unimodal as well as in a multi-modal (compound) fashion and the MBON activity will be analyzed. The results will uncover principals of neural coding after olfactory-visual convergence. Next, I will investigate how the association of an odor-light compound with a reward influences the neuronal representations of the single components (odor and light). To test this, classical conditioning experiments that are well established in honeybees will be performed. Bees will be trained to associate an olfactory-visual compound stimulus with a reward. Subsequently, we will test if the bees respond to the compound only or if the single stimulus components (odor and light) may as well trigger a response. In a final step I will combine classical olfactory-visual conditioning (behavior) with MBON recordings (electrophysiology) and analyze how the common reward association affects the neural representation of the single components compared to the olfactory-visual compound. Using multi-unit long term recordings in combination with classical conditioning experiments in honeybees I could already show that MBONs encode the odor reward association. Moreover, recently I found that in addition to the odor identity the odor reward association includes the information about the antennal stimulation side, adding a spatial dimension. Thus, MBONs integrate different features of the reward associated stimulus situation. With the planned project I expect significant advance in our understanding of the neuronal mechanisms underlying multimodal integration and its experience dependent modulation.