Department of Electrical Engineering, Columbia University, New York, NY, United States of America.
PLoS Comput Biol. 2023 Apr 21;19(4):e1011043. doi: 10.1371/journal.pcbi.1011043. eCollection 2023 Apr.
Recent advances in molecular transduction of odorants in the Olfactory Sensory Neurons (OSNs) of the Drosophila Antenna have shown that the odorant object identity is multiplicatively coupled with the odorant concentration waveform. The resulting combinatorial neural code is a confounding representation of odorant semantic information (identity) and syntactic information (concentration). To distill the functional logic of odor information processing in the Antennal Lobe (AL) a number of challenges need to be addressed including 1) how is the odorant semantic information decoupled from the syntactic information at the level of the AL, 2) how are these two information streams processed by the diverse AL Local Neurons (LNs) and 3) what is the end-to-end functional logic of the AL? By analyzing single-channel physiology recordings at the output of the AL, we found that the Projection Neuron responses can be decomposed into a concentration-invariant component, and two transient components boosting the positive/negative concentration contrast that indicate onset/offset timing information of the odorant object. We hypothesized that the concentration-invariant component, in the multi-channel context, is the recovered odorant identity vector presented between onset/offset timing events. We developed a model of LN pathways in the Antennal Lobe termed the differential Divisive Normalization Processors (DNPs), which robustly extract the semantics (the identity of the odorant object) and the ON/OFF semantic timing events indicating the presence/absence of an odorant object. For real-time processing with spiking PN models, we showed that the phase-space of the biological spike generator of the PN offers an intuit perspective for the representation of recovered odorant semantics and examined the dynamics induced by the odorant semantic timing events. Finally, we provided theoretical and computational evidence for the functional logic of the AL as a robust ON-OFF odorant object identity recovery processor across odorant identities, concentration amplitudes and waveform profiles.
最近在果蝇触角的嗅觉感觉神经元（OSN）中气味分子转导方面的进展表明，气味物体的身份与气味浓度波形呈乘法耦合。由此产生的组合神经代码是气味语义信息（身份）和句法信息（浓度）的混淆表示。为了提取触角叶（AL）中气味信息处理的功能逻辑，需要解决许多挑战，包括 1）在 AL 水平上，气味语义信息如何与句法信息解耦，2）这些信息流如何由不同的 AL 局部神经元（LNs）处理，以及 3）AL 的端到端功能逻辑是什么？通过分析 AL 输出的单通道生理学记录，我们发现投射神经元的反应可以分解为浓度不变的成分，以及两个瞬态成分，它们增强了正/负浓度对比度，表明气味物体的起始/结束时间信息。我们假设，在多通道环境中，浓度不变的成分是在起始/结束时间事件之间呈现的恢复气味身份向量。我们开发了一种称为差分归一化处理器（DNP）的触角叶 LN 通路模型，该模型可以稳健地提取语义（气味物体的身份）和表示气味物体存在/不存在的 ON/OFF 语义时间事件。对于具有尖峰 PN 模型的实时处理，我们表明 PN 的生物尖峰发生器的相空间为恢复气味语义的表示提供了直观的视角，并检查了气味语义时间事件引起的动力学。最后，我们为 AL 的功能逻辑提供了理论和计算证据，证明它是一种稳健的 ON-OFF 气味物体身份恢复处理器，可以在气味身份、浓度幅度和波形轮廓方面进行处理。
