Laminar differences in taste coding: a circuit perspective

味道编码的层状差异：电路视角

基本信息

批准号：
9414019
负责人：
Alfredo Fontanini
金额：
$ 33.37万
依托单位：
STATE UNIVERSITY NEW YORK STONY BROOK
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-02-03 至 2021-01-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): How is gustatory information represented in the cortex? The answer to this question has been one of the mostly intensely debated topics in the field of gustatory neuroscience1-3. Two theories have been proposed and discussed over the past decades. According to the labeled-line theory the physiochemical identity of a gustatory stimulus is encoded by specific subsets of neurons, each of which is narrowly tuned to a single taste quality (i.e. salty, sweet, sour, bitter or umami)4-7. An alternative theory, the across-neuron pattern theory, postulates that taste coding relies on the combined activity of large ensembles of cortical neurons8. According to this theory, neurons do not need to be selective for specific taste qualities, instead each neuron can densely represent information by encoding multiple qualities3,9. Both theories are supported by experimental evidence. While a recent 2-photon calcium imaging study suggested the exclusive presence of narrowly tuned neurons in GC of anesthetized mice7; years of electrophysiological recordings in anesthetized and alert rodents demonstrate the presence of both narrowly tuned and densely coding neurons in GC10-13. Despite evidence that neurons using different coding strategies exist in GC, the debate is still polarized and no unifying view of taste coding in the cortex has emerged. The overarching goal of this proposal is to test the hypothesis that narrowly tuned and densely coding neurons reflect different stages of cortical processing. Specifically, we propose that the coding scheme varies depending on the cortical layers, with superficial layers (i.e., layers 2/3) featuring narroly tuned neurons and deep layers (i.e., layers 4 and 5) containing densely coding neurons. In addition, the experiments in this proposal aim at providing a mechanistic explanation for these differences, linking coding properties with laminar-dependent variations in inhibitory drive. The experiments will rely on a combination of sophisticated electrophysiological approaches to directly relate coding properties, balance between excitation and inhibition, and properties of local microcircuits. The framework of this grant is firmly grounded in the literature on cortical coding of sensory information14-17, and supported by our preliminary results, showing layer-specific differences in taste response properties and local connectivity. This research will help the field go beyond a dated debate and will move the discussion on taste coding toward a more circuit-oriented perspective. If successful this research will provide, for the first time, a unifid view of taste coding in cortical circuits of alert rodents.

描述（由适用提供）：皮质中如何表示味觉信息？这个问题的答案一直是味觉神经科学领域中最激烈的辩论主题之一。在过去的几十年中，已经提出并讨论了两种理论。根据标记的线理论，味觉刺激的物理身份是由特定的神经元子集编码的，神经元的特定子集都狭窄地调整为单个味道质量（即咸，甜，酸，苦，苦或鲜味）4-7。一种替代理论，即跨神经元模式理论，它假定味觉编码依赖于皮质神经元的大集合的合并活性。根据该理论，神经元不需要对特定的味道质量有选择性，而是通过编码多种质量3,9可以认为每个神经元是代表性的信息。这两种理论都得到了实验证据的支持。虽然最近的2光子钙成像研究表明，在麻醉小鼠的GC中存在狭窄调谐神经元的独家存在。在麻醉和警报啮齿动物中的多年电生理记录表明，在GC10-13中存在狭narl的调节和无缝的神经元。尽管有证据表明GC中存在使用不同编码策略的神经元，但辩论仍然是两极分化的，并且在皮质中没有统一的味觉编码观点。该提案的总体目标是检验以下假设：狭义调整且无用的编码神经元反映了皮质处理的不同阶段。具体而言，我们建议编码方案根据皮层层而变化，其浅层层（即2/3）具有狭窄的调谐神经元和深层（即4和5层），其中包含垂直编码神经元。此外，该提案中的实验旨在为这些差异提供机械解释，将编码属性与抑制性驱动中层层依赖性变化联系起来。实验将依靠复杂的电生理方法的组合来直接相关的编码特性，兴奋和抑制之间的平衡以及局部微电路的特性。该赠款的框架首先基于有关感官信息的皮质编码的文献14-17，并得到我们的初步结果的支持，显示了特定于层的味觉响应特性和局部连接性的差异。这项研究将有助于该领域超越过时的辩论，并将对口味编码的讨论转移到面向电路的视角。如果成功，这项研究将首次提供在警报啮齿动物的皮质回路中对味觉编码的统一观点。