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（由申请人提供）：味觉信息是如何在皮层中表达的？这个问题的答案一直是味觉神经科学领域最激烈争论的话题之一。在过去的几十年里，人们提出并讨论了两种理论。根据标记线理论，味觉刺激的生理化学特性是由特定的神经元子集编码的，每个神经元都被狭隘地调整为单一的味觉品质（即咸的、甜的、酸味、苦味或鲜味）4-7。特定的味觉品质，相反，每个神经元可以通过编码多种品质来密集地表示信息3,9，而最近的一项双光子钙成像研究表明，麻醉的 GC 中只存在窄调谐神经元。小鼠7；多年来对麻醉和警觉的啮齿类动物的电生理记录表明，GC10-13 中存在窄调和密集编码神经元，尽管有证据表明 GC 中存在使用不同编码策略的神经元，但争论仍然两极分化，并且对味觉没有统一的看法。该提案的总体目标是检验窄调和密集编码神经元反映皮层处理的不同阶段的假设。皮层，浅层（即第 2/3 层）具有窄调神经元，深层（即第 4 层和第 5 层）包含密集编码神经元。此外，本提案中的实验旨在为这些层提供机械解释。差异，将编码特性与抑制驱动的层流依赖性变化联系起来。这些实验将依赖于复杂的电生理学方法的组合来直接关联编码特性、兴奋和抑制之间的平衡以及局部特性。这项资助的框架牢固地扎根于感官信息皮质编码的文献14-17，并得到了我们初步结果的支持，显示了味觉响应特性和局部连接的层特定差异。这项研究将帮助该领域超越。这是一场过时的争论，并将把关于味觉编码的讨论转向更加以电路为导向的角度，如果这项研究成功，将首次提供警觉啮齿类动物皮层电路味觉编码的统一观点。