Liu Haixin, Fontanini Alfredo
Department of Neurobiology and Behavior and Graduate Program in Neuroscience, State University of New York at Stony Brook, Stony Brook, New York 11794.
Department of Neurobiology and Behavior and Graduate Program in Neuroscience, State University of New York at Stony Brook, Stony Brook, New York 11794
J Neurosci. 2015 Nov 25;35(47):15479-91. doi: 10.1523/JNEUROSCI.0839-15.2015.
The parvicellular portion of the ventroposteromedial nucleus (VPMpc) is the part of the thalamus that processes gustatory information. Anatomical evidence shows that the VPMpc receives ascending gustatory inputs from the parabrachial nucleus (PbN) in the brainstem and sends projections to the gustatory cortex (GC). Although taste processing in PbN and GC has been the subject of intense investigation in behaving rodents, much less is known on how VPMpc neurons encode gustatory information. Here we present results from single-unit recordings in the VPMpc of alert rats receiving multiple tastants. Thalamic neurons respond to taste with time-varying modulations of firing rates, consistent with those observed in GC and PbN. These responses encode taste quality as well as palatability. Comparing responses to tastants either passively delivered, or self-administered after a cue, unveiled the effects of general expectation on taste processing in VPMpc. General expectation led to an improvement of taste coding by modulating response dynamics, and single neuron ability to encode multiple tastants. Our results demonstrate that the time course of taste coding as well as single neurons' ability to encode for multiple qualities are not fixed but rather can be altered by the state of the animal. Together, the data presented here provide the first description that taste coding in VPMpc is dynamic and state-dependent.
Over the past years, a great deal of attention has been devoted to understanding taste coding in the brainstem and cortex of alert rodents. Thanks to this research, we now know that taste coding is dynamic, distributed, and context-dependent. Alas, virtually nothing is known on how the gustatory thalamus (VPMpc) processes gustatory information in behaving rats. This manuscript investigates taste processing in the VPMpc of behaving rats. Our results show that thalamic neurons encode taste and palatability with time-varying patterns of activity and that thalamic coding of taste is modulated by general expectation. Our data will appeal not only to researchers interested in taste, but also to a broader audience of sensory and systems neuroscientists interested in the thalamocortical system.
腹后内侧核小细胞部（VPMpc）是丘脑处理味觉信息的部分。解剖学证据表明，VPMpc接收来自脑干臂旁核（PbN）的味觉上行输入，并向味觉皮层（GC）发送投射。尽管在行为学啮齿动物中，PbN和GC中的味觉处理一直是深入研究的主题，但对于VPMpc神经元如何编码味觉信息却知之甚少。在此，我们展示了对清醒大鼠VPMpc进行单单位记录的结果，这些大鼠接受多种味觉刺激。丘脑神经元通过放电率的时变调制对味觉做出反应，这与在GC和PbN中观察到的情况一致。这些反应编码味觉质量以及适口性。比较对被动给予的味觉刺激或在提示后自我给予的味觉刺激的反应，揭示了一般预期对VPMpc中味觉处理的影响。一般预期通过调节反应动力学以及单个神经元编码多种味觉刺激的能力，导致味觉编码得到改善。我们的结果表明，味觉编码的时间进程以及单个神经元编码多种性质的能力不是固定不变的，而是可以被动物的状态改变。总之，此处呈现的数据首次描述了VPMpc中的味觉编码是动态的且依赖于状态。
在过去几年中，大量注意力致力于理解清醒啮齿动物脑干和皮层中的味觉编码。由于这项研究，我们现在知道味觉编码是动态的、分布式的且依赖于背景。遗憾的是，对于味觉丘脑（VPMpc）在行为学大鼠中如何处理味觉信息几乎一无所知。本手稿研究了行为学大鼠VPMpc中的味觉处理。我们的结果表明，丘脑神经元通过随时间变化的活动模式编码味觉和适口性，并且丘脑对味觉的编码受一般预期的调节。我们的数据不仅会吸引对味觉感兴趣的研究人员，也会吸引对丘脑皮层系统感兴趣的更广泛的感觉和系统神经科学家群体。
