Brown Stacey L, Joseph Joby, Stopfer Mark
National Institute of Child Health and Human Development, US National Institutes of Health, Building 35, Room 3A-102, Bethesda, Maryland 20892, USA.
Nat Neurosci. 2005 Nov;8(11):1568-76. doi: 10.1038/nn1559. Epub 2005 Oct 16.
Sensory neural systems use spatiotemporal coding mechanisms to represent stimuli. These time-varying response patterns sometimes outlast the stimulus. Can the temporal structure of a stimulus interfere with, or even disrupt, the spatiotemporal structure of the neural representation? We investigated this potential confound in the locust olfactory system. When odors were presented in trains of nearly overlapping pulses, responses of first-order interneurons (projection neurons) changed reliably, and often markedly, with pulse position as responses to one pulse interfered with subsequent responses. However, using the responses of an ensemble of projection neurons, we could accurately classify the odorants as well as characterize the temporal properties of the stimulus. Further, we found that second-order follower neurons showed firing patterns consistent with the information in the projection-neuron ensemble. Thus, ensemble-based spatiotemporal coding could disambiguate complex and potentially confounding temporally structured sensory stimuli and thereby provide an invariant response to a stimulus presented in various ways.
感觉神经系统利用时空编码机制来表征刺激。这些随时间变化的反应模式有时会在刺激结束后持续存在。刺激的时间结构会干扰甚至破坏神经表征的时空结构吗？我们在蝗虫嗅觉系统中研究了这种潜在的混淆因素。当气味以几乎重叠的脉冲序列呈现时，一阶中间神经元（投射神经元）的反应会随着脉冲位置而可靠且常常显著地变化，因为对一个脉冲的反应会干扰后续反应。然而，利用投射神经元群体的反应，我们能够准确地对气味剂进行分类，并表征刺激的时间特性。此外，我们发现二阶跟随神经元的放电模式与投射神经元群体中的信息一致。因此，基于群体的时空编码可以消除复杂且可能混淆的时间结构感觉刺激的歧义，从而对以各种方式呈现的刺激提供不变的反应。
