Anticipatory time intervals of head-direction cells in the anterior thalamus of the rat: Implications for path integration in the head-direction circuit
Anticipatory time intervals of head-direction cells in the anterior thalamus of the rat: Implications for path integration in the head-direction circuit
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DOI：
10.1152/jn.1997.78.1.145
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发表时间：
1997-07-01
影响因子：
2.5
通讯作者：
Sharp, PE
中科院分区：
文献类型：
--
作者：
Blair, HT;Lipscomb, BW;Sharp, PE
头向细胞是一种神经元，它在水平面上指示老鼠的方向。丘脑前部的头部方向细胞是预期的，因此它们的放电频率与大鼠未来的头部方向的关系比与现在或过去的头部方向的关系更好。我们记录了自由运动大鼠丘脑前部头部方向细胞的单个活动。我们测量了每个细胞预测大鼠未来头部方向的时间间隔，我们称之为细胞的预期时间间隔（ATI）。丘脑前部的头部方向细胞预测大鼠未来的头部方向的平均ATI大约为17毫秒。然而，不同的丘脑前细胞一致地通过不同的ATIs预测未来的头部方向，范围在0到50 ms之间。我们发现丘脑前侧头向细胞的ATI与细胞定向调节功能的几个参数相关。首先，具有长ATIs的细胞有时在其定向调谐功能中出现两个峰，而具有短ATIs的细胞总是只有一个峰。其次，细胞的ATI与细胞的峰值放电速率呈负相关，因此具有较长ATI的细胞的放电速率比具有较短ATI的细胞慢。第三，细胞的ATI与其定向调谐函数的宽度相关，因此具有较长ATI的细胞比具有较短ATI的细胞具有更宽的调谐宽度。细胞的ATI与其方向调谐参数之间的这些关系不能通过调谐函数的人为拓宽来解释，这种情况发生在与未来（而不是现在）头部方向相关的细胞中。我们发现，当大鼠的头部转动时，丘脑前头向细胞调节功能的形状会系统性地发生变化，变得更高、更窄和歪斜。这种调节功能形状的系统性变化可能是导致前丘脑细胞有效预测大鼠未来头部方向的原因。我们提出了一种神经回路机制来解释我们在实验中观察到的放电行为，并讨论了该回路如何作为神经系统的功能组件，用于大鼠定向方向的路径整合。
Head-direction cells are neurons that signal a rat's directional heading in the horizontal plane. Head-direction cells in the anterior thalamus are anticipatory, so that their firing rate is better correlated with the rat's future head direction than with the present or past head direction. We recorded single-unit activity from head-direction cells in the anterior thalamus of freely moving rats. We measured the time interval by which each individual cell anticipated the rat's future head direction, which we refer to as the cell's anticipatory time interval (ATI). Head-direction cells in the anterior thalamus anticipated the rat's future head direction by an average ATI of similar to 17 ms. However, different anterior thalamic cells consistently anticipated the future head direction by different ATIs ranging between 0 and 50 ms. We found that the ATI of an anterior thalamic head-direction cell was correlated with several parameters of the cell's directional tuning function. First, cells with long ATIs sometimes appeared to have two peaks in their directional tuning function, whereas cells with short ATIs always had only one peak. Second, the ATI of a cell was negatively correlated with the cell's peak firing rate, so that cells with longer ATIs fired at a slower rate than cells with shorter ATIs. Third, a cell's ATI was correlated with the width of its directional tuning function, so that cells with longer ATIs had broader tuning widths than cells with shorter ATIs. These relationships between a cell's ATI and its directional tuning parameters could not be accounted for by artifactual broadening of the tuning function, which occurs for cells that fire in correlation with the future (rather than present) head direction. We found that when the rat's head is turning, the shape of an anterior thalamic head direction cell's tuning function changes in a systematic way, becoming taller, narrower, and skewed. This systematic change in the shape of the tuning function may be what causes anterior thalamic cells to effectively anticipate the rat's future head direction. We propose a neural circuit mechanism to account for the firing behavior we have observed in our experiments, and we discuss how this circuit might serve as a functional component of a neural system for path integration of the rat's directional heading.