Interspike interval analyses reveal irregular firing patterns at short, but not long, intervals in rat head direction cells.
Interspike interval analyses reveal irregular firing patterns at short, but not long, intervals in rat head direction cells.
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DOI：
10.1152/jn.00649.2009
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发表时间：
2010-06
影响因子：
2.5
通讯作者：
J. Taube
中科院分区：
文献类型：
--
作者：
J. Taube
先前的研究表明，大鼠前背侧丘脑神经元的一个子集放电作为动物的头部方向（HD）在水平面上的功能，独立于动物的位置和行为。这些细胞在广泛的条件下具有一致的放电特性，并且当通过扬声器收听时，细胞放电表现出高度规律性。相比之下，对皮质细胞的锋电位间隔（ISI）分析发现，即使在恒定的刺激条件下，细胞放电也是不规则的。在这里，我们分析了前背侧丘脑的HD细胞，而大鼠觅食的食物颗粒，以确定他们的发射是定期或不定期。当动物的HD保持在细胞优选发射方向的± 6°内时，测量ISI。ISI具有高度变异性，平均变异系数（CV）为0.681。对于每个细胞，在偏离细胞首选方向± 24°的HD处的CV值与在细胞首选方向测量的系数相似。第二次记录显示细胞具有与第一次记录相似的变异系数，表明细胞尖峰的变异程度是每个细胞的特征性质。ISI与头部角速度或平移速度之间几乎没有相关性。从后下托和外侧乳头核的HD细胞中测量的ISI显示出较高的CV值。这些结果表明，尽管在他们的放电规律的外观，HD细胞，像皮质细胞，有不规则的ISI。与ISI观察到的不规则放电相反，在较长时间间隔内的分析表明HD细胞放电更规则，更接近于速率代码。这些研究结果具有吸引子网络模型的HD信号和模型提出来解释内嗅皮层的网格细胞信号的产生的影响。
Previous studies have shown that a subset of neurons in the rat anterodorsal thalamus discharge as a function of the animal's head direction (HD) in the horizontal plane, independent of the animal's location and behavior. These cells have consistent firing properties across a wide range of conditions and cell discharge appears highly regular when listened to through a loudspeaker. In contrast, interspike interval (ISI) analyses on cortical cells have found that cell firing is irregular, even under constant stimulus conditions. Here, we analyzed HD cells from the anterodorsal thalamus, while rats foraged for food pellets, to determine whether their firing was regular or irregular. ISIs were measured when the animal's HD was maintained within ± 6° of the cell's preferred firing direction. ISIs were highly variable with a mean coefficient of variation (CV) of 0.681. For each cell, the CV values at HDs ± 24° away from the cell's preferred direction were similar to the coefficient measured at the cell's preferred direction. A second recording session showed that cells had similar coefficients of variation as the first session, suggesting that the degree of variability in cell spiking was a characteristic property for each cell. There was little correlation between ISIs and angular head velocity or translational speed. ISIs measured in HD cells from the postsubiculum and lateral mammillary nuclei showed higher CV values. These results indicate that despite the appearance of regularity in their firing, HD cells, like cortical cells, have irregular ISIs. In contrast to the irregular firing observed for ISIs, analyses over longer time intervals indicated that HD cell firing was much more regular, more nearly resembling a rate code. These findings have implications for attractor networks that model the HD signal and for models proposed to explain the generation of grid cell signals in entorhinal cortex.