PERIODICITY AND DIRECTIONALITY IN THE PROPAGATION OF EPILEPTIFORM DISCHARGES ACROSS NEOCORTEX
PERIODICITY AND DIRECTIONALITY IN THE PROPAGATION OF EPILEPTIFORM DISCHARGES ACROSS NEOCORTEX
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DOI：
10.1152/jn.1988.60.5.1695
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发表时间：
1988-11-01
影响因子：
2.5
通讯作者：
CONNORS, BW
中科院分区：
文献类型：
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作者：
CHERVIN, RD;PIERCE, PA;CONNORS, BW
1.癫痫样放电的水平传播已被研究在高浓度的荷包牡丹碱甲碘，抑制性递质γ-氨基丁酸（GABA）的拮抗剂处理的新皮层切片。检查的皮质区是：初级躯体感觉（SmI）和运动（MI），以及大鼠的初级（17区）和次级（18区）视觉区，猫的17区。在所有这些领域的电刺激诱发单一的，所有或没有阵发性场电位（PFP），传播跨越整个宽度的切片没有递减。2. PFP传播的速度约为0.06-0.09米/秒时，平均数毫米的皮质距离。PFP传播在切片上的两个方向上同样良好地发生。3.在更高的空间分辨率（100-180微米的间隔）的PFP传播的测量结果显示，速度是不均匀的大鼠SmI，大鼠区18和猫区17，而是变化了许多倍的水平位置的变化。在这些地区的皮质，传播模式是空间周期性的功率谱显示，占主导地位的空间频率集中在约1毫米-1，与2毫米-1以上的贡献可以忽略不计。偶尔PFP传播是不连续的，跳过一个小区域的皮质和到达远端之前，传播到更近端的区域。4.在那些具有周期性传播模式的皮质中，PFP速度也具有很强的方向依赖性。在同一条皮层上以相反方向测量的传播模式显示出相似的周期性，但在许多切片中，它们是负相关的，即，在一个方向上的传播模式与在另一个方向上的传播模式相比是反相的。5.相反，大鼠17区中心的传播速度相对恒定，没有方向性。然而，在17和18区边界附近，PFP速度突然变化，并在18区内成为周期性的。同样，大鼠MI内的速度比相邻的SmI更恒定，方向性更弱。6. PFP的传播速度的模式往往是空间周期性的，方向不对称的，并依赖于皮层区域。我们认为，周期性图案反映了系统的水平兴奋性连接的长度或密度的变化。或者，或者同时，周期性可能来自于在解剖学上观察到的新皮层许多区域的内在连接的斑块分布。
1. The horizontal propagation of epileptiform discharges has been studied in slices of neocortex treated with high concentrations of bicuculline methiodide, an antagonist of the inhibitory transmitter gamma-aminobutyric acid (GABA). The cortical areas examined were: primary somatosensory (SmI) and motor (MI), and primary (area 17) and secondary (area 18) visual areas of rats, and area 17 of cats. In all of these areas an electrical stimulus evoked single, all-or-none paroxysmal field potentials (PFPs) that propagated across the entire width of the slice without decrement. 2. The velocity of PFP propagation was approximately 0.06-0.09 m/s when averaged over cortical distances of several millimeters. PFP propagation occurred equally well in both directions across a slice. 3. Measurement of PFP propagation at higher spatial resolution (100-180 micron intervals) revealed that velocity was not homogeneous within rat SmI, rat area 18 and cat area 17, but instead varied manyfold as horizontal position changed. In these areas of cortex, propagation patterns were spatially periodic; power spectra reveal that the dominant spatial frequencies were centered about 1 mm-1, with negligible contributions above 2 mm-1. Occasionally PFP propagation was discontinuous, skipping over a small region of cortex and arriving distally before propagating into the more proximal region. 4. In those cortices with periodic propagation patterns, PFP velocity was also strongly direction-dependent. Propagation patterns measured in opposite directions across the same strip of cortex displayed similar periodicities, but in many slices they were negatively correlated, i.e., the propagation pattern in one direction was antiphasic compared to that in the other direction. 5. In contrast, propagation velocity across the center of area 17 of the rat was relatively constant and not directional. Near the boundaries of areas 17 and 18, however, PFP velocity changed abruptly and became periodic within area 18. Similarly, velocity within rat MI was more constant and less directional than in the adjacent SmI. 6. The patterns of PFP propagation velocity are often spatially periodic, directionally asymmetric, and depend upon cortical area. We suggest that the periodic patterns reflect systematic variations in the length or density of horizontal excitatory connections. Alternatively, or concurrently, periodicities could arise from the patchy distributions of intrinsic connections that have been observed anatomically in many areas of neocortex.