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===幂律尺寸分布===

===幂律尺寸分布===

 

The example avalanche shown has a size of 9 because this is the total number of electrodes that were driven over threshold. Avalanche sizes are distributed in a manner that is nearly fit by a [[power law]]. Due to the limited number of electrodes in the array, the power law begins to bend downward in a cutoff well before the array size of 60. But for larger electrode arrays, the power law is seen to extend much further.

 

这个片段说明，多通道数据可以被分解为没有活动的帧和至少有一个活动电极的帧，这些电极可能接收来自几个神经元的活动。由非活动帧包围的连续活动帧序列可以称为雪崩。所示的雪崩例子的大小为9，因为这是被驱动超过阈值的电极总数。雪崩大小的分布方式几乎符合[[幂律分布]]。由于阵列中的电极数量有限，幂律在阵列大小为60之前就开始向下弯曲切断，但是对于更大的电极阵列，可以看到幂律会延伸得更远。

[[Image:雪崩尺寸分布.jpg|thumb|500px|right|图4：雪崩尺寸分布。 A, Distribution of sizes from acute slice [[LFP]]s recorded with a 60 electrode array, plotted in log-log space. Actual data are shown in black, while the output of a [[Poisson model]] is shown in red. In the Poisson model, each electrode fires at the same rate as that seen in the actual data, but independently of all the other electrodes. Note the large difference between the two curves. The actual data follow a nearly straight line for sizes from 1- 35; after this point there is a cutoff induced by the electrode array size. The straight line is indicative of a power law, suggesting that the network is operating near the [[self-organized criticality|critical point]] (unpublished data recorded by W. Chen, C. Haldeman, S. Wang, A. Tang, J.M. Beggs). B, Avalanche size distribution for spikes can be approximated by a straight line over three orders of magnitude in probability, without a sharp cutoff as seen in panel A. Data were collected with a 512 electrode array from an acute cortical slice bathed in high potassium and zero magnesium (unpublished work of A. Litke, S. Sher, M. Grivich, D. Petrusca, S. Kachiguine, J.M. Beggs). Spikes were thresholded at -3 standard deviations and were not sorted. Data were binned at 1.2 ms to match the short interelectrode distance of 60 μm. Results similar to A and B are also obtained from cortical slice cultures recorded in culture medium.]]

[[Image:雪崩尺寸分布.jpg|thumb|500px|right|图4：雪崩尺寸分布。 A, Distribution of sizes from acute slice [[LFP]]s recorded with a 60 electrode array, plotted in log-log space. Actual data are shown in black, while the output of a [[Poisson model]] is shown in red. In the Poisson model, each electrode fires at the same rate as that seen in the actual data, but independently of all the other electrodes. Note the large difference between the two curves. The actual data follow a nearly straight line for sizes from 1- 35; after this point there is a cutoff induced by the electrode array size. The straight line is indicative of a power law, suggesting that the network is operating near the [[self-organized criticality|critical point]] (unpublished data recorded by W. Chen, C. Haldeman, S. Wang, A. Tang, J.M. Beggs). B, Avalanche size distribution for spikes can be approximated by a straight line over three orders of magnitude in probability, without a sharp cutoff as seen in panel A. Data were collected with a 512 electrode array from an acute cortical slice bathed in high potassium and zero magnesium (unpublished work of A. Litke, S. Sher, M. Grivich, D. Petrusca, S. Kachiguine, J.M. Beggs). Spikes were thresholded at -3 standard deviations and were not sorted. Data were binned at 1.2 ms to match the short interelectrode distance of 60 μm. Results similar to A and B are also obtained from cortical slice cultures recorded in culture medium.]]