轴突延迟弥散决定神经元检测的是单个事件还是序列，并预测皮质柱直径
Axonal delay dispersion decides whether a neuron detects an event or a sequence, and predicts cortical column diameter
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中文总结 AI 辅助
该研究提出延迟特征框架，发现轴突延迟弥散度决定神经元检测事件或序列，其可设定编码极限，且与传导速度共同预测皮质柱直径，揭示了解剖参数对神经元计算的调控作用。
中文摘要 AI 辅助
皮质神经元的放电具有稀疏性，通常每个感觉窗口内的动作电位少于1个，这使得速率编码不足，时间编码成为必需。传导延迟将放电顺序转化为同步性，这一现象早已被证实，但尚未研究决定神经元检测哪类时间特征（一组同步输入或特定顺序的两组输入）的因素。我们提出了延迟特征框架，其中汇聚到树突分支的轴突传导延迟构成物理密钥：仅那些动作电位时间差能被延迟补偿的输入序列会同步到达，而通过钙平台阈值实现的同步检测会将这种同步转化为全或无的输出。在整合器神经元模型的模拟中，我们报告三项结果：第一，单个物理标量——延迟集的弥散度，可使种群从事件检测转变为顺序选择性序列检测。这种转变在随机延迟和连接性下是涌现的：在窄弥散度下不存在序列检测器，而序列检测器超过事件检测器的弥散度会以统计上与1无差异的斜率跟踪事件间隔，这将计算层面的区分映射到有髓和无髓投射的解剖学区分，使髓鞘化成为神经元计算内容的开关，而非仅速度的调节因子。第二，相同的弥散度设定了编码的极限：它限定了最长可编码间隔，并确定了约1毫秒的绝对时间容差，且对减慢的容忍度高于加快。第三，该毫秒窗口与水平传导速度共同预测皮质柱直径，且有直接测量的两个区域均落在该关系的预测范围内。因此，一个可解剖测量的参数即可决定神经元的检测内容及其可表征内容的极限。
英文摘要
Cortical neurons fire sparsely -- often fewer than one spike per sensory window -- making rate coding insufficient and temporal coding a necessity. That conduction delays convert firing order into synchrony is long established. What governs which class of temporal feature a neuron detects -- one volley of coincident input, or two in a particular order -- has not been examined. We propose a delay-signature framework in which the axonal conduction delays converging on a dendritic branch constitute a physical key: only input sequences whose spike-time differences the delays compensate arrive synchronously, and coincidence detection, via calcium plateau thresholds, converts that synchrony into an all-or-none output. In simulations of an integrator-neuron model we report three results. First, a single physical scalar -- the dispersion of the delay set -- moves a population from event detection to order-selective sequence detection. The transition is emergent under random delays and connectivity: at narrow dispersion sequence detectors do not exist, and the dispersion at which they overtake event detectors tracks the inter-event interval with a slope statistically indistinguishable from one. This maps a computational distinction onto the anatomical one between myelinated and unmyelinated projections, making myelination a switch on what a neuron computes, not only a regulator of speed. Second, the same dispersion sets the code's limits: it bounds the longest codable interval and fixes an absolute timing tolerance of about a millisecond, with slowing better tolerated than speeding. Third, that millisecond window and horizontal conduction velocity together predict cortical column diameter, and the two areas with direct measurements fall where the relation puts them. One anatomically measurable parameter thus sets what a neuron detects and the limits of what it can represent.
发表机构
- Department of Computer Science, Princeton University（普林斯顿大学计算机科学系）
机构由 AI 辅助整理，请以论文原文为准。
