Auditory cortical onset responses revisited .1. First-spike timing
Auditory cortical onset responses revisited .1. First-spike timing
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DOI：
10.1152/jn.1997.77.5.2616
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发表时间：
1997-05-01
影响因子：
2.5
通讯作者：
Heil, P
中科院分区：
文献类型：
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作者：
Heil, P
声音背景是显著的和行为相关的，大多数听神经元释放锁定在这种瞬间的尖峰。形成这种开始反应的声音的声学参数是未知的。本文分析了巴比妥类麻醉猫初级听皮层单个神经元对短纯音发生的时序。通过声压级、上升时间和上升函数(线性或余弦平方)的参数变化，得到峰值压力的时间历程。在音调开始时，峰值压力的变化率和峰值压力的加速度是系统变化的。对于给定频率和偏侧的余弦平方上升函数音调，任何神经元的平均第一峰波潜伏期都是出现在音调开始时的峰值压力最大加速度的不变和反函数。对于线性上升函数音调，潜伏期是峰值压力变化率的不变量和反函数。因此，潜伏期与上升时间或声压级本身无关。延迟加速功能。用余弦平方上升函数音调在不同刺激条件下(频率、偏侧度)获得的结果表明，来自任何给定神经元和跨神经元池的偏侧性具有惊人的相似形状。对于利用线性上升函数音调获得的峰值压力函数的潜伏期变化率也是如此。峰值压力函数变化的潜伏期-加速度比率可能因其范围和在坐标系中的位置不同而不同。位置的差异反映了神经元在最小潜伏期L-min以及S对加速度和峰值压力变化率(瞬时敏感性)的敏感性方面的差异，这是迄今为止尚未认识到的神经元特性，与放电阈值明显不同。L-分钟和S的估计值是通过将一个简单的函数与神经元的峰压潜伏期加速/变化率函数进行拟合而得到的，它们与上升函数无关。平均而言，L分钟随特征频率的增加而减小，但对于相同特征频率的神经元，其变化幅度较大。S对Cf的变化方式类似于猫的听力图，并且对于给定的神经元，随着频率的变化而变化。第一峰潜伏期的标准差大致与潜伏期与加速度/峰压变化率相关函数的斜率成正比。因此，SD随着平均潜伏期呈指数而不是线性地增加，并且其速度大约是线性上升函数音调的两倍，比例系数在整个神经元池中非常相似，并且对于两个上升函数来说都是相似的。最小标准差随L分钟数的增加呈非线性增加。这些发现表明S是外周起源的，并建立了潜伏期-加速度/峰压变化率函数的外周建立。由于这些功能在整个神经元池中的形状具有惊人的相似性，声音起始点将产生有序和可预测的第一峰时的时空模式，这些模式可以用于瞬时跟踪快速瞬变，并通过部分尺度不变的时态代码来表示瞬变特征。
Sound onsets are salient and behaviorally relevant, and most auditory neurons discharge spikes locked to such transients. The acoustic parameters of sound onsets that shape such onset responses are unknown. In this paper is analyzed the timing of spikes of single neurons in the primary auditory cortex of barbiturate-anesthetized cats to the onsets of tone bursts. By parametric variation of sound pressure level, rise time, and rise function (linear or cosine-squared), the time courses of peak pressure. rate of change of peak pressure, and acceleration of peak pressure during the tones' onsets were systematically varied. For cosine-squared rise function tones of a given frequency and laterality, any neuron's mean first-spike latency was an invariant and inverse function of the maximum acceleration of peak pressure occurring at tone onset. For linear rise function tones, latency was an invariant and inverse function of the rate of change of peak pressure. Thus latency is independent of rise time or sound pressure level per se. Latency-acceleration functions. obtained with cosine-squared rise function tones under different stimulus conditions (frequency, laterality from any given neuron and across the neuronal pool, were of strikingly similar shape. The same was true for latency - rate of change of peak pressure functions obtained with linear rise function tones. Latency - acceleration irate of change of peak pressure functions could differ in their extent and in their position within the coordinate system. The positional differences reflect neuronal differences in minimum latency L-min and in a sensitivity S to acceleration and rate of change of peak pressure (transient sensitivity), a hitherto unrecognized neuronal property that is distinctly different from firing threshold. Estimates of L-min and S, which were derived by fitting a simple function to the neuronal latency-accelcration/rate of change of peak pressure functions, were independent of rise function. On average, L-min decreased with increasing characteristic frequency (CF), but varied widely for neurons with the same CF. S varied with CF in a fashion similar to the cat's audiogram and, for a given neuron, varied with frequency. SD of first-spike latency was roughly proportional to the slope of the functions relating latency to acceleration/rate of change of peak pressure. Thus SD increased exponentially, rather than linearly, with mean latency, and did so at about twice the rate for linear than for cosine-squared rise function tones, The proportionality coefficients were quite similar across the neuronal pool and similar for both rise functions. Minimum SD increased nonlinearly with increasing L-min. These findings suggest a peripheral origin of S and a peripheral establishment of latency-acceleration/rate of change of peak pressure functions. Because of the striking similarity in the shapes of such functions across the neuronal pool, sound onsets will produce orderly and predictable spatiotemporal patterns of first-spike timing, which could be used to instantaneously track rapid transients and to represent transient features by partly scale-invariant temporal codes.