Spike train encoding by regular-spiking cells of the visual cortex
Spike train encoding by regular-spiking cells of the visual cortex
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DOI：
10.1152/jn.1996.76.5.3425
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发表时间：
1996-11-01
影响因子：
2.5
通讯作者：
Movshon, JA
中科院分区：
文献类型：
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作者：
Carandini, M;Mechler, F;Movshon, JA
1.为了研究规则发放细胞将输入电流编码成输出锋电位序列的过程，我们在豚鼠视皮层脑片细胞内记录了阶跃、正弦和宽带噪声电流.当用正弦电流测量时，尖峰响应的频率调谐是显著带通的。频率在8 ~ 30 Hz之间，随刺激幅度和平均强度的增加而增加.宽带噪声电流的刺激大大提高了在低和高频率的尖峰响应的增益，产生一个基本上平坦的频率调谐0.1和130赫兹之间。平均尖峰响应的正弦电流表现出两个非线性：整流和尖峰同步。相比之下，在对宽带噪声刺激的平均响应中没有明显的非线性。尖峰响应的这些特性不存在于膜电位响应中。后者是大致线性的，并且它们的频率调谐是低通的，并且很好地拟合由电阻和电容并联组成的细胞膜的单室无源模型（RC电路）.为了解释尖峰响应，我们使用了由低通线性滤波器（RC电路）、整流非线性和高通线性滤波器组成的“三明治模型”。该模型由六个参数描述，并预测模拟放电率，而不是离散的尖峰。它对阶跃、正弦波和宽带噪声电流的发射率响应提供了令人满意的拟合。7.尖峰编码的属性是一致的时间非线性的视觉响应在V1，如响应频率调谐和刺激的对比度和带宽的延迟的依赖性。我们推测，在体内观察到的高频膜电位波动的作用之一可能是放大和线性化的反应较低，刺激相关的频率。
1. To study the encoding of input currents into output spike trains by regular-spiking cells, we recorded intracellularly from slices of the guinea pig visual cortex while injecting step, sinusoidal, and broadband noise currents.2. When measured with sinusoidal currents, the frequency tuning of the spike responses was markedly band-pass. The preferred frequency was between 8 and 30 Hz, and grew with stimulus amplitude and mean intensity.3. Stimulation with broadband noise currents dramatically enhanced the gain of the spike responses at low and high frequencies, yielding an essentially flat frequency tuning between 0.1 and 130 Hz.4. The averaged spike responses to sinusoidal currents exhibited two nonlinearities: rectification and spike synchronization. By contrast, no nonlinearity was evident in the averaged responses to broadband noise stimuli.5. These properties of the spike responses were not present in the membrane potential responses. The latter were roughly linear, and their frequency tuning was low-pass and well fit by a single-compartment passive model of the cell membrane composed of a resistance and a capacitance in parallel (RC circuit).6. To account for the spike responses, we used a ''sandwich model'' consisting of a low-pass linear filter (the RC circuit), a rectification nonlinearity, and a high-pass linear filter. The model is described by six parameters and predicts analog firing rates rather than discrete spikes. It provided satisfactory fits to the firing rate responses to steps, sinusoids, and broadband noise currents.7. The properties of spike encoding are consistent with temporal nonlinearities of the visual responses in V1, such as the dependence of response frequency tuning and latency on stimulus contrast and bandwidth. We speculate that one of the roles of the high-frequency membrane potential fluctuations observed in vivo could be to amplify and linearize the responses to lower, stimulus-related frequencies.