QUANTITATIVE STUDIES OF STIMULUS CODING IN 1ST-ORDER VIBRISSA AFFERENTS OF RATS .2. ADAPTATION AND CODING OF STIMULUS PARAMETERS
QUANTITATIVE STUDIES OF STIMULUS CODING IN 1ST-ORDER VIBRISSA AFFERENTS OF RATS .2. ADAPTATION AND CODING OF STIMULUS PARAMETERS
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DOI：
10.3109/07367228309144543
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
WELKER, WI
中科院分区：
文献类型：
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作者：
GIBSON, JM;WELKER, WI
机械感觉神经元通常分为快速适应和缓慢适应。反应衰减（适应）进行了检查，在不断偏转的触须定量，可重复的，特设的措施。第五神经节的一阶触须激活的神经元表现出各种适应率，似乎是连续分布在快速和缓慢适应极端之间。刺激强度对适应率有显著影响。没有证据表明，一个二分法，在更慢的适应神经元，放电规律的基础上。阈值调谐曲线用于评估振动灵敏度。正弦刺激的最佳频率和1：1放电阈值均在2个数量级以上，且呈连续分布。一阶触须激活的传入表现出各种各样的反应模式，以恒速刺激。放电的模式变化作为时间的函数，在恒定速度（斜坡）偏转，并作为刺激速度的函数。虽然有关刺激参数的信息可以通过反应模式的几个特征中的任何一个来传达，但似乎很少有神经元充当任何特定刺激参数的纯编码器。用计算机拟合的方法，研究了鼻毛弯曲速度和振幅与放电率的关系。约有一半的观察率水平函数最好的描述幂函数，其余的最好的对数函数拟合。最佳拟合函数的参数变化范围广，连续，进一步强调了大鼠触须传入的编码特性的多样性。刺激幅度的率-水平曲线一般表现出饱和，有些是非单调的。没有一个被充分描述的对数函数或幂函数。
Mechanosensory neurons are often classified as either rapidly adapting or slowly adapting. Response decay (adaptation) was examined during constant deflection of the vibrissae with quantitative, repeatable, ad hoc measures. First-order vibrissa-activated neurons of the 5th ganglion exhibited a variety of adaptation rates that appear to be distributed continuously between the rapidly and slowly adapting extremes. Adaptation rate was influenced markedly by stimulus magnitude. No evidence was found for a dichotomy, within the more slowly adapting neurons, on the basis of discharge regularity. Threshold tuning curves were used to evaluate vibration sensitivity. Both the best frequencies and 1:1 discharge thresholds for sinusoidal stimulation ranged over 2 orders of magnitude, and were continuously distributed. First-order vibrissa-activated afferents exhibited a broad variety of response patterns to constant-velocity stimulation. The pattern of discharge varied both as a function of time, during constant-velocity (ramp) deflection, and as a function of stimulus velocity. Although information about the parameters of a stimulus may be conveyed by any of several features of the response pattern, it appeared that few if any neurons functioned as pure encoders of any particular stimulus parameter. The relationship between discharge rate and both velocity and amplitude of vibrissa deflection were examined with the aid of a computer-based curve-fitting procedure. About half the observed rate-level functions were best described by a power function; the remainder were best fit by a logarithmic function. The parameters of the best-fitting functions varied widely and continuously, emphasizing further the diversity of coding properties of the rat''s vibrissa afferents. Rate-level curves for stimulus magnitude generally exhibited saturation; some were nonmonotonic. None were described adequately by either a logarithmic function or a power function.