Vibratory adaptation of cutaneous mechanoreceptive afferents
Vibratory adaptation of cutaneous mechanoreceptive afferents
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DOI：
10.1152/jn.00002.2005
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发表时间：
2005-11-01
影响因子：
2.5
通讯作者：
Johnson, KO
中科院分区：
文献类型：
--
作者：
Bensmaïa, SJ;Leung, YY;Johnson, KO
本研究的目的是探讨延长阈上振动刺激对慢适应1型（SA 1），快适应（RA）和Pacinian（PC）传入的敏感性的影响。为此，开发了一种算法来跟踪传入绝对（I-0）和夹带（I-1）阈值随时间的变化。我们记录了传入反应的阈下振动测试刺激，这是交错的强烈的振动条件刺激在适应期的每个实验运行。从这些测量结果中，算法允许我们推断传入神经敏感性的变化。我们研究了影响适应的刺激参数，通过评估适应依赖于适应刺激的幅度和频率的程度。对于所有三种传入类型，I-0和I-1增加的适应频率和幅度。适应的程度似乎是独立的条件刺激在传入中引起的放电率。在分析中，我们区分了加性适应（其中I-0和I-1相等地移动）和倍增效应（其中I-1/I-0的比率保持不变）。RA阈值偏移几乎是完全相加的。SA 1阈值偏移接近于加性，而远离乘性（I-1阈值偏移是I-0偏移的两倍）。PC移位更难分类。我们使用了一个整合-激发模型来研究可能的神经机制。传感器增益的变化预示着I-0和I-1的倍增变化，因此排除了作为SA 1和RA适应机制的可能性。静息动作电位阈值的变化预示着I-0和I-1的相等的加性变化，因此很好地解释了RA适应。在相对不应期内不应度的变化预示着I-1的额外变化，如在SA 1纤维中观察到的变化。我们推断，适应是由增加尖峰阈值产生的离子流通过传感器通道在受体膜。在配套文件中，我们描述的时间过程中的振动适应和恢复SA 1，RA和PC纤维。
The objective of this study was to investigate the effects of extended suprathreshold vibratory stimulation on the sensitivity of slowly adapting type 1 (SA1), rapidly adapting ( RA), and Pacinian (PC) afferents. To that end, an algorithm was developed to track afferent absolute (I-0) and entrainment (I-1) thresholds as they change over time. We recorded afferent responses to periliminal vibratory test stimuli, which were interleaved with intense vibratory conditioning stimuli during the adaptation period of each experimental run. From these measurements, the algorithm allowed us to infer changes in the afferents' sensitivity. We investigated the stimulus parameters that affect adaptation by assessing the degree to which adaptation depends on the amplitude and frequency of the adapting stimulus. For all three afferent types, I-0 and I-1 increased with increasing adaptation frequency and amplitude. The degree of adaptation seems to be independent of the firing rate evoked in the afferent by the conditioning stimulus. In the analysis, we distinguished between additive adaptation ( in which I-0 and I-1 shift equally) and multiplicative effects ( in which the ratio I-1/I-0 remains constant). RA threshold shifts are almost perfectly additive. SA1 threshold shifts are close to additive and far from multiplicative (I-1 threshold shifts are twice the I-0 shifts). PC shifts are more difficult to classify. We used an integrate-and-fire model to study the possible neural mechanisms. A change in transducer gain predicts a multiplicative change in I-0 and I-1 and is thus ruled out as a mechanism underlying SA1 and RA adaptation. A change in the resting action potential threshold predicts equal, additive change in I-0 and I-1 and thus accounts well for RA adaptation. A change in the degree of refractoriness during the relative refractory period predicts an additional change in I-1 such as that observed for SA1 fibers. We infer that adaptation is caused by an increase in spiking thresholds produced by ion flow through transducer channels in the receptor membrane. In a companion paper, we describe the time-course of vibratory adaptation and recovery for SA1, RA, and PC fibers.