OFF response transformations in the whisker/barrel system.
OFF response transformations in the whisker/barrel system.
复制标题
晶须/桶系统中的关闭响应变换。
DOI：
10.1152/jn.1994.72.1.392
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发表时间：
1994
影响因子：
2.5
通讯作者：
Simons,DJ
中科院分区：
文献类型：
--
作者：
Kyriazi,HT;Carvell,GE;Simons,DJ
1.以前的研究已经证明了显着的差异，在相对大小的开和关反应的神经元的须/桶系统。特别是，OFF反应在丘脑神经元中出乎意料地大。细胞外单位记录被用来检查是否不同的刺激发作和偏移之间的时间不同的影响关闭反应的神经元在三叉神经节，ventrobasal丘脑，和体感皮层第四层。控制胡须刺激被用来偏转个别触须在不同的方向。我们假设，部分是因为刺激开始引起的中枢抑制逐渐减弱，丘脑和皮层神经元的OFF反应，但不是三叉神经节细胞的大小会随着刺激持续时间的延长而增加，皮层的相对变化最大。2.关反应幅度丘脑和皮层神经元的人口增加，刺激持续时间从200到1,400毫秒。增加更大的非最佳偏转角。类似地，当刺激时间延长时，对持续时间短的刺激具有较小OFF反应的个体细胞倾向于显示成比例的更大增加。三叉神经节细胞的OFF反应在很大程度上不受刺激持续时间的影响。3.根据动作电位的时程，将桶神经元分为常规锋电位单位（RSU）和快速锋电位单位（FSU）。ON和OFF反应在前者较小，当刺激延长时，其OFF反应的百分比增加大于FSU。结果说明了丘脑输入信号的RSU，这被认为是兴奋性桶神经元的非线性变换，并扩展以前的研究结果之间的反应相似性丘脑皮质单位（TCU）和FSU，后者被认为是抑制。4.在皮层神经元中OFF反应抑制的时间过程表明，刺激起始引起具有两个组分的中枢抑制，一个是持续几十毫秒的强的组分，一个是持续几百毫秒的弱的组分。在胡须运动后，皮质和丘脑的背景活动水平降低>或= 1，800 ms。5.对于TCU，200-ms刺激比1，400-ms刺激更不可能引起OFF反应，但当反应发生时，它们由更大数量的时间更接近的尖峰组成。相比之下，RSU和FSU的200-ms刺激OFF响应显示出比它们的1400-ms响应更长的尖峰间期，每个响应的尖峰数量没有变化。（400字处截断摘要）
1. Previous studies have demonstrated marked differences in the relative sizes of ON and OFF responses of neurons in the whisker/barrel system. In particular, OFF responses are unexpectedly large in thalamic neurons. Extracellular unit recordings were used to examine whether varying the time between stimulus onset and offset differently affects OFF responses of neurons in the trigeminal ganglion, ventrobasal thalamus, and somatosensory cortical layer IV. Controlled whisker stimuli were used to deflect individual vibrissal hairs in different directions. We hypothesized that, in part because of the gradual waning of central inhibition evoked by stimulus onset, OFF responses of thalamic and cortical neurons but not trigeminal ganglion cells would increase in size with longer duration stimuli, with relative changes being greatest in the cortex. 2. OFF response magnitudes for thalamic and cortical neuronal populations increased as the stimulus duration was increased from 200 to 1,400 ms. Increases were greater at nonoptimal deflection angles. Similarly, individual cells having smaller OFF responses for the duration-short stimulus tended to display proportionately greater increases when the stimulus was lengthened. OFF responses of trigeminal ganglion cells were largely unaffected by stimulus duration. 3. Barrel neurons were subclassified as regular-spike units (RSUs) or fast-spike units (FSUs) on the basis of the time course of their action potentials. ON and OFF responses were smaller in the former and, when the stimulus was lengthened, percentage increases in their OFF responses were greater than those in FSUs. Results illustrate nonlinear transformations of the thalamic input signal by RSUs, which are presumed to be excitatory barrel neurons, and extend previous findings of response similarities between thalamocortical units (TCUs) and FSUs, the latter of which are thought to be inhibitory. 4. The time course of OFF response suppression in cortical neurons suggests that stimulus onset evokes central inhibition having two components, a potent one lasting several tens of milliseconds and a weaker one lasting many hundreds of milliseconds. Background activity levels in cortex and thalamus were diminished for> or = 1,800 ms after whisker movement. 5. For TCUs, 200-ms stimuli were less likely than 1,400-ms stimuli to elicit an OFF response, but when responses occurred they consisted of a greater number of spikes timed closer together. By contrast, the 200-ms stimulus OFF responses of the RSUs and FSUs displayed longer interspike intervals than did their 1400-ms responses, with no change in the number of spikes per response.(ABSTRACT TRUNCATED AT 400 WORDS)