Díaz-Quesada Marta, Maravall Miguel
Instituto de Neurociencias de Alicante, Universidad Miguel Hernández de Elche-Consejo Superior de Investigaciones Científicas, Campus de San Juan, 03550 Sant Joan d'Alacant, Spain.
J Neurosci. 2008 Jan 16;28(3):696-710. doi: 10.1523/JNEUROSCI.4931-07.2008.
Barrel cortex neuronal responses adapt to changes in the statistics of complex whisker stimuli. This form of adaptation involves an adjustment in the input-output tuning functions of the neurons, such that their gain rescales depending on the range of the current stimulus distribution. Similar phenomena have been observed in other sensory systems, suggesting that adaptive adjustment of responses to ongoing stimulus statistics is an important principle of sensory function. In other systems, adaptation and gain rescaling can depend on intrinsic properties; however, in barrel cortex, whether intrinsic mechanisms can contribute to adaptation to stimulus statistics is unknown. To examine this, we performed whole-cell patch-clamp recordings of pyramidal cells in acute slices while injecting stochastic current stimuli. We induced changes in statistical context by switching across stimulus distributions. The firing rates of neurons adapted in response to changes in stimulus statistics. Adaptation depended on the form of the changes in stimulus distribution: in vivo-like adaptation occurred only for rectified stimuli that maintained neurons in a persistent state of net depolarization. Under these conditions, neurons rescaled the gain of their input-output functions according to the scale of the stimulus distribution, as observed in vivo. This stimulus-specific adaptation was caused by intrinsic properties and correlated strongly with the amplitude of calcium-dependent slow afterhyperpolarizations. Our results suggest that widely expressed intrinsic mechanisms participate in barrel cortex adaptation but that their recruitment is highly stimulus specific.
桶状皮层神经元反应会适应复杂触须刺激统计特性的变化。这种适应形式涉及神经元输入 - 输出调谐函数的调整，使得它们的增益根据当前刺激分布的范围重新缩放。在其他感觉系统中也观察到了类似现象，这表明对持续刺激统计特性的适应性调整是感觉功能的一个重要原则。在其他系统中，适应和增益重新缩放可能取决于内在特性；然而，在桶状皮层中，内在机制是否能有助于适应刺激统计特性尚不清楚。为了研究这一点，我们在急性脑片中对锥体细胞进行全细胞膜片钳记录，同时注入随机电流刺激。我们通过在不同刺激分布之间切换来诱导统计背景的变化。神经元的放电率会根据刺激统计特性的变化而适应。适应取决于刺激分布变化的形式：仅对于使神经元保持在持续净去极化状态的整流刺激，才会出现类似体内的适应。在这些条件下，神经元会根据刺激分布的尺度重新缩放其输入 - 输出函数的增益，这与在体内观察到的情况一致。这种刺激特异性适应是由内在特性引起的，并且与钙依赖性慢后超极化的幅度密切相关。我们的结果表明，广泛表达的内在机制参与了桶状皮层的适应，但它们的启用具有高度的刺激特异性。
