Ahissar E, Abeles M, Ahissar M, Haidarliu S, Vaadia E
Department of Neurobiology, The Weizmann Institute of Science, Rehovot, Israel.
Neuropharmacology. 1998 Apr-May;37(4-5):633-55. doi: 10.1016/s0028-3908(98)00068-9.
In this study, the necessary conditions, including those related to behavior, for lasting modifications to occur in correlated activity ('functional plasticity') were examined in the behaving monkey. Previously, in-vitro studies of neuronal plasticity yielded important information about possible mechanisms of synaptic plasticity, but could not be used to test their functionality in the intact, behaving brain. In-vivo studies usually focused on analysis of the responsiveness of single cells, but did not examine interactions between pairs of neurons. In this study, we combined the two approaches. This was achieved by recording extracellularly and simultaneously the spike activity of several single cells in the auditory cortex of the behaving monkey. The efficacy of neuronal interactions was estimated by measuring the correlation between firing times of pairs of single neurons. Using acoustic stimuli, a version of cellular conditioning was applied when the monkey performed an auditory discrimination task and when it did not. We found that: (i) functional plasticity is a function of the change in correlation, and not of the correlation or covariance per se, and (ii) functional plasticity depends critically on behavior. During behavior, an increase in the correlation caused a short-lasting strengthening of the neuronal coupling efficacy, and a decrease caused a short-lasting weakening. These findings indicate that neuronal plasticity in the auditory cortex obeys a version of Hebb's associative rule under strong behavioral control, as predicted by Thorndike's "Law of Effect".
在本研究中，我们在行为中的猴子身上研究了相关活动（“功能可塑性”）发生持久改变的必要条件，包括与行为相关的条件。此前，对神经元可塑性的体外研究得出了有关突触可塑性可能机制的重要信息，但无法用于测试其在完整的、有行为的大脑中的功能。体内研究通常侧重于分析单个细胞的反应性，但未研究神经元对之间的相互作用。在本研究中，我们将这两种方法结合起来。这是通过在行为中的猴子的听觉皮层中细胞外记录并同时记录几个单个细胞的放电活动来实现的。通过测量单个神经元对的放电时间之间的相关性来估计神经元相互作用的效能。使用声音刺激，在猴子执行听觉辨别任务时和未执行时应用了一种细胞条件作用形式。我们发现：（i）功能可塑性是相关性变化的函数，而不是相关性或协方差本身的函数，并且（ii）功能可塑性严重依赖于行为。在行为期间，相关性增加导致神经元耦合效能短暂增强，而相关性降低导致短暂减弱。这些发现表明，如桑代克的“效果律”所预测的那样，在强大的行为控制下，听觉皮层中的神经元可塑性遵循一种形式的赫布联想规则。
