Sherman S M
Department of Neurobiology, State University of New York, Stony Brook 11794-5230, USA.
Vis Neurosci. 1996 Mar-Apr;13(2):205-13. doi: 10.1017/s0952523800007446.
Relay cells of the lateral geniculate nucleus, like those of other thalamic nuclei, manifest two distinct response modes, and these represent two very different forms of relay of information to cortex. When relatively hyperpolarized, these relay cells respond with a low threshold Ca2+ spike that triggers a brief burst of conventional action potentials. These cells switch to tonic mode when depolarized, since the low threshold Ca2+ spike, being voltage dependent, is inactivated at depolarized levels. In this mode they relay information with much more fidelity. This switch can occur under the influence of afferents from the visual cortex or parabrachial region of the brain stem. It has been previously suggested that the tonic mode is characteristic of the waking state while the burst mode signals an interruption of the geniculate relay during sleep. This review surveys the key properties of these two response modes and discusses the implications of new evidence that the burst mode may also occur in the waking animal.
外侧膝状体核的中继细胞，与其他丘脑核的细胞一样，表现出两种不同的反应模式，而这两种模式代表了将信息传递至皮层的两种截然不同的形式。当相对超极化时，这些中继细胞会以低阈值Ca2+ 尖峰做出反应，该尖峰触发一阵短暂的传统动作电位。当细胞去极化时，它们会切换到紧张性模式，因为低阈值Ca2+ 尖峰依赖电压，在去极化水平时会失活。在这种模式下，它们传递信息的保真度更高。这种转换可能发生在来自视皮层或脑干臂旁区域的传入神经的影响下。此前有人提出，紧张性模式是清醒状态的特征，而爆发模式则表明睡眠期间膝状体中继中断。这篇综述概述了这两种反应模式的关键特性，并讨论了新证据的意义，即爆发模式也可能出现在清醒动物中。
