Department of Biological Sciences and Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA.
Nat Neurosci. 2011 Feb;14(2):224-31. doi: 10.1038/nn.2707. Epub 2010 Dec 19.
Synapses made by local interneurons dominate the thalamic circuits that process signals traveling from the eye downstream. The anatomical and physiological differences between interneurons and the (relay) cells that project to cortex are vast. To explore how these differences might influence visual processing, we made intracellular recordings from both classes of cells in vivo in cats. Macroscopically, all receptive fields were similar, consisting of two concentrically arranged subregions in which dark and bright stimuli elicited responses of the reverse sign. Microscopically, however, the responses of the two types of cells had opposite profiles. Excitatory stimuli drove trains of single excitatory postsynaptic potentials in relay cells, but graded depolarizations in interneurons. Conversely, suppressive stimuli evoked smooth hyperpolarizations in relay cells and unitary inhibitory postsynaptic potentials in interneurons. Computational analyses suggested that these complementary patterns of response help to preserve information encoded in the fine timing of retinal spikes and to increase the amount of information transmitted to cortex.
局部中间神经元形成的突触主导着从眼睛下游传递信号的丘脑回路。中间神经元和投射到皮质的（中继）细胞在解剖和生理上存在巨大差异。为了探索这些差异如何影响视觉处理，我们在猫体内对这两类细胞进行了细胞内记录。宏观上，所有感受野都相似，由两个同心排列的亚区组成，其中暗和亮刺激引起相反的反应。然而，微观上，两种类型的细胞的反应模式相反。中继细胞中的兴奋性刺激驱动单个兴奋性突触后电位的冲动，而中间神经元则产生分级去极化。相反，抑制性刺激在中继细胞中诱发平滑的超极化，在中间神经元中诱发单位抑制性突触后电位。计算分析表明，这些互补的反应模式有助于保持视网膜尖峰精细定时编码的信息，并增加传递到皮质的信息量。
