Gerschenfeld H M, Piccolino M, Neyton J
J Exp Biol. 1980 Dec;89:177-92. doi: 10.1242/jeb.89.1.177.
Light stimulation of the periphery of the receptive field of turtle cones can evoke both transient and sustained increases of the cone Ca2+ conductance, which may become regenerative. Such increase in the cone Ca2+ conductance evoked by peripheral illumination results from the activation of a polysynaptic pathway involving a feed-back connexion from the L-horizontal cells (L-HC) to the cones. Thus the hyperpolarization of a L-HC by inward current injection can evoke a Ca2+ conductance increase in neighbouring cones. The cone Ca2+ channels thus activated are likely located at its synaptic endings and probably intervene in the cone transmitter release. Therefore the feed-back connexion between L-HC and cones by modifying the Ca2+ conductance of cones could actually modulate the transmitter release from cone synapses. Such feed-back modulation of cone synapses plays a role in the organization of the colour-coded responses of the chromaticity type-horizontal cells and probably of other second order neurones, post-synaptic to the cones. The mechanisms operating the feed-back connexion from L-HC to cones are discussed.
对龟视锥细胞感受野周边进行光刺激，可引起视锥细胞Ca2+电导的瞬态和持续增加，这种增加可能会变成再生性的。周边光照引起的视锥细胞Ca2+电导增加，是由一条多突触通路的激活所致，该通路涉及从L水平细胞（L-HC）到视锥细胞的反馈连接。因此，通过内向电流注入使L-HC超极化，可引起相邻视锥细胞的Ca2+电导增加。如此激活的视锥细胞Ca2+通道可能位于其突触末梢，可能参与视锥细胞递质释放。因此，L-HC与视锥细胞之间的反馈连接通过改变视锥细胞的Ca2+电导，实际上可能调节视锥细胞突触的递质释放。视锥细胞突触的这种反馈调节，在色度型水平细胞以及可能在视锥细胞突触后其他二级神经元的颜色编码反应的组织中发挥作用。本文讨论了从L-HC到视锥细胞的反馈连接的运作机制。
