The synaptic mechanism of direction selectivity in distal processes of starburst amacrine cells
The synaptic mechanism of direction selectivity in distal processes of starburst amacrine cells
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DOI：
10.1016/j.neuron.2006.08.007
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发表时间：
2006-09-21
期刊：
影响因子：
16.2
通讯作者：
Zhou, Z. Jimmy
中科院分区：
文献类型：
--
作者：
Lee, Seunghoon;Zhou, Z. Jimmy
膜片钳记录显示，在静止和移动光刺激期间，星爆无长突细胞（SAC）的远端过程主要接收来自感受野中心的兴奋性突触输入和来自周围的几乎纯粹的抑制性输入。直接周围抑制主要由相对的 SAC 之间的相互 GABA(A) 突触介导，在向心刺激运动过程中提供主导和延长的抑制。在表观运动刺激过程中同时进行的 Ca2+ 成像和电流钳记录进一步证明了离心激发和 GABA(A/C) 受体介导的向心抑制对 SAC 远端过程中方向选择性 Ca2+ 反应的贡献。因此，通过将 GABA 释放位点置于电紧张半隔离的远端过程中，并赋予这些位点相互的 GABAA 突触，SAC 使用径向对称的中心环绕感受野结构来构建极不对称电路。该电路可以整合至少三个级别的相互作用——中心激发、周围抑制和放大中心-周围拮抗作用的相互抑制——以在远端过程中产生稳健的方向选择性。
Patch-clamp recordings revealed that distal processes of starburst amacrine cells (SACs) received largely excitatory synaptic input from the receptive field center and nearly purely inhibitory inputs from the surround during both stationary and moving light stimulations. The direct surround inhibition was mediated mainly by reciprocal GABA(A) synapses between opposing SACs, which provided leading and prolonged inhibition during centripetal stimulus motion. Simultaneous Ca2+ imaging and current-clamp recording during apparent-motion stimulation further demonstrated the contributions of both centrifugal excitation and GABA(A/C)-receptor-mediated centripetal inhibition to the direction-selective Ca2+ responses in SAC distal processes. Thus, by placing GABA release sites in electrotonically semi-isolated distal processes and endowing these sites with reciprocal GABAA synapses, SACs use a radial-symmetric center-surround receptive field structure to build a polarasymmetric circuitry. This circuitry may integrate at least three levels of interactions-center excitation, surround inhibition, and reciprocal inhibitions that amplify the center-surround antagonism-to generate robust direction selectivity in the distal processes.