ANALYSIS OF VISUAL MICROCIRCUITS

视觉微电路分析

• 批准号: 2164623
• 负责人: ETHAN D COHEN
• 金额: $ 13.31万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-07-01 至 1997-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2164623
• 关键词: amacrine cells; electrophysiology; evoked potentials; excitatory aminoacid; glutamate receptor; laboratory rabbit; motion perception; neural information processing; neural inhibition; retinal bipolar neuron; retinal ganglion; single cell analysis; visual fields; visual perception; visual stimulus

Direction selectivity is a complex receptive field property displayed by many neurons in the visual system. Each cell fires a series of action potentials to motion of a bar stimulus moved across the receptive field in a "preferred" direction. while movement of the bar in the opposite direction, termed the "null" direction evokes little or no response. The rabbit retina provides a rich source of direction selective ganglion cells, yet little is known about the synaptic input to these cells. Furthermore, the directional preferences of these cells are not obvious from their dendritic morphologies. I have found that certain types of excitatory amino acid (EAA) receptors appear to be critical to the function of the direction preferring mechanism of direction selective ganglion cells. In the presence of two excitatory amino acid receptor antagonists, NBQX and DNQX, the directional preference of these ganglion cells is lost to bar stimuli, and the ganglion cells respond equally to bar movement in both directions. Many theories on direction selectivity propose that a bar stimulus moving in the "null" direction of the receptive field activates a spatially asymmetric, feedforward. sustained inhibition. This preceding bar stimulus inhibition "shunts out" any bar excitation that follows it. Intracellular recordings in the rabbit retina reveal that the light evoked responses of many inner retinal neurons lose their sustained portions of the light evoked response in the presence of NBQX, and respond transiently to light. The hypothesis that the loss of direction selectivity in the "null" direction observed in NBQX is due to loss of a sustained feedforward inhibition will be tested by intracellular recording from neurons involved in direction selective pathways. Particular attention will be focused on the effects of NBQX and DNQX on the excitatory postsynaptic potentials of direction selective ganglion cells, and the starburst (cholinergic) amacrine cells thought to be presynaptic to these cells. The pharmacological nature of the excitatory amino acid synaptic input to direction selective ganglion cells will be characterized in retinal slices. These studies will provide new insights into the role of amacrine and bipolar cell function in the direction selective mechanism of these ganglion cells, and provide a more quantitative framework for improved models of direction selectivity in the visual system.

方向选择性是由 视觉系统中的许多神经元。每个细胞发射一系列动作 杆刺激运动的潜力在接受磁场上移动 一个“首选”方向。而杠铃在相对的移动 方向称为“无效”方向几乎没有响应。这 兔视网膜提供了丰富的方向选择性神经节 细胞对这些细胞的突触输入知之甚少。 此外，这些细胞的定向偏好并不明显 从它们的树突形态。我发现某些类型的 兴奋性氨基酸（EAA）受体似乎对 方向的功能优先选择方向选择性 神经节细胞。在两个兴奋性氨基酸受体的情况下 拮抗剂，NBQX和DNQX，这些神经节的定向偏好 细胞因杆刺激而丢失，而神经节细胞对 杆运动在两个方向上。关于方向选择性的许多理论 提出条刺激在 接受场会激活空间不对称的前馈。持续 抑制。这种先前的杆刺激抑制“分流”任何条 随之而来的激发。兔视网膜中的细胞内记录 揭示了许多内部视网膜神经元的诱发反应 它们在存在的情况下，它们的持续部分唤起了响应 NBQX，并对光线进行瞬时响应。损失的假设 在NBQX中观察到的“无效”方向上的方向选择性是由于 持续前进抑制的损失将通过细胞内测试 来自涉及方向选择途径的神经元的记录。 特别关注NBQX和DNQX对 方向选择性神经节的兴奋性突触后潜力 细胞和Starburst（胆碱能）的无长链细胞被认为是 这些细胞突触前。兴奋的药理性质 氨基酸突触输入到方向选择性神经节细胞将是 以视网膜切片为特征。这些研究将提供新的见解 纳入链氨酸和双极细胞在方向上的作用 这些神经节细胞的选择性机制，并提供更多 定量框架，以改善方向选择性模型 视觉系统。