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Gain modulation in visual cortex by noisy synaptic inputs.

机译：嘈杂的突触输入在视觉皮层中获得调制。

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摘要

Gain modulation of neuronal responses is widely observed in the cerebral cortex of both anesthetized and behaving animals. This dissertation examines mechanisms that may underlie different forms of gain modulation observed in visual cortex. We examine mechanisms that arise at many levels, beginning at the single-cell level (modulating the effective reversal potential of synaptic inputs to a cell) and ending at the network level (nonlinear interactions arising through recurrent connectivity).;In Chapter 2, we examine how the balance between excitation and inhibition in a neuron's input may affect how that neuron integrates its inputs. We have found that if excitatory and inhibitory inputs are balanced at a specific potential (we refer to this potential as the "balanced potential"), these do not alter the firing-rate responses, provided that they do not introduce additional noise. If these inputs do increase noise, their effect is close to input-gain modulation, an effect best described as scaling of the input. If the inputs are noisy but instead balanced at a more hyperpolarized potential, their effect is more like response-gain modulation, a divisive scaling of the neuron's firing rate.;In Chapter 3, we compare the effects of noisy synaptic inputs in a configuration that divisively scales firing-rate curves with the effects of subtractive mechanisms of inhibition and explore their possible role in producing multiplicative gain modulation effects observed in vivo, such as surround suppression and attention. The divisive mechanism of inhibition is more successful in producing both response-gain and inputgain modulation effects although the effects of subtractive inhibition can appear nonlinear.;Finally in Chapter 4, we examine how network effects can produce gain modulation phenomena. Specifically, we construct a recurrent network model of attention in visual cortex, and demonstrate how multiple forms of gain modulation can arise through nonlinear interactions that arise within a recurrent framework of connectivity. Gain modulation phenomena observed in vivo may arise from all or only a subset of the mechanisms examined in this study. As discussed in the final chapter, whole-cell recording techniques that measure in vivo conductance changes may allow distinguishing between these mechanisms.
机译：在麻醉动物和行为动物的大脑皮层中广泛观察到神经元反应的增益调节。本文探讨了可能在视觉皮层中观察到的不同形式的增益调制背后的机制。我们研究了从多个级别出现的机制，这些机制从单细胞级别开始（调制突触输入到细胞的有效逆转电位），并在网络级别结束（通过循环连接产生非线性相互作用）。检查神经元输入中的激励与抑制之间的平衡如何影响该神经元如何整合其输入。我们发现，如果兴奋性和抑制性输入在特定电位（我们将此电位称为“平衡电位”）上保持平衡，则只要不引入额外的噪音，它们就不会改变点火速率响应。如果这些输入确实增加了噪声，则它们的效果接近于输入增益调制，这种效果最好描述为输入的缩放比例。如果输入噪声很大，但在更高的超极化电位下保持平衡，则它们的效果更像是响应增益调制，这是神经元放电速率的分裂比例;在第3章中，我们比较了在配置中噪声突触输入的效果，即用抑制的消减机制分别对发射速率曲线进行标度，并探讨它们在产生体内观察到的倍增增益调制效应（如周围抑制和注意力）中的可能作用。尽管减法抑制的影响可能是非线性的，但抑制的分裂机制在产生响应增益和输入增益调制效果方面更为成功。最后，在第四章中，我们研究了网络效应如何产生增益调制现象。具体来说，我们构建了视觉皮层中关注的循环网络模型，并演示了如何通过连接的循环框架内发生的非线性相互作用来产生多种形式的增益调制。体内观察到的增益调节现象可能源于本研究中研究的全部或部分机制。如最后一章所讨论的，测量体内电导变化的全细胞记录技术可以区分这些机制。

著录项

  • 作者

    Ayaz, Asli.;

  • 作者单位

    University of California, Irvine.;

  • 授予单位 University of California, Irvine.;
  • 学科 Biology Neuroscience.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 165 p.
  • 总页数 165
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:38:25

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