The role of feedback in shaping the extra-classical receptive field of cortical neurons: A recurrent network model
The role of feedback in shaping the extra-classical receptive field of cortical neurons: A recurrent network model
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DOI：
10.1523/jneurosci.1253-06.2006
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发表时间：
2006-09-06
影响因子：
5.3
通讯作者：
Bressloff, Paul C.
中科院分区：
文献类型：
--
作者：
Schwabe, Lars;Obermayer, Klaus;Bressloff, Paul C.
感觉皮层神经元的反应受到嵌入刺激的空间背景的影响。在初级视觉皮质(V1)，对感受野(RF)中心刺激的方位选择性反应被RF周围相似方向的刺激抑制。环绕抑制是知觉图形-背景分离的一种可能的神经关联，传统上被认为是通过长距离水平连接在V1内产生的。然而，最近已经表明，这些连接太短且太慢，不能调节来自RF环绕的远处区域的快速抑制。我们使用一个解剖学和生理学上受限的猕猴V1递归网络模型，来展示比水平连接更快、更远范围的区域间反馈连接如何产生“远”环绕抑制。我们提供了一个新的解决之谜，即如何通过兴奋性反馈轴突接触V1中的主要兴奋性神经元来产生环绕抑制。其基本机制包括从远端周围的发散反馈连接靶向锥体神经元，将单突触水平连接发送到RF中心的兴奋性和抑制性神经元。我们模型的几个预测之一是“抑制性远环绕”并不总是抑制性的，但可以促进RF中心的反应，这取决于对局部抑制剂的兴奋性驱动力的大小。我们的模型提供了一个自顶向下反馈信号如何直接对简单感觉刺激产生皮质神经元反应的一般机制。
The responses of neurons in sensory cortices are affected by the spatial context within which stimuli are embedded. In the primary visual cortex (V1), orientation-selective responses to stimuli in the receptive field (RF) center are suppressed by similarly oriented stimuli in the RF surround. Surround suppression, a likely neural correlate of perceptual figure-ground segregation, is traditionally thought to be generated within V1 by long-range horizontal connections. Recently however, it has been shown that these connections are too short and too slow to mediate fast suppression from distant regions of the RF surround. We use an anatomically and physiologically constrained recurrent network model of macaque V1 to show how interareal feedback connections, which are faster and longer-range than horizontal connections, can generate "far" surround suppression. We provide a novel solution to the puzzle of how surround suppression can arise from excitatory feedback axons contacting predominantly excitatory neurons in V1. The basic mechanism involves divergent feedback connections from the far surround targeting pyramidal neurons sending monosynaptic horizontal connections to excitatory and inhibitory neurons in the RF center. One of several predictions of our model is that the "suppressive far surround" is not always suppressive, but can facilitate the response of the RF center, depending on the amount of excitatory drive to the local inhibitors. Our model provides a general mechanism of how top-down feedback signals directly contribute to generating cortical neuron responses to simple sensory stimuli.