Dynamics of extraclassical surround modulation in three types of V1 neurons.
Dynamics of extraclassical surround modulation in three types of V1 neurons.
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DOI：
10.1152/jn.00692.2010
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发表时间：
2011-03
影响因子：
2.5
通讯作者：
Yong-Jun Liu;M. Hashemi‐Nezhad;D. C. Lyon
中科院分区：
文献类型：
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作者：
Yong-Jun Liu;M. Hashemi‐Nezhad;D. C. Lyon
经典感受野(CRF)外的视觉刺激可以影响初级视皮层(V1)神经元的反应。在CAT中记录单个单元的同时，我们在不同大小的圆孔中提出了漂移正弦光栅，以研究这种经典外环绕调制随时间的变化。在2-S刺激的整个过程中，发现了三种类型的神经元：1)68%的细胞是“抑制性”细胞，2)25%是“平台”细胞，呈现反应饱和而没有抑制，3)其余6%的细胞是“促进型”细胞。反应动力学分析表明，在反应开始时，一半的促进细胞、70%的平台细胞和所有抑制细胞的活动都受到周围环境的抑制。然而，在接下来的20-30ms内，环绕调制对抑制性细胞的抑制作用更强，对促进细胞的促进作用更强，对平台细胞的促进作用更弱。对于所有三种类型的细胞，这些调节效应在刺激开始后100到200毫秒之间稳定下来。因此，我们的发现说明了环绕调制的两个阶段。早期调节主要是抑制性的，与细胞类型无关，并且由于起病迅速，可能依赖于前馈机制。根据细胞类型的不同，较晚进化的环绕调制并不总是抑制的，并且可能通过不同的皮质回路组合而产生。对整个皮质柱调制的额外分析表明，促进细胞更大的兴奋场，主要存在于颗粒下层，可能有助于通过管内回路参与第二阶段的抑制。
Visual stimuli outside of the classical receptive field (CRF) can influence the response of neurons in primary visual cortex (V1). While recording single units in cat, we presented drifting sinusoidal gratings in circular apertures of different sizes to investigate this extraclassical surround modulation over time. For the full 2-s stimulus time course, three types of neurons were found: 1) 68% of the cells were "suppressive," 2) 25% were "plateau" cells that showed response saturation with no suppression, and 3) the remaining 6% of cells were "facilitative." Analysis of the response dynamics revealed that at response onset, activity of one-half of facilitative cells, 70% of plateau cells, and all suppressive cells is suppressed by the surround. However, over the next 20-30 ms, surround modulation changes to stronger suppression for suppressive cells, substantial facilitation for facilitative cells, and weak facilitation for plateau cells. For all three cell types, these modulatory effects then stabilize between 100 and 200 ms from stimulus onset. Thus our findings illustrate two stages of surround modulation. Early modulation is mainly suppressive regardless of cell type and, because of rapid onset, may rely on feedforward mechanisms. Surround modulation that evolves later in time is not always suppressive, depending on cell type, and may be generated through different combinations of cortical circuits. Additional analysis of modulation throughout the cortical column suggests the possibility that the larger excitatory fields of facilitative cells, primarily found in infragranular layers, may contribute to the second stage of suppression through intracolumnar circuitry.