Directional selective neurons in the awake LGN: response properties and modulation by brain state
Directional selective neurons in the awake LGN: response properties and modulation by brain state
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DOI：
10.1152/jn.00121.2014
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发表时间：
2014-07-01
影响因子：
2.5
通讯作者：
Swadlow, Harvey A.
中科院分区：
文献类型：
--
作者：
Hei, Xiaojuan;Stoelzel, Carl R.;Swadlow, Harvey A.
方向选择性神经元存在于兔和啮齿类动物的视网膜和外侧膝状体核中，在兔中，外侧膝状体核的方向选择性神经元投射到初级视皮层。在这里，我们比较LGN DS神经元的视觉反应特性与第4层的简单细胞，其中大多数表现出较强的方向/取向选择性。这些细胞群的差异很大，表明DS细胞对简单感受野的合成可能没有显著的贡献：（1）LGN DS细胞的一次谐波成分（F1）与平均放电频率（F0）的比值是强非线性的，而简单细胞的F1与平均放电频率（F0）的比值是强线性的; 2）LGN DS单元具有重叠的ON/OFF子场，而简单单元具有单个ON或OFF子场或两个空间分离的子场;以及3）LGNDS小区的优选方向与四个基本方向紧密相关，而简单小区的方向偏好分布更均匀。我们进一步表明，LGN DS神经元的方向选择性通过两种机制被警觉性强烈增强，1）对优选方向刺激的反应增加，2）对零方向刺激的反应抑制增强。最后，我们的模拟表明，这两个后果的警觉性可以分别服务，在一个基于矢量的人口代码，以加快刺激方向的计算时，兔子变得警觉。
Directionally selective (DS) neurons are found in the retina and lateral geniculate nucleus (LGN) of rabbits and rodents, and in rabbits, LGN DS cells project to primary visual cortex. Here, we compare visual response properties of LGN DS neurons with those of layer 4 simple cells, most of which show strong direction/orientation selectivity. These populations differed dramatically, suggesting that DS cells may not contribute significantly to the synthesis of simple receptive fields: 1) whereas the first harmonic component (F1)-to-mean firing rate (F0) ratios of LGN DS cells are strongly nonlinear, those of simple cells are strongly linear; 2) whereas LGN DS cells have overlapped ON/OFF subfields, simple cells have either a single ON or OFF subfield or two spatially separate subfields; and 3) whereas the preferred directions of LGN DS cells are closely tied to the four cardinal directions, the directional preferences of simple cells are more evenly distributed. We further show that directional selectivity in LGN DS neurons is strongly enhanced by alertness via two mechanisms, 1) an increase in responses to stimulation in the preferred direction, and 2) an enhanced suppression of responses to stimuli moving in the null direction. Finally, our simulations show that these two consequences of alertness could each serve, in a vector-based population code, to hasten the computation of stimulus direction when rabbits become alert.