Small modulation of ongoing cortical dynamics by sensory input during natural vision
Small modulation of ongoing cortical dynamics by sensory input during natural vision
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DOI：
10.1038/nature02907
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发表时间：
2004-09-30
期刊：
影响因子：
64.8
通讯作者：
Weliky, M
中科院分区：
文献类型：
--
作者：
Fiser, J;Chiu, CY;Weliky, M
在视觉过程中，人们认为初级视觉皮层的神经活动主要由来自环境的感觉输入驱动。然而，视觉皮层神经元对重复出现的相同刺激的反应具有高度的可变性(1-4)。尽管由于皮层内的随机自发活动，这种变异性被认为是噪音(5-7)，但最近的研究表明，自发活动具有高度连贯的时空结构(8-13)。这提出了一种可能性，即这种自发活动的模式可能会在自然观看条件下影响神经反应，其程度比之前想象的更大。在这里，我们研究了雪貂从睁眼到成熟期间，在清醒、自由观看的情况下，自发活动与初级视觉皮层神经元对动态自然场景和随机噪声电影图像的反应之间的关系。在年轻动物中，诱发的神经活动与输入信号结构之间的对应关系较弱，但随着年龄的增长而系统地改善。这种改善与自发活动动态的转变有关。在包括成熟动物在内的所有年龄段，自发神经放电的相关性仅因视觉刺激而略有改变，而与感觉输入无关。这些结果表明，在发育中和成熟的视觉皮层中，感觉诱发的神经活动代表输入信号对正在进行的电路动态的调制和触发，而不是直接反映输入信号本身的结构。
During vision, it is believed that neural activity in the primary visual cortex is predominantly driven by sensory input from the environment. However, visual cortical neurons respond to repeated presentations of the same stimulus with a high degree of variability(1-4). Although this variability has been considered to be noise owing to random spontaneous activity within the cortex(5-7), recent studies show that spontaneous activity has a highly coherent spatio-temporal structure(8-13). This raises the possibility that the pattern of this spontaneous activity may shape neural responses during natural viewing conditions to a larger extent than previously thought. Here, we examine the relationship between spontaneous activity and the response of primary visual cortical neurons to dynamic natural-scene and random-noise film images in awake, freely viewing ferrets from the time of eye opening to maturity. The correspondence between evoked neural activity and the structure of the input signal was weak in young animals, but systematically improved with age. This improvement was linked to a shift in the dynamics of spontaneous activity. At all ages including the mature animal, correlations in spontaneous neural firing were only slightly modified by visual stimulation, irrespective of the sensory input. These results suggest that in both the developing and mature visual cortex, sensory evoked neural activity represents the modulation and triggering of ongoing circuit dynamics by input signals, rather than directly reflecting the structure of the input signal itself.