Siegel Markus, Donner Tobias H, Oostenveld Robert, Fries Pascal, Engel Andreas K
Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, University of Hamburg, 20246 Hamburg, Germany.
Cereb Cortex. 2007 Mar;17(3):732-41. doi: 10.1093/cercor/bhk025. Epub 2006 Apr 28.
A central goal in systems neuroscience is to understand how the brain encodes the intensity of sensory features. We used whole-head magnetoencephalography to investigate whether frequency-specific neuronal activity in the human visual cortex is systematically modulated by the intensity of an elementary sensory feature such as visual motion. Visual stimulation induced a tonic increase of neuronal activity at frequencies above 50 Hz. In order to define a functional frequency band of neuronal activity, we parametrically investigated which frequency band displays the strongest monotonic increase of responses with strength of visual motion. Consistently in all investigated subjects, this analysis resulted in a functional frequency band in the high gamma range from about 60 to 100 Hz in which activity reliably increased with visual motion strength. Using distributed source reconstruction, we found that this increase of high-frequency neuronal activity originates from several extrastriate cortical regions specialized in motion processing. We conclude that high-frequency activity in the human visual motion pathway may be relevant for encoding the intensity of visual motion signals.
系统神经科学的一个核心目标是了解大脑如何编码感觉特征的强度。我们使用全脑磁脑电图来研究人类视觉皮层中特定频率的神经元活动是否会被诸如视觉运动等基本感觉特征的强度系统地调节。视觉刺激在高于50赫兹的频率上诱导神经元活动的持续增加。为了定义神经元活动的功能频段，我们通过参数研究来确定哪个频段的反应随视觉运动强度的增加呈现出最强的单调增长。在所有被研究的受试者中，一致的是，该分析得出了一个约60至100赫兹的高伽马范围内的功能频段，其中活动随视觉运动强度可靠地增加。使用分布式源重建，我们发现高频神经元活动的这种增加源自几个专门用于运动处理的纹外皮层区域。我们得出结论，人类视觉运动通路中的高频活动可能与编码视觉运动信号的强度有关。
