Saleem Aman B, Lien Anthony D, Krumin Michael, Haider Bilal, Rosón Miroslav Román, Ayaz Asli, Reinhold Kimberly, Busse Laura, Carandini Matteo, Harris Kenneth D
UCL Institute of Ophthalmology, University College London, London WC1E 6BT, UK; UCL Institute of Neurology, University College London, London WC1E 6BT, UK; Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK.
Division of Biological Sciences, University of San Diego, San Diego, CA 92110, USA.
Neuron. 2017 Jan 18;93(2):315-322. doi: 10.1016/j.neuron.2016.12.028.
Primary visual cortex exhibits two types of gamma rhythm: broadband activity in the 30-90 Hz range and a narrowband oscillation seen in mice at frequencies close to 60 Hz. We investigated the sources of the narrowband gamma oscillation, the factors modulating its strength, and its relationship to broadband gamma activity. Narrowband and broadband gamma power were uncorrelated. Increasing visual contrast had opposite effects on the two rhythms: it increased broadband activity, but suppressed the narrowband oscillation. The narrowband oscillation was strongest in layer 4 and was mediated primarily by excitatory currents entrained by the synchronous, rhythmic firing of neurons in the lateral geniculate nucleus (LGN). The power and peak frequency of the narrowband gamma oscillation increased with light intensity. Silencing the cortex optogenetically did not abolish the narrowband oscillation in either LGN firing or cortical excitatory currents, suggesting that this oscillation reflects unidirectional flow of signals from thalamus to cortex.
30-90赫兹范围内的宽带活动以及在小鼠中接近60赫兹频率处出现的窄带振荡。我们研究了窄带伽马振荡的来源、调节其强度的因素及其与宽带伽马活动的关系。窄带和宽带伽马功率不相关。增加视觉对比度对这两种节律有相反的影响：它增加了宽带活动，但抑制了窄带振荡。窄带振荡在第4层最强，主要由外侧膝状体核（LGN）中神经元同步、节律性放电所夹带的兴奋性电流介导。窄带伽马振荡的功率和峰值频率随光强度增加。通过光遗传学方法使皮层沉默并没有消除LGN放电或皮层兴奋性电流中的窄带振荡，这表明这种振荡反映了从丘脑到皮层的单向信号流动。
