RT Journal Article SR Electronic T1 Origin and modulation of the narrowband gamma oscillation in the mouse visual system JF bioRxiv FD Cold Spring Harbor Laboratory SP 050245 DO 10.1101/050245 A1 Aman B Saleem A1 Anthony D Lien A1 Michael Krumin A1 Bilal Haider A1 Miroslav Román Rosón A1 Asli Ayaz A1 Kimberly Reinhold A1 Laura Busse A1 Matteo Carandini A1 Kenneth D Harris YR 2016 UL http://biorxiv.org/content/early/2016/04/28/050245.abstract AB Visual cortex (V1) exhibits two types of gamma oscillation: a well-characterized broadband (30-90Hz) rhythm, and a narrowband oscillation occurring at frequencies close to 60 Hz in mice. We investigated the source of narrowband gamma, the factors modulating its strength, and its relationship to broadband gamma. Narrowband and broadband gamma power were uncorrelated. Increasing visual contrast had opposite effects on the two kinds of gamma activity: it increased broadband power, but suppressed the narrowband oscillation. Narrowband power was strongest in layer 4, and was mediated primarily by excitatory currents entrained by rhythmically firing neuronal ensembles in the lateral geniculate nucleus (LGN). Silencing the cortex optogenetically did not affect narrowband rhythmicity in either LGN spike trains or cortical EPSCs, suggesting that this oscillation reflects unidirectional flow of information from LGN to V1.HighlightsLocal field potential in mouse primary visual cortex exhibits a pronounced narrowband gamma oscillation close to 60 Hz.Unlike broadband gamma, narrowband gamma is present in excitatory synaptic inputs to individual V1 neurons, and suppressed by visual contrastNarrowband gamma is highest in the thalamorecipient layer 4Lateral geniculate nucleus neurons fire synchronously at the narrowband gamma frequency, independent of V1 activity.