Spontaneous and sensory-driven gamma oscillations engage distinct cortical circuitry.

16 Gamma oscillations are a robust component of sensory responses but are also part of the 17 background spontaneous activity of the brain. To determine whether the properties of gamma 18 oscillations in cortex are specific to their mechanism of generation, we compared in mouse 19 visual cortex in vivo, the laminar geometry and single neuron rhythmicity of oscillations 20 produced during sensory representation with those occurring spontaneously in the absence of 21 stimulation. In mouse visual cortex under anesthesia (isoflurane and xylazine), visual stimulation 22 triggered oscillations mainly between 20-50 Hz, which, because of their similar functional 23 significance to gamma oscillations in higher mammals, we define here as gamma range. Sensory 24 representation in visual cortex specifically increased gamma oscillation amplitude in the 25 supragranular (L2/3) and granular (L4) layers, and strongly …