Subcortical Source and Modulation of the Narrowband Gamma Oscillation in Mouse Visual Cortex

• Published in: Neuron (Cambridge, Mass.) Mass.), 2017-01, Vol.93 (2), p.315-322
• Main Authors: Saleem, Aman B., Lien, Anthony D., Krumin, Michael, Haider, Bilal, Rosón, Miroslav Román, Ayaz, Asli, Reinhold, Kimberly, Busse, Laura, Carandini, Matteo, Harris, Kenneth D.
• Format: Article
• Language: English
• Subjects: Animals; Charitable foundations; Excitatory Postsynaptic Potentials - physiology; Experiments; gamma; Gamma Rhythm - physiology; Geniculate Bodies - physiology; Hypotheses; Inhibitory Postsynaptic Potentials - physiology; lateral geniculate nucleus; Mice; mouse vision; neural circuits; Neurons - physiology; Neurosciences; Photic Stimulation; primary visual cortex; Rhythm; Synapses - physiology; thalamus; Visual Cortex - physiology; Visual Pathways - physiology
• ISSN: 0896-6273; 1097-4199
• 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. •Mouse V1 exhibits a pronounced narrowband gamma oscillation close to 60 Hz•This oscillation is strongest in layer 4 and specific to excitatory currents•It increases with arousal and light intensity and decreases with visual contrast•It is seen in lateral geniculate neurons, regardless of V1 activity Saleem et al. discover that the narrowband gamma oscillation close to 60 Hz prevalent in the mouse visual cortex is inherited from the visual thalamus. The oscillation is enhanced by arousal and light intensity, and suppressed by visual contrast.