PT - JOURNAL ARTICLE AU - Jianguang Ni AU - Thomas Wunderle AU - Christopher M. Lewis AU - Robert Desimone AU - Ilka Diester AU - Pascal Fries TI - Gamma-rhythmic Gain Modulation AID - 10.1101/060582 DP - 2016 Jan 01 TA - bioRxiv PG - 060582 4099 - http://biorxiv.org/content/early/2016/06/24/060582.short 4100 - http://biorxiv.org/content/early/2016/06/24/060582.full AB - Cognition requires the dynamic modulation of effective connectivity, i.e. the modulation of the postsynaptic neuronal response to a given input. If postsynaptic neurons are rhythmically active, this might entail rhythmic gain modulation, such that inputs synchronized to phases of high gain benefit from enhanced effective connectivity. We show that visually induced gamma-band activity in awake macaque area V4 rhythmically modulates responses to unpredictable stimulus events. This modulation exceeded a simple additive superposition of a constant response onto ongoing gamma-rhythmic firing, demonstrating the modulation of multiplicative gain. Gamma phases leading to strongest neuronal responses also led to shortest behavioral reaction times, suggesting functional relevance of the effect. Furthermore, we find that constant optogenetic stimulation of anesthetized cat area 21a produces gamma-band activity entailing a similar gain modulation. As the gamma rhythm in area 21a did not spread backwards to area 17, this suggests that postsynaptic gamma is sufficient for gain modulation.