Figure 1.

(A) An overview of the model. A ‘pyramidal interneuron gamma’ (PING) network composed of pyramidal excitatory (E) and inhibitory (I) neurons is modulated by an inhibitory drive in the alpha band (greek alpha) and stimulus input (S). (B) Schematic overview of the mechanism. The inhibitory alpha source (red) causes areas a–e to be activated sequentially depending on their input (a–c) or not at all when the input is too low (d, e) (C) The expected result from the simulations. Excitatory neurons with different input levels (a–c) fire in sequence (blue trace) according to the level of excitability, separated by bursts of inhibitory neuronal firing (grey trace) when the inhibitory alpha drive (red trace) is low. (D) Illustration showing how increasing alpha power decreases the duty cycle. The red line corresponds to the alpha inhibition that increases in power over time (from left to right). The blue trace corresponds to gamma activity generated by spiking neurons. The grey dashed line symbolized the threshold at which the inhibition is low enough for the most excited neurons to start firing. Parts of this figure have been reproduced with permission from Jensen et al. (2014).