Communication between Brain Areas Based on Nested Oscillations

The new framework. The synchronization in the alpha-band establishes the functional connection between A and C. This allows for representational specific neuronal firing reflected by the gamma band activity to flow to region C. The blocking of communication between B and C is achieved by high alpha power in B and an asynchrony between B and C. Therefore both modulations in alpha-band power, as in gating by inhibition, and phase synchronization between the regions, as in CTC, are determining the routing of information between regions. Note that phase synchronization is assumed in the alpha band and the information transfer is reflect by gamma-band activity.

Exchange of phase coded information. a, Two stimuli processed by two pools of neurons A and B, e.g., in V1. The pools both project to a pool of neurons C downstream in the hierarchy, e.g., in V4. Because of this bottleneck in the visual system, it is important that neurons coding for A and B in V1 are not activated simultaneously. For the information related to the two stimuli to be transferred from V1 to V4, we propose two mechanisms. b, A single alpha generator in V1 controls for the timing of activation of neurons in pool A and B as reflected in the gamma band. The activation of the most excitable neurons, i.e., cells in pool A, overcomes the pulse of inhibition early in the alpha cycle followed by neurons in pool B (see Jensen et al. 2014 for details). The temporal organization is then transmitted to the pool of neurons in C. c, Another possibility is that the magnitude of the alpha oscillations is modulated locally and is lower for one of the representations compared with the other. Because the alpha inhibition is lower for A, the respective neurons fire earlier than B. This temporal organization is then transmitted to C.