The second condition is the compatibility of SMO frequencies across and within structures. While the hippocampal LFP is dominated by coherent theta and gamma oscillations, the hippocampal pyramidal cells express mainly theta frequency SMOs. If phase coding in the hippocampus relies on theta, it is not clear what role gamma oscillations may play. Likewise, entorhinal cortical neurons express theta frequency SMOs. In contrast, sensory organs and primary sensory areas are dominated by gamma oscillations. Notably, we observed visual feature-dependent spike phase modulation relative to the gamma band LFP and not to alpha, while other studies reported phase modulation relative to alpha band LFP (Belitski et al., 2008).