Roger, please indicate which of the mechanisms is ING and which is PING.
Also, it would be helpful to have a color picture illustrating each mechanism.
I suggest mentioning also the waves of gamma activity which have been described in primary visual cortex [Gabriel, A. & Eckhorn, R. A multi-channel correlation method detects traveling gamma-waves in monkey visual cortex. J Neurosci Methods 131, 171-84 (2003).] The phase continuity of such gamma-waves was proposed to be a basis of spatial feature binding across entire objects [Eckhorn, R., Gail, A., Bruns, A., Gabriel, A., Al-Shaikhli, B. & Saam, M. Neural mechanisms of visual associative processing. Acta Neurobiol Exp (Wars) 64, 239-52 (2004).]
The point about 2-site stimulation producing gamma to beta "switch" is not very clear. Has the stimulation to be applied after gamma is initiated and that triggers switch to beta? Or such stimulation first triggers gamma activity which later switches to beta? Also, what kind of synaptic plasticity is involved?