Binding of cortical functional modules by synchronous high frequency oscillations.

High-frequency phase-locked oscillations have been hypothesized to facilitate integration ('binding') of information encoded across widespread cortical areas. Ripples (~100ms long ~90Hz oscillations) co-occur ('co-ripple') broadly in multiple states and locations, but have only been associated with memory replay. We tested whether cortico-cortical co-ripples subserve a general role in binding by recording intracranial EEG during reading. Co-rippling increased to words versus consonant-strings between visual, wordform and semantic cortical areas when letters are binding into words, and words to meaning. Similarly, co-ripples strongly increased before correct responses between executive, response, wordform and semantic areas when word meanings bind instructions and response. Task-selective co-rippling dissociated from non-oscillatory activation and memory reinstatement. Co-ripples were phase-locked at zero-lag, even at long distances (>12cm), supporting a general role in cognitive binding.