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Abstract:
Spontaneous spiral cortical waves have been reported to exist in rodents under specific pharmacological manipulations as well as during induced sleep-like states (Huang et al.,2010). The role of this highly organized mesoscopic phenomenon as well as the underlying mechanism are currently elusive. Neither the emergence of these patterns nor the relationship of the spatio-temporal dynamics of the waves to the underlying cortical functional architecture are understood or even examined in detail.
Here, we used voltage sensitive dye imaging to record the dynamics of ongoing sub-threshold potentials in the anesthetized primate. Spatial phase maps at each point in time revealed, also in these experiments, the existence of spontaneously emerging spiral waves. We found that spiral waves emerged from cortical space-time dependent activity within the Theta frequency band (4-8Hz). In particular, phase singularities emerged in oscillating bursts blow 1Hz, which fits the well-known slow waves, that is, the thalamus-driven up- and down-state alternations. The spatio-temporal dynamics of the spiral waves, as well as the phase singularities were found to be constrained by the underlining functional architecture of the primate primary visual cortex. These results suggest that spiral waves are an important cortical phenomenon, in the sense that, they can shed light on some basic principles underlying cortical microcircuit dynamics at the mesoscopic level.
