Spatiotemporal organization of fast (>200 Hz) electrical oscillations in rat Vibrissa/Barrel cortex.

A 64-channel electrode array was used to study the spatial and temporal characteristics of fast (>200 Hz) electrical oscillations recorded from the surface of rat cortex in both awake and anesthetized animals. Transient vibrissal displacements were effective in evoking oscillatory responses in the vibrissa/barrel field and were tightly time-locked to stimulus onset, coinciding with the earliest temporal components of the coincident slow-wave response. Vibrissa-evoked fast oscillations exhibited modality specificity and were earliest and of largest amplitude over the cortical barrel, which corresponded to the vibrissa stimulated, spreading to sequentially engage neighboring barrels over subsequent oscillatory cycles. The response was enhanced after paired-vibrissal stimulation and was sensitive to time delays between movement of separate vibrissae. These data suggest that spatiotemporal interactions between fast oscillatory bursts in the barrel field may play a role in rapidly integrating information from the vibrissal array during the earliest cortical response to somatosensory stimulation.