Ripples (strong, short-lived oscillations in the local field potential associated with memory consolidation) have been previously reported in several brain areas including the hippocampus and neocortex. Compared to hippocampal ripples, relatively little is known about cortical ripples in terms of their spread and function. We inspected the ripple activity in the frequency range of 70-150 Hz in V1 and V4 of two macaque monkeys implanted with 16 Utah electrode arrays each [1]. The activity was recorded during resting state with occasional periods of drowsing. We observed prominent events with high ripple activity throughout the visual cortex that were separated by silent periods (>0.5 s). The ripple events were more prevalent during periods when the eyes were closed, with typically double the number of ripples per second compared to periods with the eyes open. During ripple events, we observed an increase in spiking activity and a large deflection of the local field potential that was slower than a typical hippocampal sharp wave. References: [1] Chen, X., Morales-Gregorio, A., Sprenger, J. et al. 1024-channel electrophysiological recordings in macaque V1 and V4 during resting state. Sci Data 9, 77 (2022). https://doi.org/10.1038/s41597-022-01180-1