Fig. 2.

Coherent response-pattern fluctuations in natural image data. A) The response amplitudes for 5 natural images are shown for a subset of voxels in visual areas V1 and V2 of subject S1. The responses in all voxels in both V1 and V2 were low for the first stimulus, stronger for the second stimulus and again lower for the fourth stimulus. That is, the visual areas showed coherent dynamics in their response patterns. B) The mean and variance of the response pattern amplitudes for 70 natural stimuli are shown for visual areas V1 and V2. Both showed highly coherent dynamics between the visual areas. C) The matrices show the mean correlations between response-pattern-means (top row) and variances (bottom row) between all pair-wise comparisons of the visual areas. The matrices are also visualized using multidimensional-scaling arrangement. What emerged from the coherence of the response-pattern fluctuations is the hierarchy of visual areas. D–F) When the comparisons were done between repeated presentations of the same stimuli (separate trials), the correlations in the response-pattern-mean and variance were much lower. As shown with the simulations in Fig. 1, this suggests a significant contribution of the coherent response fluctuations on the similarity of the RDMs from different visual areas in this data.