Miyawaki Experiment

Perceptual experience consists of an enormous number of possible states. Previous fMRI studies have predicted a perceptual state by classifying brain activity into prespecified categories. Constraint-free visual image reconstruction is more challenging, as it is impractical to specify brain activity for all possible images.
Miyawaki experiment
In this study, we reconstructed visual images by combining local image bases of multiple scales, whose contrasts were independently decoded from fMRI activity by automatically selecting relevant voxels and exploiting their correlated patterns. Binary contrast, 10*10 patch images (2100 possible states) were accurately reconstructed without any image prior on a single trial or volume basis by measuring brain activity only for several hundred random images. Reconstruction was also used to identify the presented image among millions of candidates. The results suggest that our approach provides an effective means to read out complex perceptual states from brain activity while discovering information representation in multivoxel patterns.
Miyawaki experiment
In the present study, we attempted to reconstruct visual images defined by binary contrast patterns consisting of 10*10 square patches. We used local image bases of four scales: 1*1, 1*2, 2*1, and 2*2 patch areas. They were placed at every location in the image with overlaps. Although image elements larger than 2*2 or those with nonrectangular shapes could be used, the addition of such elements did not improve the reconstruction performance. fMRI signals were measured while subjects viewed a sequence of visual images consisting of binary contrast patches on a 10*10 grid. In the ‘‘random image session,’’ a random pattern was presented for 6s followed by a 6s rest period. A total of 440 different random images were shown (each presented once).



OUTPUT

OUTPUT

OUTPUT

OUTPUT

OUTPUT

OUTPUT