Abstract
Multivoxel pattern analysis (MVPA) has become a standard tool for decoding mental states from brain activity patterns. Recent studies have demonstrated that MVPA can be applied to decode activity patterns of a certain region from those of the other regions. By applying a similar region-to-region decoding technique, we examined whether the information represented in the visual areas can be explained by those represented in the other visual areas. We first predicted the brain activity patterns of an area on the visual pathway from the others, then subtracted the predicted patterns from their originals. Subsequently, the visual features were derived from these residuals. During the visual perception task, the elimination of the top-down signals enhanced the simple visual features represented in the early visual cortices. By contrast, the elimination of the bottom-up signals enhanced the complex visual features represented in the higher visual cortices. The directions of such modulation effects varied across visual perception/imagery tasks, indicating that the information flow across the visual cortices is dynamically altered, reflecting the contents of visual processing. These results demonstrated that the distillation approach is a useful tool to estimate the hidden content of information conveyed across brain regions.
Highlights
IntroductionDecoding gives meaning to the activity patterns inside the brain, providing a potential for reverse engineering in order to understand how the brain organizes and stores information
Brain decoding has drawn interest from neuroscientists for decades
We calculated the functional connectivity between region of interest (ROI) associated with the visual processing
Summary
Decoding gives meaning to the activity patterns inside the brain, providing a potential for reverse engineering in order to understand how the brain organizes and stores information. A recent study (Horikawa and Kamitani, 2017) presented a decoding approach for generic decoding of visual features in both perception and imagery tasks. The authors suggested that the mental imagery is a Distillation of Regional Activity type of top-down processing, whereas mental perception is a bottom-up process. Interplay between top-down and bottomup processing helps sharpen the neural representation of stimuli (Abdelhack and Kamitani, 2018). To unveil the “true pattern” reflecting the received visual stimuli, one should eliminate the influence of top-down signals
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