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Decoding the visual and subjective contents of the human brain


The potential for human neuroimaging to read out the detailed contents of a person's mental state has yet to be fully explored. We investigated whether the perception of edge orientation, a fundamental visual feature, can be decoded from human brain activity measured with functional magnetic resonance imaging (fMRI). Using statistical algorithms to classify brain states, we found that ensemble fMRI signals in early visual areas could reliably predict on individual trials which of eight stimulus orientations the subject was seeing. Moreover, when subjects had to attend to one of two overlapping orthogonal gratings, feature-based attention strongly biased ensemble activity toward the attended orientation. These results demonstrate that fMRI activity patterns in early visual areas, including primary visual cortex (V1), contain detailed orientation information that can reliably predict subjective perception. Our approach provides a framework for the readout of fine-tuned representations in the human brain and their subjective contents.

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Figure 1: Orientation decoder and ensemble orientation selectivity.
Figure 2: Decoding stimulus orientation from ensemble fMRI activity in the visual cortex.
Figure 3: Orientation selectivity across the human visual pathway.
Figure 4: Pairwise decoding performance as a function of orientation difference (all pairs from eight orientations), for grating images (pixel intensities), fMRI images (voxel intensities) and transformed grating images.
Figure 5: Orientation preference map on flattened cortical surface.
Figure 6: Simulation of one-dimensional array of columns and voxels.
Figure 7: Mind-reading of attended orientation.


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We thank D. Remus and J. Kerlin for technical support, the Princeton Center for Brain, Mind and Behavior for MRI support and J. Haxby, D. Heeger and A. Seiffert for comments. This work was supported by grants from Japan Society for the Promotion of Science and National Institute of Information and Communications Technology to Y.K., and grants R01-EY14202 and P50-MH62196 from the US National Institutes of Health to F.T.

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Correspondence to Yukiyasu Kamitani.

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Supplementary information

Supplementary Fig. 1

Average fMRI responses to orientations for each visual area. (PDF 80 kb)

Supplementary Fig. 2

Average fMRI responses for voxels with the same orientation preference, shown by visual area. (PDF 50 kb)

Supplementary Fig. 3

Map of differential responses to eight orientations. (PDF 507 kb)

Supplementary Fig. 4

Split-display experiments. (PDF 273 kb)

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Kamitani, Y., Tong, F. Decoding the visual and subjective contents of the human brain. Nat Neurosci 8, 679–685 (2005).

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