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. 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 x 10-patch images (2(100) 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.

Eye contact provides a communicative link between humans, prompting joint attention. As spontaneous brain activity might have an important role in the coordination of neuronal processing within the brain, their inter-subject synchronization might occur during eye contact. To test this, we conducted simultaneous functional MRI in pairs of adults. Eye contact was maintained at baseline while the subjects engaged in real-time gaze exchange in a joint attention task. Averted gaze activated the bilateral occipital pole extending to the right posterior superior temporal sulcus, the dorso-medial prefrontal cortex, and the bilateral inferior frontal gyrus. Following a partner's gaze toward an object activated the left intraparietal sulcus. After all the task-related effects were modeled out, inter-individual correlation analysis of residual time-courses was performed. Paired subjects showed more prominent correlations than non-paired subjects in the right inferior frontal gyrus, suggesting that this region is involved in sharing intention during eye contact that provides the context for joint attention.

It remains unknown why we generate spontaneous eyeblinks every few seconds, more often than necessary for ocular lubrication. Because eyeblinks tend to occur at implicit breakpoints while viewing videos, we hypothesized that eyeblinks are actively involved in the release of attention. We show that while viewing videos, cortical activity momentarily decreases in the dorsal attention network after blink onset but increases in the default-mode network implicated in internal processing. In contrast, physical blackouts of the video do not elicit such reciprocal changes in brain networks. The results suggest that eyeblinks are actively involved in the process of attentional disengagement during a cognitive behavior by momentarily activating the default-mode network while deactivating the dorsal attention network.functional MRI | natural vision W e spontaneously generate an eyeblink every few seconds-15-20 per minute, on average. These spontaneous eyeblinks are believed to occur to lubricate the cornea, but the rate is several times more than required for ocular lubrication (1, 2). Therefore, it remains an open question why eyeblinks are generated so frequently at the cost of blocking visual input for a period amounting to 10% of our waking hours (3).Spontaneous eyeblinks tend to occur at breakpoints of attention, such as the end of a sentence while reading (4), a pause by the speaker while listening to a speech (5), and implicit breakpoints while viewing videos (3). That eyeblinks occur not only at explicit but also at implicit breakpoints raises the possibility that spontaneous eyeblinks play an active role in the release of attention from external stimuli while attentively engaging in a cognitive task. Clinical neurological studies support this possibility. People who had a difficulty of voluntary eye movements often generate eyeblinks to terminate the spasms of visual fixations (6-8).Assuming the role of the eyeblink in disengaging attention, each spontaneous eyeblink should be associated with inhibition of the dorsal attentional network that mediates the allocation of attention (9), and with an activation of the default-mode network (DMN), which is known to counteract the dorsal attention network (10) and is implicated in introspection (11, 12). We hypothesized that spontaneous eyeblinks control the disengagement of attention by momentarily deactivating the dorsal attention network while activating the DMN.To test this hypothesis, we used fMRI to examine the cortical activity of 10 healthy participants (mean age: 21.7 y) in relation to the onset of each spontaneous eyeblink while the participants attentively viewed video clips from "Mr. Bean," a British television comedy. The story was chosen because our previous behavioral study demonstrated that the timing of spontaneous eyeblinks was synchronized across participants at the implicit breakpoints of the same video (3). ResultsThe participants spontaneously generated an average of 17.4 eyeblinks per minute (ranging from 3.1-51.0) while viewing the videos. Event-rel...

Our brains represent the position of a visual stimulus egocentrically, in either retinal or craniotopic coordinates. In addition, recent behavioral studies have shown that the stimulus position is automatically represented allocentrically relative to a large frame in the background. Here, we investigated neural correlates of the 'background coordinate' using an fMRI adaptation technique. A red dot was presented at different locations on a screen, in combination with a rectangular frame that was also presented at different locations, while the participants looked at a fixation cross. When the red dot was presented repeatedly at the same location relative to the rectangular frame, the fMRI signals significantly decreased in the right precuneus. No adaptation was observed after repeated presentations relative to a small, but salient, landmark. These results suggest that the background coordinate is implemented in the right precuneus.