Identifying multivariate patterns for illusory color perception using decoded fMRI neurofeedback

Abstract

Previous studies have shown that spontaneous fluctuations in prestimulus fMRI activity can predict trial-by-trial fluctuations in the perception of identical stimuli (Boly et al., 2007; Hesselmann et al., 2008, 2010; Sadaghiani et al., 2009; Rahnev et al., 2012; Pajani et al., 2015), yet such activity on its own does not seem to lead to conscious perception, even when awareness is carefully assessed in a forced-choice manner (Shibata et al., 2011; Amano et al., 2016). Here, we investigated why awareness is lacking in these cases, and whether it may be possible to make spontaneous activity conscious. We hypothesized that for consciousness to arise, specific neural patterns in both visual and frontoparietal areas may be required. To encourage the co-occurrence of such activity, we used MVPA-based decoded fMRI neurofeedback (DecNef) (Shibata et al., 2011). In previous work we identified frontoparietal voxel patterns representing high perceptual confidence (Cortese et al., 2016). Here, we rewarded subjects for simultaneously inducing these patterns for high perceptual confidence in frontoparietal areas and specific patterns for color in visual areas. We found that false color perception was associated with activation of high confidence patterns in frontoparietal areas, but not with activation of color patterns in visual areas. This suggests a unique role for a frontoparietal network in the promotion of spontaneous neural representations from an unconscious to a conscious state.