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Weak sensory stimuli can fully escape conscious perception and yet evoke minute electroencephalography (EEG) responses (1), indicating at least partial cortical processing of such “subliminal” input. We used functional magnetic resonance imaging (fMRI) during imperceptible electrical finger stimulation to characterize the extent and nature of associated cortical processing (2). No fMRI activation could be identified; ie, subliminal stimuli did not elicit any significant positive blood-oxygenation-level–dependent (BOLD) signal change. In contrast, statistical parametric maps for negative T contrasts (Fig. 1A) revealed distinct BOLD signal decreases, sharply localized at the hand area of the contralateral primary somatosensory cortex (S1), in the secondary somatosensory cortex (S2), and in the supplementary motor area (SMA). As either imperceptible stimuli or no stimuli at all were presented and, consequently, subjects …