Unaware processing of tools in the neural system for object-directed action representation

The hypothesis that the brain constitutively encodes observed manipulable objects for the actions they afford is still debated. Yet, crucialevidence demonstrating that, even in the absence of perceptual awareness, the mere visual appearance of a manipulable object triggers avisuomotor coding in the action representation system including the premotor cortex, has hitherto not been provided. In this fMRI study,we instantiated reliable unaware visual perception conditions by means of continuous flash suppression, and we tested in 24 healthyhuman participants (13 females) whether the visuomotor object-directed action representation system that includes left-hemisphericpremotor, parietal, and posterior temporal cortices is activated even under subliminal perceptual conditions. We found consistentactivation in the target visuomotor cortices, both with and without perceptual awareness, specifically for pictures of manipulable versusnon-manipulable objects. By means of a multivariate searchlight analysis, we also found that the brain activation patterns in thisvisuomotor network enabled the decoding of manipulable versus non-manipulable object picture processing, both with and withoutawareness. These findings demonstrate the intimate neural coupling between visual perception and motor representation that underliesmanipulable object processing: manipulable object stimuli specifically engage the visuomotor object-directed action representationsystem, in a constitutive manner that is independent from perceptual awareness. This perceptuo-motor coupling endows the brain withan efficient mechanism for monitoring and planning reactions to external stimuli in the absence of awareness.