Late EEG responses are absent for conscious but task-irrelevant stimuli

Thousands of neural circuits are activated in our brains each second, but only some of them (quite mysteriously) give rise to conscious perception (Koch, 2004). The neuroscience of consciousness is the quest to identify these processes: a crucial pursuit with a wide range of applications, such as assessing consciousness in comatose patients and animals and restoring conscious sensory functions in brain-damaged patients. A first step toward solving the ambitious problem of explaining consciousness is recognizing the brain regions and the temporal dynamics of neural processes involved in generating conscious perceptions. For this problem, two conflicting views have been proposed. One theory, the global neuronal workspace (Dehaene and Naccache, 2001), suggests that consciousness arises with a global late ignition ( 300?500 ms) across different cortical regions (Dehaene and Changeux, 2011). Another view asserts that recurrent cortical activity at earlier latencies (150?250 ms) corresponds more closely to conscious perception (Lamme, 2000; Koivisto and Revonsuo, 2010).