Exploring the role of expectations and stimulus relevance on stimulus-specific neural representations and conscious report.
Neuroscience of Consciousness January 1, 2019 Erik L Meijs, Pim Mostert, Heleen A. Slagter et al.
Expectations about an upcoming stimulus increase the likelihood of conscious report, but this enhancement does not occur by sharpening sensory neural representations. Using magnetoencephalography and an attentional blink paradigm, researchers decoded letter identity from neural activity. Early sensory representations were similar whether letters were reported or missed, and also when letter identity was task-irrelevant. Later sustained neural representations were uniquely present when letters were consciously reported, indicating a decision-dependent signal. Global pre-stimulus neural activity biased decisions toward 'seen' responses. No evidence supported the sharpening of sensory representations by top-down expectations.