Oscillatory Correlates of Visual Consciousness.

Conscious experiences are linked to brain activity, known as the neural correlates of consciousness (NCC). This review focuses on spontaneous brain oscillations—rhythmic fluctuations of neuronal activity characterized by frequency, amplitude, and phase. It surveys oscillatory measures that correlate with conscious perception and discusses techniques like entrainment for studying their causal role. Findings suggest that alpha-band activity (7-13 Hz) may index or causally support conscious perception. However, results highlight a challenge in NCC research: separating neural activity that is a prerequisite for consciousness from the substrate or consequences of conscious experience.

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Abstract

Conscious experiences are linked to activity in our brain: the neural correlates of consciousness (NCC). Empirical research on these NCCs covers a wide range of brain activity signals, measures, and methodologies. In this paper, we focus on spontaneous brain oscillations; rhythmic fluctuations of neuronal (population) activity which can be characterized by a range of parameters, such as frequency, amplitude (power), and phase. We provide an overview of oscillatory measures that appear to correlate with conscious perception. We also discuss how increasingly sophisticated techniques allow us to study the causal role of oscillatory activity in conscious perception (i.e., 'entrainment'). This review of oscillatory correlates of consciousness suggests that, for example, activity in the alpha-band (7-13 Hz) may index, or even causally support, conscious perception. But such results also showcase an increasingly acknowledged difficulty in NCC research; the challenge of separating neural activity necessary for conscious experience to arise (prerequisites) from neural activity underlying the conscious experience itself (substrates) or its results (consequences).