Neuroscience & Biobehavioral Reviews
December 17, 2011
Jaan Aru, Talis Bachmann, Wolf Singer et al.
612 citations
Identifying the neural correlates of consciousness (NCC) is a major goal in neuroscience, typically pursued by comparing brain activity when a person is conscious of a stimulus versus when they are not. This review argues that such contrastive analyses are problematic because they can capture not only the true NCC but also neural prerequisites for conscious processing and consequences that follow it. Previous findings may therefore be ambiguous. The authors propose experimental strategies to isolate the NCC from these confounds, aiming to refine the contrastive approach.
Consciousness and cognition
August 1, 2017
Jaan Aru, Talis Bachmann
42 citations
Conscious experience depends on attention and expectation, but some argue it can occur without attention. Experiments on iconic memory (IM) are often cited as evidence for attention-independent consciousness. A prior study found that when attention is diverted from an IM letter display, people fail to notice missing letters. This work replicates and extends that finding by measuring subjective visibility and testing post-cue effects. Results show that participants who do not realize letters are absent perceive illusory letters, indicating phenomenal consciousness persists even without attention. Expectation generates illusory content that overwrites valid IM content, suggesting this experimental paradigm cannot reliably assess iconic memory content.
Frontiers in neural circuits
January 1, 2018
William A Phillips, Talis Bachmann, Johan F Storm
General anesthetics may suppress either the level of consciousness (arousal) or its contents (specific percepts, thoughts, feelings). This distinction is important for understanding both anesthesia and the neural bases of consciousness. Evidence indicates that both level and content depend on apical input to neocortical pyramidal cells, which selectively amplifies relevant signals. What these cells transmit information about can be separated from arousal levels controlled by sub-cortical nuclei and from prioritization set by thalamocortical interactions. The authors hypothesize that when conscious, we have particular directly experienced mental states, and that anesthetics disrupt the subcellular processes that selectively amplify contextually relevant activities.
Consciousness and cognition
September 1, 2017
Renate Rutiku, Talis Bachmann
Electroencephalographic (EEG) potentials remain a valuable source of data and theories about the neural correlates of consciousness (NCC). This review organizes published work on EEG-based markers of NCC according to the time course of brain potentials relative to stimuli for which awareness is measured or manipulated. Brain potentials are treated as both dependent and independent variables. A notable pattern across studies is that relative negativization of event-related potentials (ERPs) tends to mark NCC.
Advances in Consciousness Research
June 17, 2015
Jaan Aru, Talis Bachmann, Wolf Singer et al.
Identifying the neural correlates of consciousness (NCC) is considered a key step toward understanding consciousness. Typical experiments contrast conditions with and without conscious perception, but this contrast captures not only neural activity directly tied to conscious experience but also prerequisites and consequences of that perception. To isolate the true neural basis of conscious experience, researchers must disentangle the NCC from these confounding processes. This review discusses recent experimental developments and proposes new empirical approaches to more precisely isolate the neural activity underlying conscious perception.