Conscious experience is one of the most difficult and thorny problems in psychological science. Its study has been neglected for many years, either because it was thought to be too difficult, or because the relevant evidence was thought to be poor. Bernard Baars suggests a way to specify empirical constraints on a theory of consciousness by contrasting well-established conscious phenomena - such as stimulus representations known to be attended, perceptual, and informative - with closely comparable unconscious ones - such as (...) stimulus representations known to be preperceptual, unattended, or habituated. Adducing data to show that consciousness is associated with a kind of global workplace in the nervous system, and that several brain structures are known to behave in accordance with his theory, Baars helps to clarify many difficult problems. (shrink)

A general conceptual framework for large-scale neocortical dynamics based on data from many laboratories is applied to a variety of experimental designs, spatial scales, and brain states. Partly distinct, but interacting local processes (e.g., neural networks) arise from functional segregation. Global processes arise from functional integration and can facilitate (top down) synchronous activity in remote cell groups that function simultaneously at several different spatial scales. Simultaneous local processes may help drive (bottom up) macroscopic global dynamics observed with electroencephalography (EEG) or (...) magnetoencephalography (MEG). A local/global dynamic theory that is consistent with EEG data and the proposed conceptual framework is outlined. This theory is neutral about properties of neural networks embedded in macroscopic fields, but its global component makes several qualitative and semiquantitative predictions about EEG measures of traveling and standing wave phenomena. A more general “metatheory” suggests what large-scale quantitative theories of neocortical dynamics may be like when more accurate treatment of local and nonlinear effects is achieved. The theory describes the dynamics of excitatory and inhibitory synaptic action fields. EEG and MEG provide large-scale estimates of modulation of these synaptic fields around background levels. Brain states are determined by neuromodulatory control parameters. Purely local states are dominated by local feedback gains and rise and decay times of postsynaptic potentials. Dominant local frequencies vary with brain region. Other states are purely global, with moderate to high coherence over large distances. Multiple global mode frequencies arise from a combination of delays in corticocortical axons and neocortical boundary conditions. Global frequencies are identical in all cortical regions, but most states involve dynamic interactions between local networks and the global system. EEG frequencies may involve a “matching” of local resonant frequencies with one or more of the many, closely spaced global frequencies. Key Words: binding problem; cell assemblies; coherence; EEG; limit cycles; neocortical dynamics; pacemakers; phase locking; spatial scale; standing waves; synchronization. Footnotes1 The relationship between the synaptic action fields proposed in the target article and cell assemblies is clarified with Figure R1 (p. 416) of the Response. (This figure was not available to Commentators. (shrink)

According to behavioural theories deriving from pragmatism, gestalt psychology, existentialism, and ecopsychology, knowledge about the world is gained by intentional action followed by learning. In terms of the neurodynamics described here, if the intending of an act comes to awareness through reafference, it is perceived as a cause. If the consequences of an act come to awareness through proprioception and exteroception, they are perceived as an effect. A sequence of such states of awareness comprises consciousness, which can grow in complexity (...) to include self-awareness. Intentional acts do not require awareness, whereas voluntary acts require self-awareness. Awareness of the action/perception cycle provides the cognitive metaphor of linear causality as an agency. Humans apply this metaphor to objects and events in the world to predict and control them, and to assign social responsibility. Thus, linear causality is the bedrock of technology and social contracts. Complex material systems with distributed non-linear feedback, such as brains and their neural and behavioural activities, cannot be explained by linear causality. They can be said to operate by circular causality without agency. The nature of self-control is described by breaking the circle into a forward limb, the intentional self, and a feedback limb, awareness of the self and its actions. The two limbs are realized through hierarchically stratified kinds of neural activity. Intentional acts are produced by the self-organized microscopic neural activity of cortical and subcortical components in the brain. Awareness supervenes as a macroscopic ordering state, that defers action until the self-organizing microscopic process has reached closure in reflective prediction. Agency, which is removed from the causal hierarchy by the appeal to circularity, re-appears as a metaphor by which events in the world are anthropomorphized, making them appear subject to human control. (shrink)