A Field Theory of Consciousness

John, E. Roy

doi:10.1006/ccog.2001.0508

Cited by 186 publications

(96 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Whether the thalamus is pivotal to the sense of smell has important implications for neurobiological models of sensory perception. The thalamus is generally regarded as key for mediating conscious attention toward visual, auditory, somatosensory, and gustatory stimulation (John, 2001;Guillery and Sherman, 2002;Jones, 2006) and is critical for state-dependent gating of sensory information to higher-order neocortical regions (Stériade and Llinàs, 1988;McCormick and Bal, 1994;Jones, 2006). If the thalamus were shown not to be involved in odor perception, then this would help corroborate the idea that the functional neurobiology of the olfactory system is organized profoundly differently from other sensory systems (Murakami et al, 2005;Shepherd, 2005;Kay and Sherman, 2007).…”

Section: Introductionmentioning

confidence: 86%

Attention to Odor Modulates Thalamocortical Connectivity in the Human Brain

Plailly¹,

Howard²,

Gitelman³

et al. 2008

J. Neurosci.

195

153

View full text Add to dashboard Cite

It is widely assumed that the thalamus is functionally irrelevant for the sense of smell. Although animal studies suggest that the mediodorsal (MD) thalamus links primary olfactory (piriform) cortex to olfactory neocortical projection sites in orbitofrontal cortex (OFC), this transthalamic route is regarded to be inconsequential, particularly compared with a direct monosynaptic pathway linking piriform cortex and OFC. In this study, we combined functional magnetic resonance imaging with novel effective connectivity techniques to measure attention-dependent network coherence within direct (nonthalamic) and indirect (transthalamic) olfactory pathways. Human subjects were presented with (or without) an odor and with (or without) a tone, while selectively attending to either modality. Attention to odor significantly modulated neural coupling within the indirect pathway, strengthening MD thalamus-OFC connectivity. Critically, these effects were modality specific (odor Ͼ tone attention), directionally sensitive (forward Ͼ backward connections), and selective to route (indirect Ͼ direct pathway). Our findings support the idea that the human transthalamic pathway is an active modulatory target of olfactory attention. The results imply that olfaction, like all other sensory modalities, requires a thalamic relay, if only to consciously analyze a smell.

show abstract

Section: Introductionmentioning

confidence: 86%

Attention to Odor Modulates Thalamocortical Connectivity in the Human Brain

Plailly¹,

Howard²,

Gitelman³

et al. 2008

J. Neurosci.

195

153

View full text Add to dashboard Cite

show abstract

“…The chemical diversity of anesthetic compounds suggests that a diversity of brain structures are affected. Recent attempts with fMRI, PET, and quantitative EEG studies on anesthesia in human brains support this suspicion, and allow us to construct tentatively a minimal model of what structures are critically involved in anesthesia (Alkire et al, 2000;Cariani, 2000;John, 2001). Figure 1 illustrates schematically this minimal model, mainly taken from Alkire et al (2000).…”

Section: Macroscopic Effectsfmodification Of Thalamocortical Loop Actmentioning

confidence: 92%

Mechanisms of Anesthesia: Towards Integrating Network, Cellular, and Molecular Level Modeling

Århem

Klement

Nilsson

2003

Neuropsychopharmacol

View full text Add to dashboard Cite

The mechanisms of anesthesia are surprisingly little understood. The present article summarizes current knowledge about the function of general anesthetics at different organization levels of the nervous system. It argues that a consensus view can be constructed, assuming that general anesthetics modulate the activity of ion channels, the main targets being GABA and NMDA channels and possibly voltagegated and background channels, thereby hyperpolarizing neurons in thalamocortical loops, which lead to disruption of coherent oscillatory activity in the cortex. Two computational cases are used to illustrate the possible importance of molecular level effects on cellular level activity. Subtle differences in the mechanism of ion channel block can be shown to cause considerable differences in the modification of the oscillatory activity in a single neuron, and consequently in an associated network. Finally, the relation between the anesthesia problem and the classical consciousness problem is discussed, and some consequences of introducing the phenomenon of degeneracy into the picture are pointed out.

show abstract

“…Furthermore, masking a stimulus is efficient when presented with a latency of less than 100 ms (Libet, 1981); see also (Dehaene et al, 2003). Additional studies have reported similar durations for episodes of synchronous thalamo-cortical activity (Llinas and Ribary, 1998), sequences of alpha bursts (Williamson et al, 1996), and EPSP-IPSP sequences in mammalian forebrain neurons (Purpura, 1972) reviewed in (John, 2001 …”

Section: Microstates and The Phenomenon Of Discrete Epochs Of Cognitionmentioning

confidence: 94%

EEG microstates as a tool for studying the temporal dynamics of whole-brain neuronal networks: A review

2018

View full text Add to dashboard Cite

SummaryThe present review discusses a well-established method for characterizing resting-state activity of the human brain using multichannel electroencephalography (EEG). This method involves the examination of electrical microstates in the brain, which are defined as successive short time periods during which the configuration of the scalp potential field remains semi-stable, suggesting quasi-simultaneity of activity among the nodes of largescale networks. A few prototypic microstates, which occur in a repetitive sequence across time, can be reliably identified across participants. Researchers have proposed that these microstates represent the basic building blocks of the chain of spontaneous conscious mental processes, and that their occurrence and temporal dynamics determine the quality of mentation. Several studies have further demonstrated that disturbances of mental processes associated with neurological and psychiatric conditions manifest as changes in the temporal dynamics of specific microstates. Combined EEG-fMRI studies and EEG source imaging studies have indicated that EEG microstates are closely associated with resting-state networks as identified using fMRI. The scale-free properties of the time series of EEG microstates explain why similar networks can be observed at such different time scales.The present review will provide an overview of these EEG microstates, available methods for analysis, the functional interpretations of findings regarding these microstates, and their behavioral and clinical correlates.

show abstract

A Field Theory of Consciousness

Cited by 186 publications

References 70 publications

Attention to Odor Modulates Thalamocortical Connectivity in the Human Brain

Attention to Odor Modulates Thalamocortical Connectivity in the Human Brain

Mechanisms of Anesthesia: Towards Integrating Network, Cellular, and Molecular Level Modeling

EEG microstates as a tool for studying the temporal dynamics of whole-brain neuronal networks: A review

Contact Info

Product

Resources

About