Spontaneous Fluctuations and Non-linear Ignitions: Two Dynamic Faces of Cortical Recurrent Loops

Moutard, Clément; Dehaene, Stanislas; Malach, Rafael

doi:10.1016/j.neuron.2015.09.018

Cited by 101 publications

(102 citation statements)

References 119 publications

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“…These results are important because they extend the previously reported findings of failure to become aware of specific V1 activation patterns (16), to high-order visual areas, whose activity has been consistently demonstrated to be more closely linked to perceptual awareness (45,46). Together, these findings argue against the suggestion that the slow spontaneous fluctuations reflect stream of conscious thoughts and images, but rather that this activity remains largely subliminal (47)(48)(49).…”

Section: Increased Activation In High-order Areas Does Not Necessarilysupporting

confidence: 78%

Covert neurofeedback without awareness shapes cortical network spontaneous connectivity

Ramot

Grossman

Friedman

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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102

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Recent advances in blood oxygen level-dependent-functional MRI (BOLD-fMRI)-based neurofeedback reveal that participants can modulate neuronal properties. However, it is unknown whether such training effects can be introduced in the absence of participants' awareness that they are being trained. Here, we show unconscious neurofeedback training, which consequently produced changes in functional connectivity, introduced in participants who received positive and negative rewards that were covertly coupled to activity in two category-selective visual cortex regions. The results indicate that brain networks can be modified even in the complete absence of intention and awareness of the learning situation, raising intriguing possibilities for clinical interventions.neurofeedback | training | reward | spontaneous activity | functional connectivity T here has been a growing interest in the field of neuroscience in the use of neurofeedback (NF) as a tool to both study and treat various clinical conditions. The uses of NF are diverse, ranging across a variety of motor and sensory tasks (1-4), investigation of cortical plasticity and attention (5-9), to treatment of chronic pain, depression, and mood control (10-13).Recent advances in functional MRI (fMRI) techniques and hardware have made real-time fMRI (rtfMRI) a viable method for NF (14). This enables more anatomically specific training compared with methods such as EEG. This enhanced localization additionally allows to provide feedback to differential activation patterns (6, 15, 16), beyond simple up/down-regulation of a specific region/frequency.Another advance in the field of NF is the finding by several recent studies that participants are able to learn to successfully perform the NF paradigm, even without being given an explicit strategy (8,16). This form of implicit learning is intriguing, both because there have been reports indicating certain advantages to implicit over explicit learning (17,18), but mostly because this opens up previously unidentified pathways for therapeutic intervention, for cases for which there are no specific explicit strategies available (for instance, control over complex networks, such as in epilepsy, or over brain regions whose function is not fully elucidated).However, an important common factor in all previous NF studies was the fact that participants were aware that they were being trained, and received specific goals for this training. A fundamental question that therefore remains unanswered is whether targeted brain networks can still be modulated even in the complete absence of participants' awareness that a training process is taking place. Theories of closed-loop learning provide evidence that such implicit learning through reward cues is possible (19,20). This is an important issue, because it may open the way for NF training even in severe clinical cases such as minimally conscious or vegetative state, where such awareness is absent.In the present study, we examined this question in fMRI experiments in which participants were i...

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Section: Increased Activation In High-order Areas Does Not Necessarilysupporting

confidence: 78%

Covert neurofeedback without awareness shapes cortical network spontaneous connectivity

Ramot

Grossman

Friedman

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

102

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“…The recognition of the "default mode" network (26) started a long-lasting interest in the significance of the human brain's ongoing or intrinsic activity, which is characterized by synchronous USFs of activity, often taking seconds to develop (18). USFs have been recorded in the cortex of awake humans and primates, and also under anesthesia (27)(28)(29)(30).…”

Section: Resultsmentioning

confidence: 99%

“…Recordings in humans indicate that ongoing activity constantly fluctuates in a tightly correlated manner across distant brain regions, forming reproducible patterns with rich temporal dynamics and spatial organization (18). The potential contribution of spontaneous activity to conscious processing has been suggested and simulations helped characterize two main modes of activity: an active mode characterized by rapid and sustained activity ("ignition") (19), which contributes to the signature of "conscious access," and a resting mode with spontaneous ultraslow (<0.1 Hz) fluctuations (USFs) (18). It has been suggested that ignition and ultraslow spontaneous fluctuations share similar mechanisms (18).…”

mentioning

confidence: 99%

“…The potential contribution of spontaneous activity to conscious processing has been suggested and simulations helped characterize two main modes of activity: an active mode characterized by rapid and sustained activity ("ignition") (19), which contributes to the signature of "conscious access," and a resting mode with spontaneous ultraslow (<0.1 Hz) fluctuations (USFs) (18). It has been suggested that ignition and ultraslow spontaneous fluctuations share similar mechanisms (18). Independently, electrophysiological recordings in animal models have distinguished "up" and "down" states (20), and the possibility is considered here that up states coincide with USFs in humans.…”

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confidence: 99%

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Nicotinic receptors in mouse prefrontal cortex modulate ultraslow fluctuations related to conscious processing

Koukouli

Rooy

Changeux

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The prefrontal cortex (PFC) plays an important role in cognitive processes, including access to consciousness. The PFC receives significant cholinergic innervation and nicotinic acetylcholine receptors (nAChRs) contribute greatly to the effects of acetylcholine signaling. Using in vivo two-photon imaging of both awake and anesthetized mice, we recorded spontaneous, ongoing neuronal activity in layer II/III in the PFC of WT mice and mice deleted for different nAChR subunits. As in humans, this activity is characterized by synchronous ultraslow fluctuations and neuronal synchronicity is disrupted by light general anesthesia. Both the α7 and β2 nAChR subunits play an important role in the generation of ultraslow fluctuations that occur to a different extent during quiet wakefulness and light general anesthesia. The β2 subunit is specifically required for synchronized activity patterns. Furthermore, chronic application of mecamylamine, an antagonist of nAChRs, disrupts the generation of ultraslow fluctuations. Our findings provide new insight into the ongoing spontaneous activity in the awake and anesthetized state, and the role of cholinergic neurotransmission in the orchestration of cognitive functions.

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“…If this feed-forward spread or 'ignition' does not happen, conscious perception does not occur [45]. If it does happen, a great deal of arguably unconscious processing takes place in the global workspace, before ...…”

Section: 32mentioning

confidence: 99%

Consciousness Is a Thing, Not a Process

Pockett

2017

Applied Sciences

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Featured Application: If the theory outlined here is correct, the construction of artificial consciousness will certainly be possible, but a fundamentally different approach from that currently used in work on artificial intelligence will be necessary. Abstract:The central dogma of cognitive psychology is 'consciousness is a process, not a thing'. Hence, the main task of cognitive neuroscientists is generally seen as working out what kinds of neural processing are conscious and what kinds are not. I argue here that the central dogma is simply wrong. All neural processing is unconscious. The illusion that some of it is conscious results largely from a failure to separate consciousness per se from a number of unconscious processes that normally accompany it-most particularly focal attention. Conscious sensory experiences are not processes at all. They are things: specifically, spatial electromagnetic (EM) patterns, which are presently generated only by ongoing unconscious processing at certain times and places in the mammalian brain, but which in principle could be generated by hardware rather than wetware. The neurophysiological mechanisms by which putatively conscious EM patterns are generated, the features that may distinguish conscious from unconscious patterns, the general principles that distinguish the conscious patterns of different sensory modalities and the general features that distinguish the conscious patterns of different experiences within any given sensory modality are all described. Suggestions for further development of this paradigm are provided.

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Spontaneous Fluctuations and Non-linear Ignitions: Two Dynamic Faces of Cortical Recurrent Loops

Cited by 101 publications

References 119 publications

Covert neurofeedback without awareness shapes cortical network spontaneous connectivity

Covert neurofeedback without awareness shapes cortical network spontaneous connectivity

Nicotinic receptors in mouse prefrontal cortex modulate ultraslow fluctuations related to conscious processing

Consciousness Is a Thing, Not a Process

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