The Temporally-Integrated Causality Landscape: Reconciling Neuroscientific Theories With the Phenomenology of Consciousness

In recent years, there has been a proliferation of neuroscientific theories of consciousness. These include theories which explicitly point to EM fields, notably Operational Architectonics and, more recently, the General Resonance Theory. In phenomenological terms, human consciousness is a unified composition of contents. These contents are specific and meaningful, and they exist from a subjective point of view. Human conscious experience is temporally continuous, limited in content, and coherent. Based upon those phenomenal observations, pre-existing theories of consciousness, and a large body of experimental evidence, I derived the Temporally-Integrated Causality Landscape (TICL). In brief, the TICL proposes that the neural correlate of consciousness is a structure of temporally integrated causality occurring over a large portion of the thalamocortical system. This structure is composed of a large, integrated set of neuronal elements (the System), which contains some subsystems, defined as having a higher level of temporally-integrated causality than the System as a whole. Each Subsystem exists from the point of view of the System, in the form of meaningful content. In this article, I review the TICL and consider the importance of EM forces as a mechanism of neural causality. I compare the fundamentals of TICL to those of several other neuroscientific theories. Using five major characteristics of phenomenal consciousness as a standard, I compare the basic tenets of Integrated Information Theory, Global Neuronal Workspace, General Resonance Theory, Operational Architectonics, and the Temporo-spatial Theory of Consciousness with the framework of the TICL. While the literature concerned with these theories tends to focus on different lines of evidence, there are fundamental areas of agreement. This means that, in time, it may be possible for many of them to converge upon the truth. In this analysis, I conclude that a primary distinction which divides these theories is the feature of spatial and temporal nesting. Interestingly, this distinction does not separate along the fault line between theories explicitly concerned with EM fields and those which are not. I believe that reconciliation is possible, at least in principle, among those theories that recognize the following: just as the contents of consciousness are distinctions within consciousness, the neural correlates of conscious content should be distinguishable from but fall within the spatial and temporal boundaries of the full neural correlates of consciousness.

The search for the NCC: Progress and challenges

Twenty years ago, Thomas Metzinger published the book "The Neural Correlates of Consciousness" amassing the state of knowledge in the field of consciousness studies at the time from philosophical and empirical perspectives. On the occasion of the 20th anniversary of this impactful publication, we review the progress the field has made since then and the important methodological challenges it faces. A tremendous number of empirical studies have been conducted, which has led to the identification of many candidate neural correlates of consciousness. Yet, this tremendous amount of work has not unraveled a consensual account of consciousness as of now. Many questions, some already raised twenty years ago, remain unanswered, and an enormous proliferation of theories sharply contrasts with the scarcity of compelling data and methodological challenges. The contrastive method, the foundational method used to study the neural correlate of consciousness (NCC), has also been called into question. And while awareness in the community of its shortcomings is widespread, few concrete attempts have been made to go beyond it and/or to revise existing theories. We propose several methodological shifts that we believe may help to advance the quest of the NCC program, while remaining uncommitted to any specific theory: (1) the currently prevalent “contrastive method” should lose its monopoly in favor of methods that attempt to explain the phenomenology of experience; (2) experimental data should be shared in centralized, multi-methods databases, transcending the limitations of individual experiments by granting granularity and power to generalize findings and “distill” the NCC proper; (3) the explanatory power of theories should be directly pitted against each other to overcome the non-productive fractioning of the field into insular camps seeking confirmatory evidence for their theories. We predict these innovations might enable the field to progress towards the goal of explaining consciousness.

A new no-report paradigm reveals that face cells encode both consciously perceived and suppressed stimuli

A powerful paradigm to identify neural correlates of consciousness is binocular rivalry, wherein a constant visual stimulus evokes a varying conscious percept. It has recently been suggested that activity modulations observed during rivalry may represent the act of report rather than the conscious percept itself. Here, we performed single-unit recordings from face patches in macaque inferotemporal (IT) cortex using a no-report paradigm in which the animal’s conscious percept was inferred from eye movements. We found that large proportions of IT neurons represented the conscious percept even without active report. Furthermore, on single trials we could decode both the conscious percept and the suppressed stimulus. Together, these findings indicate that (1) IT cortex possesses a true neural correlate of consciousness and (2) this correlate consists of a population code wherein single cells multiplex representation of the conscious percept and veridical physical stimulus, rather than a subset of cells perfectly reflecting consciousness.

Reorganization of the connectivity between elementary functions as a common mechanism of phenomenal consciousness and working memory: from functions to strategies

In the present communication, phenomenal consciousness, access consciousness and the closely related concept of working memory are presented in the context of a neurocognitive model—the REF (reorganization of elementary functions) framework. The REF framework is based on connectionist networks within which the ‘units’ are advanced processing modules called elementary functions (EFs). In this framework, the focus is on dynamically changeable ‘strategies’—based on reorganizations of the connectivity between EFs—rather than on the more traditional ‘cognitive functions’. The background for the REF framework and especially how the neural correlate of consciousness is understood within these models is summarized. According to the REF framework, phenomenal consciousness cannot ‘overflow’ availability of information for action. Phenomenal consciousness may, however, overflow working memory because working memory in the present context is seen as a surface phenomenon reflecting underlying dynamic strategies—influenced by both experience and situational factors. This article is part of the theme issue ‘Perceptual consciousness and cognitive access'.

Can binocular rivalry reveal neural correlates of consciousness?

This essay critically examines the extent to which binocular rivalry can provide important clues about the neural correlates of conscious visual perception. Our ideas are presented within the framework of four questions about the use of rivalry for this purpose: (i) what constitutes an adequate comparison condition for gauging rivalry's impact on awareness, (ii) how can one distinguish abolished awareness from inattention, (iii) when one obtains unequivocal evidence for a causal link between a fluctuating measure of neural activity and fluctuating perceptual states during rivalry, will it generalize to other stimulus conditions and perceptual phenomena and (iv) does such evidence necessarily indicate that this neural activity constitutes a neural correlate of consciousness? While arriving at sceptical answers to these four questions, the essay nonetheless offers some ideas about how a more nuanced utilization of binocular rivalry may still provide fundamental insights about neural dynamics, and glimpses of at least some of the ingredients comprising neural correlates of consciousness, including those involved in perceptual decision-making.

Three comments on Teller’s “bridge locus”

The notion of a set of neurons that form a “bridge locus” serving as the immediate substrate of visual perception is examined in the light of evidence on the architecture of the visual pathway, of current thinking about perceptual representations, and of the basis of perceptual awareness. The bridge locus is likely to be part of a tangled web of representations, and this complexity raises the question of whether another scheme that relies less on geography might offer a better framework. The bridge locus bears a close relationship to the neural correlate of consciousness (NCC), and like the NCC may be a concept which is no longer precise enough to provide a useful basis for reasoning about the relationship between brain activity and perceptual experience.