From the origins to the stream of consciousness and its neural correlates

Abstract

There are now dozens of very different theories of consciousness, each somehow contributing to our understanding of its nature. The science of consciousness needs therefore not new theories but a general framework integrating insights from those, yet not making it a still-born "Frankenstein" theory. First, the framework must operate explicitly on the stream of consciousness, not on its static description. Second, this dynamical account must also be put on the evolutionary timeline to explain the origins of consciousness. The Cognitive Evolution Theory (CET), outlined here, proposes such a framework. This starts with the assumption that brains have primarily evolved as volitional subsystems of organisms, inherited from primitive (fast and random) reflexes of simplest neural networks, only then resembling error-minimizing prediction machines. CET adopts the tools of critical dynamics to account for metastability, scale-free avalanches, and self-organization which are all intrinsic to brain dynamics. This formalizes the stream of consciousness as a discrete (transitive, irreflexive) chain of momentary states derived from critical brain dynamics at points of phase transitions and mapped then onto a state space as neural correlates of a particular conscious state. The continuous/discrete dichotomy appears naturally between the brain dynamics at the causal level and conscious states at the phenomenal level, each volitionally triggered from arousal centers of the brainstem and cognitively modulated by thalamocortical systems. Their objective observables can be entropy-based complexity measures, reflecting the transient level or quantity of consciousness at that moment.

Keywords: brain dynamics; complexity; criticality; evolution; quantum; stream of consciousness; volition.

Figure 1

Brain criticality and conscious experience. (A) In large-scale brain dynamics, conscious states emerge at critical points near phase transitions between synchronization (order) and desynchronization (disorder) patterns of neural activity at the microscale. (B) The map m transforms each critical point of brain dynamics, described in a phase space, onto the whole-brain network 𝒩 in a vector space as a particular NCC responsible for a certain conscious state at that moment of time. (C) The stream of consciousness can then be formalized as a discrete chain of states (N-dimensional vectors) and studied in causal dynamical modeling as a directed acyclic graph. (D) In neural pleiotropy, many neurons constitute a particular NCC for producing a certain conscious percept, thereby involving a single neuron in generating very different percepts. (E) Conscious experience is a product of unconscious computations initiated by the brainstem at the hard level and accomplished by various thalamocortical systems at the soft level.

Figure 2

Critical dynamics, phase transitions and the NFVM. (A) In critical dynamics, one neuron excites another and causes avalanches of activity spreading across 𝒩 and obeying the power law of distribution. The brain exhibits a broad range of flexible patterns of coordinated dynamics which decay after some critical value. While the NFVM initiates avalanches from arousal centers, a decentralized feedback mechanism arises spontaneously to lead a self-organized system from subcritical to supercritical phases. (B) A simulation of critical phase transitions on the 2D Ising spin lattice model exhibits different degrees of synchronization or coordination (black dots) from subcritical to supercritical states as temperature (a control parameter) increases from left to right. Adopted from Kitzbichler et al. (2009). Complexity as an entropy-based measure placed between two thermodynamic extrema: a perfect crystal at absolute zero temperature and an ideal gas. C_𝒩 reflects a mixture of integration/segregation in brain dynamics with maximal values near criticality between subcritical and supercritical phases presented above.

Figure 3

The origins of consciousness. CET starts from the assumption that the brain should have primarily evolved as volitional subsystems of organisms from simplest neural reflexes based on chemoreceptor, magneto- and photoreceptor cells sensitive to quantum effects. At the causal (hard) level, the volitional subsystems should provide a principled psyche-matter division between organisms, exploiting their stimulus-reactions repertoires freely, and non-living systems, governed completely by cause-effects interactions. Placing the NFVM into the brainstem, the oldest brain region that integrates functions of many vital systems and is responsible for arousal and vigilance guarantees that each conscious state will be triggered free of predetermination from the past.