Frontiers in systems neuroscience
January 1, 2019
Tom Sikkens, Conrado A Bosman, Umberto Olcese
48 citations
Feedback connections, which make up a large portion of neural links in the thalamocortical system, are thought to be essential for conscious perception, according to major theories of consciousness. These theories predict that feedback modulation should be reduced in nonconscious brain states such as non-REM sleep and anesthesia, and when sensory stimuli are not perceived. However, recent experiments on mismatch negativity, a phenomenon linked to top-down modulation, show that feedback modulation persists during nonconscious states, though it is generally dampened. These deviations challenge current theories and may require reevaluating how consciousness is assessed in supposedly nonconscious states.
Frontiers in systems neuroscience
January 1, 2021
Giorgio Vallortigara
34 citations
Animals distinguish self-generated from externally caused sensory input using an efference copy mechanism, a copy of movement commands sent to sensory structures. This paper links that mechanism to philosopher Thomas Reid's idea that senses have a double province: to make us feel and to make us perceive. Psychologist Nicholas Humphrey argued that the former identifies with signals from bodily sense organs combined with an internalized evaluative response, i.e., phenomenal consciousness. The author discusses a possible departure from the classical efference copy implementation that could provide senses with such a double province, potentially advancing understanding of consciousness.
Frontiers in systems neuroscience
January 1, 2022
Sidney Carls-Diamante
28 citations
Octopuses may experience a unique form of consciousness that diverges from human understanding. Their nervous system, comprising over 500 million neurons, is decentralized, allowing each arm to operate independently. Remarkably, severed arms continue to display behaviors akin to those of the intact animal, suggesting an autonomous consciousness. This hints at the concept of "multiple consciousness," where both the octopus and its arms possess distinct experiences. Thus, the octopus consciousness may encompass not just the whole being but also individual arms—an intriguing notion in the study of sentience.
Frontiers in systems neuroscience
January 1, 2021
Matthew N Van de Poll, Bruno van Swinderen
23 citations
The brain’s ability to predict is vital, yet it must also adapt to surprises. Emotional responses to unexpected events can significantly influence memory consolidation, with positive or negative cues shaping internal models of the world. In a study involving diverse species, including invertebrates, it was proposed that active sleep—characterized by REM—is crucial for optimizing predictive processing. This mechanism may help maintain a balance between prediction and surprise, providing insights into the evolution of consciousness across various animals.
Frontiers in systems neuroscience
January 1, 2019
Evert A. Boonstra, Heleen A. Slagter
19 citations
The article argues that Karl Friston's free energy minimization framework, which claims to unify brain theory and apply to all living systems, aligns with Georg Hegel's dialectics. Drawing on Catherine Malabou's work, the authors demonstrate that Friston's approach reinvigorates Hegelian dialectics from a neuroscience perspective, requiring a reading through Hegel's speculative philosophy. This reading moves beyond the cognitivism-enactivism debate about whether organisms are secluded from or open to their surroundings. Instead, the tension between these positions is itself operative at the organismic level as a contradiction the organism sustains throughout life: secluded existence depends on perpetual relation with surroundings, and the condition for that relation is a secluded entity. This internalized contradiction grounds the perpetual process of free energy minimization.
Frontiers in systems neuroscience
January 1, 2022
Thurston Lacalli
9 citations
Conscious experience can be modeled as occupying a high-dimensional space (E-space) whose dimensions correspond to the degrees of freedom needed to specify sets of qualia. Phenomenal consciousness likely originated as one or more multidimensional ur-experiences that combined multiple forms of experience. Evolution then extracted the qualia best suited to each sensory modality through a process called dimensional sorting. This framework provides a systematic way to think about early stages in the evolution of consciousness, moving beyond narrative and conjecture alone.
Frontiers in systems neuroscience
January 1, 2022
Brian Key, Oressia Zalucki, Deborah J Brown
9 citations
Subjective experience—conscious awareness—requires a specific neural architecture, not merely activity in higher cortical regions. The authors propose that any system capable of subjective experience must implement stacked forward models that predict the output of neural processing from inputs, enabling prediction, error detection, and feedback control. They call this the hierarchical forward models algorithm. This framework defines a minimal but not sufficient neural architecture necessary for subjective experience. It implies that animals lacking this architecture cannot have subjective experience, regardless of behavior or brain similarities to humans. The approach shifts focus from which brain regions are active to what computations are performed.
Frontiers in systems neuroscience
January 1, 2022
Paul Skokowski
9 citations
Explaining qualia—the subjective contents of conscious experience—within a naturalistic framework is challenging. Examining Behaviorism, Identity Theory, Functionalism, and Integrated Information Theory reveals each fails to adequately account for qualia. To overcome this, the senses should be interpreted as physical detectors. A new theory, Grounded Functionalism, is proposed that preserves multiple realizability while providing a scientifically grounded approach to explaining qualia in the natural world.
Frontiers in systems neuroscience
January 1, 2022
Uziel Awret
A novel dual-aspect theory of consciousness is proposed, grounded in the principle of holographic duality from modern physics. The theory aims to provide consciousness-independent explanations for anti-physicalist intuitions about representational content and spatial location, while setting aside the hard problem and phenomenal character. The author argues that abstract algorithms are insufficient and that a more radical form of computation, inspired by physics and realizable in strange metals, may be required. This approach could establish necessary connections between structural aspects of conscious mental states and their physical substrate, and explain why representational content is not spatially located. The paper ends by reconsidering the conceivability of zombies.
Frontiers in systems neuroscience
January 1, 2022
Daniel Revach, Moti Salti
Understanding the mind and its relation to the body depends on how consciousness is defined. The authors argue that an information-theory perspective offers a unified and parsimonious account. They present consciousness as the propagation of information from the past to the future, contrasting with dominant models that treat it as a discrete brain function. Using this lens, they demonstrate that temporal continuity in perception can explain the emergence of volition, subjectivity, higher-order thoughts, and body boundaries without additional assumptions. The work discusses implications for the mind-body question and the appeal of embodied cognition.
Frontiers in systems neuroscience
January 1, 2022
Günter Ehret, Raymond Romand
Neural markers of consciousness derived from human event-related potentials and gamma-wave activity can be applied to other species. In mammals and birds, these markers suggest that individuals in these groups can become subjectively aware of and conscious about perceived stimuli. For fish, cephalopods, and insects, the data remain inconclusive. Awareness and consciousness appear as evolved, attention-dependent options added to ongoing stimulus processing and action generation. Because gamma-wave generation for functional coupling of brain areas in conscious states is energetically costly, it remains to be shown which species gain reproductive fitness advantages from these options. The discussion begins with whether these brain activities are necessary for adaptive stimulus perception and response.
Frontiers in systems neuroscience
January 1, 2021
Yali Chen, Jun Zhang
Consciousness is thought to arise from specific neuronal processes, but leading theories like information integration theory, global neuronal workspace theory, and the temporospatial theory focus on neural mechanisms while neglecting their energetic-metabolic basis. Drawing on findings from loss of consciousness due to sleep, general anesthesia, and vegetative state/unresponsive wakeful syndrome in humans and animals, the authors propose that energetic-metabolic processes involving ATP, glucose, and γ-aminobutyrate/glutamate are essential for the functional connectivity of normal brain networks that enables consciousness. They describe these as energetic-metabolic predispositions of consciousness, complementing existing theories centered on neural correlates.
Frontiers in systems neuroscience
January 1, 2021
Thurston Lacalli
Conscious experience likely evolved from simple beginnings, gaining complexity over time as new categories of subjective experience were added. The simplest, most fundamental contents—qualia—resist further analysis and can be represented as points, lines, or curves on a topological experience space, distinct from more complex experiences called formats (e.g., vision, language) that depend on algorithmic processes or memory. Qualia correspond to domains in a configuration space representing a subset of neural correlates of consciousness called selector circuits (SCs), which ensure a particular experience is evoked.
Frontiers in systems neuroscience
January 1, 2020
Chiara Mazzi, Gaetano Mazzeo, Silvia Savazzi
Contrastive analysis of EEG data is used to identify neural correlates of consciousness, but it may be confounded by processes before or after conscious perception. To isolate visual awareness from post-perceptual decision-making, participants performed an orientation discrimination task while shifting their response criterion across sessions. The N1 and P3 components were sensitive to the response criterion, and their modulation increased with criterion shifts, indicating involvement in decision-making independent of awareness. When ignoring the response criterion, both Visual Awareness Negativity (VAN) and Late Positivity (LP) were significant for aware versus unaware contrasts.
Frontiers in systems neuroscience
January 1, 2019
Julia Moser, Siouar Bensaid, Eleni Kroupi et al.
Information-based metrics of neural activity can help quantify consciousness before and shortly after birth. Using fetal magnetoencephalography (fMEG) in human fetuses and neonates, researchers evaluated measures of entropy, compressibility, and fractality. Lempel-Ziv-Complexity (LZC) was the most practical metric because it is unequivocal and requires low computational effort, whereas fractality and entropy measures need more parameter adjustments. Comparing a brain-activity channel with a control channel in neonates showed significant differences in most complexity metrics, serving as proof of concept. For fetal data, results were less clear, possibly due to leftover maternal signals. The inconsistency across metrics highlights challenges in using complexity metrics as neural correlates of consciousness.
Frontiers in systems neuroscience
January 1, 2019
Matthew Owen, Mihretu P Guta
The concept of neural correlates of consciousness (NCC) is central to the scientific study of consciousness. Chalmers's influential definition holds that NCC are minimally sufficient for consciousness, but the meaning of sufficiency requires clarification. This article analyzes three relevant types of sufficiency—logical, metaphysical, and physical—and proposes a theoretical approach to consciousness studies based on the appropriate sense of sufficiency. The authors argue that their conception of NCC has important implications for research methodology, neuroethics, and the ongoing search for NCC.