Neuroscience of Consciousness最新文献

The Perturbation Complexity Index-State Transitions (PCI^ST) measures the complexity of the brain's response to transcranial magnetic stimulation (TMS) using electroencephalography (EEG) and is sensitive to consciousness, such as minimally conscious states. Individuals with early-stage Alzheimer's disease (AD) show dysfunction of conscious processes, such as attention, working memory, episodic memory, and executive function, with relatively spared unconscious processes, such as procedural memory, operant conditioning, and priming. We sought to test the hypothesis that PCI^ST would be reduced in AD compared to healthy aging. We assessed 28 participants with AD and 27 healthy controls (HC), measuring cognition with the Montreal Cognitive Assessment (MoCA) and disease severity with the Clinical Dementia Rating scale-Global (CDR-Global) and Sum of Boxes (CDR-SB). Results indicated lower PCI^ST in the AD group (M = 20.1) compared to controls (M = 28.2) across both the motor cortex (M1) and inferior parietal lobule (IPL) TMS stimulation sites, suggesting that PCI^ST may reflect the impaired conscious cognitive processes and functional capacity seen in AD. We therefore speculate that cortical dementias involve alterations in cortical complexity that may relate to deterioration of their conscious processes. This research opens the avenue for future studies in individuals with cortical dementia to examine the relationship between conscious processes, global measures of consciousness, and their underlying neuroanatomical correlates, in addition to enhancing our understanding of dementia and suggesting possible therapeutic strategies.

Non-dual awareness (NDA) refers to a shift in consciousness in which the usual distinction between subject and object dissolves, and experience is no longer structured by conceptual mediation or goal-directed regulation. Meling enactivist model describes NDA as a meditative disclosure of groundlessness-the recognition of emptiness (śūnyatā), that all phenomena lack intrinsic nature. While enactivism explains autonomy through process closure, this article argues that constraint closure, as developed by Nave, extends that framework by making explicit how autonomy is sustained through the continual regeneration of its own relational conditions. This refinement prevents process-closure models from being read in substantialist terms when applied to complex cognitive systems, where stability arises through ongoing transformation rather than fixed organization. Nave's account builds on Juarrero theory of constraint causality, which replaces intrinsic forces with relational conditions-a view that parallels Nāgārjuna's Madhyamaka analysis of dependent origination. Integrating these perspectives, I propose that NDA corresponds to a shift from decoupled to precarious constraints, revealing that cognition and awareness persist not through intrinsic foundations but through the dynamic regeneration of interdependent relations.

Contingency awareness refers to an observer's ability to identify the association between a conditioned and an unconditioned stimulus (US). A widely held belief in human fear conditioning is that this form of associative learning may occur independently of contingency awareness. To test this hypothesis, in this preregistered study (https://osf.io/vywq7), we recorded electroencephalography during a task, where participants were presented with compounds of a word (drawn from two semantic categories) and tactile stimulation (vibration), followed by either a neutral sound (US-) or a loud noise (US+). Based on interviews, participants were divided into an aware (N = 50) and an unaware (N = 31) group. Only the aware group showed evidence of learning at the neural level, notably a larger stimulus-preceding negativity developing before US+ and a stronger theta response to vibrations predicting the US+. The aware group also showed stronger alpha and beta suppression around the vibrations and a weaker theta response to US+, possibly indicating heightened attention to the cue and the violation/confirmation of expectation. Group differences in alpha and beta suppression were already present before the aversive learning began, suggesting that elevated attention may precede and facilitate awareness. Personality tests showed that elevated anxiety, neuroticism, higher intolerance of uncertainty, or harm avoidance is not predictive of the acquisition of contingency awareness. Our findings support the notion that fear conditioning, as reflected in cortical measures, cannot occur without contingency awareness.

Visual imagery and external perception rely on similar representations. However, whether the same processes underpin the subjective appraisal of both percepts and mental images is not yet known. One well-known effect in perceptual detection tasks is that people take longer to report perceptions of absence compared to presence. Vividness reports are detection-like in that participants report the presence or absence of a mental image. We therefore asked whether reports of low vividness share commonalities with reports of target absence. Across five pre-existing datasets, we report a robust inverse correlation between imagery vividness ratings and reaction times: participants take longer to report the vividness of mental images when they are weak. In addition, in one of the two datasets that included detection tasks and trait imagery questionnaires we find that individual differences in detection asymmetries (slower responses for absence versus presence in detection tasks) and trait imagery can predict the strength of this vividness-response time relationship. Our results may be suggestive of a shared mechanism employed across both perception and imagery that evaluates the strength of visual experience. Future research is necessary to fully characterize the mechanisms driving this effect.

For individuals with sound-touch synesthesia, sounds consistently evoke strong, localized sensations on the body. We systematically investigated the relationship between sound frequency and the characteristics of induced tactile experiences in synesthetes (n = 19) and controls (n = 23). Sound frequency strongly predicted the location of tactile sensations in synesthetes and controls. Synesthetes experienced touch more frequently and tended to report sensations in more spatially focused regions of the body, reflecting a sharper mapping between sound frequency and somatotopy. This spatial distribution of touch according to sound frequency reflects a behavioral mapping between tonotopy and somatotopy suggesting the involvement of early, tonotopically- and somatotopically-organized brain areas. These findings highlight a strong similarity between auditory-tactile mappings in synesthetic and ordinary perception, suggesting that synesthesia only differs in the strength of the mappings and therefore may be on a spectrum with ordinary perception. Furthermore, these findings offer insights into the neural mechanisms of sound-touch mappings, suggesting they rely on cross-modal neural pathways utilized in ordinary perception.

It has been proposed that both conscious and unconscious perception are associated with a feedforward sweep of oscillatory activity in the gamma band (>40 Hz), while conscious perception also requires recurrent feedback via beta band ([Formula: see text]20 Hz) oscillations. To investigate the causal relationship between these oscillations and (un)conscious visual perception, we assessed the effect of transcranial alternating current stimulation (tACS) in the gamma (40 Hz) and beta (20 Hz) bands on the objective and subjective visibility of targets in a metacontrast backward masking task. To capture different aspects of visual experience, we measured objective visibility: participants' ability to correctly categorize the masked stimulus, and subjective visibility: participants' self-report of whether they consciously perceived the stimulus. We expected that 40hz-tACS would affect both the objective visibility and subjective visibility. Moreover, we expected that 20 Hz-tACS would selectively affect the subjective visibility. Our results showed that target visibility was selectively compromised by 20 Hz-tACS but, in contrast to our hypothesis, this effect was specific to objective visibility. Although the power of local beta oscillations increased after 20 Hz-tACS, inter-areal beta synchrony could have nevertheless been impaired, a possibility that should be investigated in the future by means of source reconstructed high density electroencephalography recordings. In summary, our findings suggest that 20 Hz tACS may modulate target visibility, indicating a potential relationship between beta-band activity and visual perception. Future studies could build upon this result by investigating other forms of stimulation and other model organisms, further contributing to our knowledge of how conscious access causally depends on brain oscillations.

Although in recent years some studies have found evidence suggesting that working memory (WM) may operate on unconscious perceptual contents, decisive demonstrations of the existence of unconscious WM are lacking. In the present Registered Report, we replicate the first study on this topic by Soto et al. (Working memory without consciousness. Curr Biol 2011;21:R912-3.): a visual discrimination task asking participants to report the direction in which a subliminal Gabor grating was rotated after a 2-s delay. We acquired a multisite sample from 19 laboratories, with a larger number of participants (N = 531) and trials (720 in two sessions) than those typically used in previous studies. As a result, a large-sample, international, and open-access dataset is now available for researchers and future analyses. Furthermore, some minimal baseline requirements were guaranteed for the experimental task (i.e. number of valid trials, motivation, and consistent labels for the Perceptual Awareness Scale). The results showed (1) above-chance WM performance in cue-present trials reported as unseen (.55 accuracy), (2) a significant positive correlation between WM performance and cue detection sensitivity (r = .228), and (3) a significant above-chance intercept in the regression of performance on sensitivity (β ₀ = .521). These findings suggest that WM can operate on unconscious representations, although it remains positively associated with perceptual sensitivity. Crucially, because measurement error could compromise the interpretation of these three results, we provide evidence for our measures' excellent reliability and, more fundamentally, for their validity.

According to contemporary psycho- and physiological perspectives, the brain supports our experience of the world by constantly anticipating what may happen next. In this context, limbic mesocortical areas have been proposed to play a key domain-general role in cortical processing, holding highly abstract content that may be efficiently broadcasted to virtually the whole brain, ultimately integrating interoception into a unified field of experience from the point of view of someone who has a body. Here we ground the evolutionary basis of such structural and functional organization in the hypothesis of the dual origin of the neocortex, suggesting that the addition of phylogenetically newer cortical types with modality-specific processing may have enabled the primitive polysensory role of limbic mesocortical areas to evolve into a multimodal coordinator within an ever more complex brain, favoring the possibilities of conscious experience. Moreover, two fundamental functional axes with relevance for allostasis emerge: (i) a navigation/spatial versus exchange/contact axis; and (ii) a sensing versus acting axis. The former summarizes a fundamental distinction between spatial navigation and musculoskeletal control versus close interactions in the intimate and internal spheres; the latter reflects a functional (although intimately linked) distinction between sensory and motor aspects. These axes define a conceptual bidimensional space across cortical types where virtually all cortical areas may be placed according to their functional relevance, with limbic mesocortices ultimately integrating experience across sensory-motor function and navigation-exchange. These notions have important implications for our understanding of allostasis and human experience.

During the wake-sleep cycle, consciousness waxes and wanes, and this is thought to be reflected in varying levels of integration between brain areas. Recent studies challenged the notion that consciousness is homogeneously present or absent in a brain state, as exemplified by conscious reports found in otherwise unconscious Non-rapid eye movement (NREM) sleep. Here, we tested if functional connectivity (FC) between neurons varies within brain states in a way compatible with a fluctuating level of consciousness. We examined directed FC between neurons across the wake-sleep cycle in rats, at a scale of a few seconds. We observed that NREM sleep contains epochs in which patterns of inter-areal FC are comparable to those observed in wakefulness and REM sleep, and vice versa. Thus, circuit-level connectivity patterns are not univocally determined by the brain state in which they occur, but could rather reflect other factors such as the fluctuation in the level of consciousness that takes place not only between but also within brain states.

Lived experience is shaped by intersubjective, social, cultural, and historical dimensions. For the past 30 years, neurophenomenology has adopted an embodied perspective of the mind by integrating first-person experiential and third-person neurobehavioural perspectives. Neurophenomenology reveals mutual constraints between both, as they co-constitute a person's lived experience. This article emphasizes the intersubjective and social facets of lived experience as core to generative neurophenomenology, envisioned in the 1990s by Francisco Varela, and argues that the scientific community is now ready to adopt this approach. For this endeavour, we clarify three meanings of 'generative' as it applies distinctly to generative phenomenology, generative passages, and generative models. Then, we propose to combine existing methods to update neurophenomenology program: first, by transitioning from individual to multiple people phenomenology methods that include intersubjectivity experience; second, by expanding traditional neuroscience to include measures of multimodal interpersonal synchrony; and third, by leveraging multiple computational tools to integrate different viewpoints, thereby enriching our understanding of lived experience. We also underscore the potential of diverse mathematical formalisms to capture aspects of human experience, all while underscoring that using computational approaches to model neurophenomenology does not entail endorsing computationalism as a grounding hypothesis of human experience. Finally, we illustrate the clinical relevance of this paradigm through two case studies in psychiatry-(1) with interactive dyads in autism and (2) with multiple members in family therapy sessions-demonstrating its translational potential.