Experimental Model of Cerebral Arterial Air Embolism in Conscious Rats.

In this work, an optimal air supply mode was selected to create a model of cerebral arterial air embolism (CAAE) on conscious male Sprague-Dawley rats (n=49). The efficacy of the selected model (administration of 100 µl/kg of air at a rate of 10 µl/min with an infusion pump) was determined by changes in serum biochemical parameters (cholesterol, alkaline phosphatase, inorganic phosphates, AST, and triglycerides), impaired motor functions in the Rotarod test, and visual assessment of the ischemic foci (staining of frontal sections with 1% triphenyltetrazolium chloride solution) at different terms after AAE. The model of AAE created by us confirmed impairment of coordination and motor function in conscious animals and reproduced the lethal consequences of this condition. The obtained results can serve as the basis for drug testing and the development of new approaches to the treatment of ischemic stroke.

Propofol-mediated loss of consciousness disrupts predictive routing and local field phase modulation of neural activity.

Predictive coding is a fundamental function of the cortex. The predictive routing model proposes a neurophysiological implementation for predictive coding. Predictions are fed back from the deep-layer cortex via alpha/beta (8 to 30 Hz) oscillations. They inhibit the gamma (40 to 100 Hz) and spiking that feed sensory inputs forward. Unpredicted inputs arrive in circuits unprepared by alpha/beta, resulting in enhanced gamma and spiking. To test the predictive routing model and its role in consciousness, we collected data from intracranial recordings of macaque monkeys during passive presentation of auditory oddballs before and after propofol-mediated loss of consciousness (LOC). In line with the predictive routing model, alpha/beta oscillations in the awake state served to inhibit the processing of predictable stimuli. Propofol-mediated LOC eliminated alpha/beta modulation by a predictable stimulus in the sensory cortex and alpha/beta coherence between sensory and frontal areas. As a result, oddball stimuli evoked enhanced gamma power, late period (>200 ms from stimulus onset) spiking, and superficial layer sinks in the sensory cortex. LOC also resulted in diminished decodability of pattern-level prediction error signals in the higher-order cortex. Therefore, the auditory cortex was in a disinhibited state during propofol-mediated LOC. However, despite these enhanced feedforward responses in the auditory cortex, there was a loss of differential spiking to oddballs in the higher-order cortex. This may be a consequence of a loss of within-area and interareal spike-field coupling in the alpha/beta and gamma frequency bands. These results provide strong constraints for current theories of consciousness.

Role of Heart Rate, Acidosis, Consciousness, Oxygenation, and Respiratory Rate Score in Predicting Outcomes of Noninvasive Ventilation in Chronic Obstructive Pulmonary Disease Patients.

BACKGROUND: In patients with chronic obstructive pulmonary disease (COPD), early detection of noninvasive ventilation (NIV) failure is a promising technique for decreasing mortality. The objective of this study was to evaluate the efficacy of heart rate, acidosis, consciousness, oxygenation, and respiratory rate (HACOR) score in predicting NIV outcome in COPD-associated respiratory failure. METHODOLOGY: A prospective observational study was conducted on 100 COPD patients with acute respiratory failure who were initiated on NIV. HACOR score was calculated at the start of NIV and after 1-2, 12, and 24 hours. NIV failure was defined as progression to invasive mechanical ventilation or death. NIV success was defined as liberation from NIV prior to hospital day seven and not meeting criteria for failure. RESULTS: In this study, 100 patients with COPD and respiratory failure were enrolled. Their mean age was 65.34 years [standard deviation (SD) 8.19]. Male patients were predominant (n = 81). Eighty-nine percent of patients were smokers, and the remaining had exposure to biomass fuel. At the initiation of NIV, the median HACOR score was 3 (interquartile: 2, 4). In 13% of patients, there was NIV failure. There were 17 (17%) patients whose HACOR score at initiation was ≥5. In patients with a HACOR score ≥5, the NIV failure rate was 76.4% and mortality was 41.1%. The area under the curve (AUC) for prediction of NIV failure by HACOR score at initiation was 0.980 (p-value < 0.05). CONCLUSION: The HACOR score had high sensitivity as well as specificity at initiation in the prediction of NIV failure. A higher HACOR score predicts a high chance of NIV failure. Obtaining the HACOR score at the bedside makes it convenient for assessing the efficacy of NIV in patients with COPD.

The evolutionary and neurobiological attributes of consciousness: an update. / Ewolucyjne i neurobiologiczne atrybuty swiadomosci: aktualizacja.

Consciousness is most frequently defined as a subjective experience of mental processes. The phenomenon of consciousness has always been a subject of great interest in various fields of science, including psychiatry, and the most prominent scientists have engaged in research on it. The studies performed in recent years have brought about novel data on the evolutionary and neurobiological attributes of this phenomenon. In the first part of the article, the evolutionary concepts of consciousness are presented, going back to the beginnings of life on our planet. They are proposed by such illustrious scientists as Joseph LeDoux, Daniel Dennett, António Damásio, and Arthur Reber. Each of them presents the issue of consciousness in the context of evolution slightly differently. However, there are many similarities concerning the development of the nervous system and mental life. The second part discusses the novel research on the cognitive and neurobiological components of consciousness. Among many researchers of this issue, we chose the achievements of two British authors such as Chris Frith and Anil Seth. The neuroanatomical and perceptive aspects of both the level and context of consciousness are provided. Besides presenting the contemporary evolutionary and neurobiological concepts of consciousness, the article aims to bring closer the profiles of the prominent researchers of neuroscience mentioned here. This term can be translated into Polish as "neuronauka", although our country's most frequently used name is "neurobiologia."

Propofol disrupts the functional core-matrix architecture of the thalamus in humans.

Research into the role of thalamocortical circuits in anesthesia-induced unconsciousness is difficult due to anatomical and functional complexity. Prior neuroimaging studies have examined either the thalamus as a whole or focused on specific subregions, overlooking the distinct neuronal subtypes like core and matrix cells. We conducted a study of heathy volunteers and functional magnetic resonance imaging during conscious baseline, deep sedation, and recovery. We advanced the functional gradient mapping technique to delineate the functional geometry of thalamocortical circuits, within a framework of the unimodal-transmodal functional axis of the cortex. Here we show a significant shift in this geometry during deep sedation, marked by a transmodal-deficient geometry. This alteration is closely linked to the spatial variations in the matrix cell composition within the thalamus. This research bridges cellular and systems-level understanding, highlighting the crucial role of thalamic core-matrix functional architecture in understanding the neural mechanisms of states of consciousness.

Statistical Learning Facilitates Access to Awareness.

Statistical learning is a powerful mechanism that enables the rapid extraction of regularities from sensory inputs. Although numerous studies have established that statistical learning serves a wide range of cognitive functions, it remains unknown whether statistical learning impacts conscious access. To address this question, we applied multiple paradigms in a series of experiments (N = 153 adults): Two reaction-time-based breaking continuous flash suppression (b-CFS) experiments showed that probable objects break through suppression faster than improbable objects. A preregistered accuracy-based b-CFS experiment showed higher localization accuracy for suppressed probable (versus improbable) objects under identical presentation durations, thereby excluding the possibility of processing differences emerging after conscious access (e.g., criterion shifts). Consistent with these findings, a supplemental visual-masking experiment reaffirmed higher localization sensitivity to probable objects over improbable objects. Together, these findings demonstrate that statistical learning alters the competition for scarce conscious resources, thereby potentially contributing to established effects of statistical learning on higher-level cognitive processes that require consciousness.

Superconscious processes as mental images of a higher order (in the context of telezombification).

OBJECTIVE: Aim: The paper aims to examine superconscious processes as mental images of a higher order in the context of telezombification. PATIENTS AND METHODS: Materials and Methods: The authors used interpretive research paradigm, psychoanalysis, basic principles of hermeneutics, phenomenological approach along with general scientific methods, such as induction, deduction, generalization, etc. CONCLUSION: Conclusions: With the beginning of the russian full-scale attack on Ukraine, russian atrocities in Bucha, Mariupol and other cities and villages of the country, many Ukrainian citizens asked about what has happened to the russian society, the state authorities, who set the goal of destroying Ukraine as a state and all its inhabitants as a nation. Then Ukrainians have labelled the invaders and the authorities of Russia as non-humans. And this is a fair name for them. The fact is that these occupiers and their neo-Nazi leaders have a destroyed, distorted consciousness as a result of which they became incapable of realizing their thought processes. The consciousness of such persons gradually degrades towards animal thinking, the so-called proto-thinking. This is one direction to not realizing one's intentions and actions at the level of both subconscious and partially conscious analysis of primary mental images (images of a first and second orders). The second direction is the role of superconscious processes, in particular mental images of a higher level, which also form the worldview positions of an individual in the process of viewing and listening to certain information, while remaining, at the same time, unconscious until a certain time. Together, these directions form a person's attitude to existing social and worldview problems.

Interoceptive signals shape the earliest markers and neural pathway to awareness at the visual threshold.

Variations in interoceptive signals from the baroreceptors (BRs) across the cardiac and respiratory cycle can modulate cortical excitability and so affect awareness. It remains debated at what stages of processing they affect awareness-related event-related potentials (ERPs) in different sensory modalities. We investigated the influence of the cardiac (systole/diastole) and the respiratory (inhalation/exhalation) phase on awareness-related ERPs. Subjects discriminated visual threshold stimuli while their electroencephalogram, electrocardiogram, and respiration were simultaneously recorded. We compared ERPs and their intracranial generators for stimuli classified correctly with and without awareness as a function of the cardiac and respiratory phase. Cyclic variations of interoceptive signals from the BRs modulated both the earliest electrophysiological markers and the trajectory of brain activity when subjects became aware of the stimuli: an early sensory component (P1) was the earliest marker of awareness for low (diastole/inhalation) and a perceptual component (visual awareness negativity) for high (systole/exhalation) BR activity, indicating that BR signals interfere with the sensory processing of the visual input. Likewise, activity spread from the primary visceral cortex (posterior insula) to posterior parietal cortices during high and from associative interoceptive centers (anterior insula) to the prefrontal cortex during low BR activity. Consciousness is thereby resolved in cognitive/associative regions when BR is low and in perceptual centers when it is high. Our results suggest that cyclic fluctuations of BR signaling affect both the earliest markers of awareness and the brain processes underlying conscious awareness.

Elements of episodic memory: lessons from 40 years of research.

40 years ago, Endel Tulving published his hugely influential Elements of Episodic Memory (Oxford: Clarendon Press, 1983). For the first time, this discussed the details of episodic memory (i.e. the ability to remember personal past events), including a specific conscious experience. Ten years later, Tulving defined the ability to mentally project oneself in time to be the critical feature distinguishing episodic from semantic memory ('What is episodic memory?' Curr. Dir. Psychol. Sci. 2, 67-70, doi:10.1111/1467-8721.ep10770899). In this conception, the conscious experience of episodic memory captures the experience of reliving a personal event as it was experienced in the past, while the same ability allows a potential symmetry between remembering the past, and our ability to project into an imagined future. With the recent passing of Endel Tulving, this theme issue offers an opportunity to question our understanding of mental time travel in full.This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

Episodic memory without autonoetic consciousness.

Ever since Tulving's influential 1985 article 'Memory and consciousness', it has become traditional to think of autonoetic consciousness as necessary for episodic memory. This paper questions this claim. Specifically, it argues that the construct of autonoetic consciousness lacks validity and that, even if it was valid, it would still not be necessary for episodic memory. The paper ends with a proposal to go back to a functional/computational characterization of episodic memory in which its characteristic phenomenology is a contingent feature of the retrieval process and, as a result, open to empirical scrutiny. The proposal also dovetails with recent taxonomies of memory that are independent of conscious awareness and suggests strategies to evaluate within- and between-individual variability in the conscious experience of episodic memories in human and non-human agents. This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

Sense of Agency during Encoding Predicts Subjective Reliving.

Autonoetic consciousness (ANC), the ability to re-experience personal past events links episodic memory and self-consciousness by bridging awareness of oneself in a past event (i.e., during its encoding) with awareness of oneself in the present (i.e., during the reliving of a past event). Recent neuroscience research revealed a bodily form of self-consciousness, including the sense of agency (SoA) and the sense of body ownership (SoO) that are based on the integration of multisensory bodily inputs and motor signals. However, the relation between SoA and/or SoO with ANC is not known. Here, we used immersive virtual reality technology and motion tracking and investigated the potential association of SoA/SoO with ANC. For this, we exposed participants to different levels of visuomotor and perspectival congruency, known to modulate SoA and SoO, during the encoding of virtual scenes and collected ANC ratings 1 week after the encoding session. In a total of 74 healthy participants, we successfully induced systematic changes in SoA and SoO during encoding and found that ANC depended on the level of SoA experienced during encoding. Moreover, ANC was positively associated with SoA, but only for the scene encoded with preserved visuomotor and perspectival congruency, and such SoA-ANC coupling was absent for SoO and control questions. Collectively, these data provide behavioral evidence in a novel paradigm that links a key subjective component of bodily self-consciousness during encoding, SoA, to the subjective reliving of those encoded events from one's past, ANC.

No evidence for unconscious initiation and following of arithmetic rules: A replication study.

The field of consciousness studies has yielded various-sometimes contradicting-accounts regarding the function of consciousness, ranging from denying it has such function to claiming that any high-level cognitive function requires consciousness. Empirical findings supporting both accounts were reported, yet some of them have been recently revisited based on failures to replicate. Here, we aimed at replicating a remarkable finding reported by Ric and Muller (2012); participants were able to follow an unseen instruction, integrate it with a subsequently presented pair of unseen digits, and accordingly either add the digits (resulting in a priming effect), or simply represent them. This finding thus demonstrates unconscious task-switching, temporal integration (involving mental chaining), and arithmetic operation. Finding such high-level processes in the absence of awareness is of pivotal importance to our understanding of consciousness, as it challenges prominent theories in the field (e.g., the global neuronal workspace). Accordingly, in light of the self-correction wave in psychological science in general and in the field of consciousness studies in particular, we report here a preregistered replication aimed at testing the reproducibility of this finding, while also better controlling for subjects' awareness of both the instruction and the digits. Across two highly powered experiments, our results failed to replicate the original effect. We, therefore, conclude that the current evidence does not support the claim that arithmetic operations (specifically, addition) can be flexibly initiated without awareness, in line with the current arguments for a more limited scope of unconscious processing. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

When sensory input meets spontaneous brain activity.

A recent study by Wu, Podvalny, and colleagues investigated how ongoing spontaneous brain activity interacts with sensory input and shapes conscious perception. It reports diverse effects of prestimulus activity in several key networks, revealing new roles of the prefrontal cortex and the default mode network in perception and consciousness.

[Current progress on characteristics of intracranial electrophysiology related to prolonged disorders of consciousness].

Prolonged disorders of consciousness (pDOC) are pathological conditions of alterations in consciousness caused by various severe brain injuries, profoundly affecting patients' life ability and leading to a huge burden for both the family and society. Exploring the mechanisms underlying pDOC and accurately assessing the level of consciousness in the patients with pDOC provide the basis of developing therapeutic strategies. Research of non-invasive functional neuroimaging technologies, such as functional magnetic resonance (fMRI) and scalp electroencephalography (EEG), have demonstrated that the generation, maintenance and disorders of consciousness involve functions of multiple cortical and subcortical brain regions, and their networks. Invasive intracranial neuroelectrophysiological technique can directly record the electrical activity of subcortical or cortical neurons with high signal-to-noise ratio and spatial resolution, which has unique advantages and important significance for further revealing the brain function and disease mechanism of pDOC. Here we reviewed the current progress of pDOC research based on two intracranial electrophysiological signals, spikes reflecting single-unit activity and field potential reflecting multi-unit activities, and then discussed the current challenges and gave an outlook on future development, hoping to promote the study of pathophysiological mechanisms related to pDOC and provide guides for the future clinical diagnosis and therapy of pDOC.

Index of Consciousness monitoring may effectively predict and prevent circulatory stress induced by endotracheal intubation under general anesthesia: a prospective randomized controlled trial.

BACKGROUND: The primary objective of anesthesiologists during the induction of anaesthesia is to mitigate the operative stress response resulting from endotracheal intubation. In this prospective, randomized controlled trial, our aim was to assess the feasibility and efficacy of employing Index of Consciousness (IoC, IoC1 and IoC2) monitoring in predicting and mitigating circulatory stress induced by endotracheal intubation for laparoscopic cholecystectomy patients under general anesthesia (GA). METHODS: We enrolled one hundred and twenty patients scheduled for laparoscopic cholecystectomy under GA and randomly allocated them to two groups: IoC monitoring guidance (Group T, n = 60) and bispectral index (BIS) monitoring guidance (Group C, n = 60). The primary endpoints included the heart rate (HR) and mean arterial pressure (MAP) of the patients, as well as the rate of change (ROC) at specific time points during the endotracheal intubation period. Secondary outcomes encompassed the systemic vascular resistance index (SVRI), cardiac output index (CI), stroke volume index (SVI), ROC at specific time points, the incidence of adverse events (AEs), and the induction dosage of remifentanil and propofol during the endotracheal intubation period in both groups. RESULTS: The mean (SD) HR at 1 min after intubation under IoC monitoring guidance was significantly lower than that under BIS monitoring guidance (76 (16) beats/min vs. 82 (16) beats/min, P = 0.049, respectively). Similarly, the mean (SD) MAP at 1 min after intubation under IoC monitoring guidance was lower than that under BIS monitoring guidance (90 (20) mmHg vs. 98 (19) mmHg, P = 0.031, respectively). At each time point from 1 to 5 min after intubation, the number of cases with HR ROC of less than 10% in Group T was significantly higher than in Group C (P < 0.05). Furthermore, between 1 and 3 min and at 5 min post-intubation, the number of cases with HR ROC between 20 to 30% or 40% in Group T was significantly lower than that in Group C (P < 0.05). At 1 min post-intubation, the number of cases with MAP ROC of less than 10% in Group T was significantly higher than that in Group C (P < 0.05), and the number of cases with MAP ROC between 10 to 20% in Group T was significantly lower than that in Group C (P < 0.01). Patients in Group T exhibited superior hemodynamic stability during the peri-endotracheal intubation period compared to those in Group C. There were no significant differences in the frequencies of AEs between the two groups (P > 0.05). CONCLUSION: This promising monitoring technique has the potential to predict the circulatory stress response, thereby reducing the incidence of adverse reactions during the peri-endotracheal intubation period. This technology holds promise for optimizing anesthesia management. TRAIL REGISTRATION:  Chinese Clinical Trail Registry Identifier: ChiCTR2300070237 (20/04/2022).

Dynamical structure-function correlations provide robust and generalizable signatures of consciousness in humans.

Resting-state functional magnetic resonance imaging evolves through a repertoire of functional connectivity patterns which might reflect ongoing cognition, as well as the contents of conscious awareness. We investigated whether the dynamic exploration of these states can provide robust and generalizable markers for the state of consciousness in human participants, across loss of consciousness induced by general anaesthesia or slow wave sleep. By clustering transient states of functional connectivity, we demonstrated that brain activity during unconsciousness is dominated by a recurrent pattern primarily mediated by structural connectivity and with a reduced capacity to transition to other patterns. Our results provide evidence supporting the pronounced differences between conscious and unconscious brain states in terms of whole-brain dynamics; in particular, the maintenance of rich brain dynamics measured by entropy is a critical aspect of conscious awareness. Collectively, our results may have significant implications for our understanding of consciousness and the neural basis of human awareness, as well as for the discovery of robust signatures of consciousness that are generalizable among different brain conditions.

Breathwork-induced psychedelic experiences modulate neural dynamics.

Breathwork is an understudied school of practices involving intentional respiratory modulation to induce an altered state of consciousness (ASC). We simultaneously investigate the phenomenological and neural dynamics of breathwork by combining Temporal Experience Tracing, a quantitative methodology that preserves the temporal dynamics of subjective experience, with low-density portable EEG devices. Fourteen novice participants completed a course of up to 28 breathwork sessions-of 20, 40, or 60 min-in 28 days, yielding a neurophenomenological dataset of 301 breathwork sessions. Using hypothesis-driven and data-driven approaches, we found that "psychedelic-like" subjective experiences were associated with increased neural Lempel-Ziv complexity during breathwork. Exploratory analyses showed that the aperiodic exponent of the power spectral density-but not oscillatory alpha power-yielded similar neurophenomenological associations. Non-linear neural features, like complexity and the aperiodic exponent, neurally map both a multidimensional data-driven composite of positive experiences, and hypothesis-driven aspects of psychedelic-like experience states such as high bliss.