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1.
Nature ; 589(7842): 420-425, 2021 01.
Article in English | MEDLINE | ID: mdl-33361808

ABSTRACT

Everyday tasks in social settings require humans to encode neural representations of not only their own spatial location, but also the location of other individuals within an environment. At present, the vast majority of what is known about neural representations of space for self and others stems from research in rodents and other non-human animals1-3. However, it is largely unknown how the human brain represents the location of others, and how aspects of human cognition may affect these location-encoding mechanisms. To address these questions, we examined individuals with chronically implanted electrodes while they carried out real-world spatial navigation and observation tasks. We report boundary-anchored neural representations in the medial temporal lobe that are modulated by one's own as well as another individual's spatial location. These representations depend on one's momentary cognitive state, and are strengthened when encoding of location is of higher behavioural relevance. Together, these results provide evidence for a common encoding mechanism in the human brain that represents the location of oneself and others in shared environments, and shed new light on the neural mechanisms that underlie spatial navigation and awareness of others in real-world scenarios.


Subject(s)
Neurons/physiology , Space Perception/physiology , Spatial Navigation/physiology , Adult , Awareness/physiology , Biological Clocks , Cognition/physiology , Electrodes, Implanted , Female , Humans , Male , Middle Aged , Temporal Lobe/physiology
2.
Proc Natl Acad Sci U S A ; 121(37): e2311953121, 2024 Sep 10.
Article in English | MEDLINE | ID: mdl-39226342

ABSTRACT

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.


Subject(s)
Awareness , Electroencephalography , Interoception , Humans , Male , Adult , Female , Awareness/physiology , Interoception/physiology , Evoked Potentials/physiology , Young Adult , Consciousness/physiology , Electrocardiography
3.
Proc Natl Acad Sci U S A ; 121(38): e2405973121, 2024 Sep 17.
Article in English | MEDLINE | ID: mdl-39250665

ABSTRACT

Despite growing scientific alarm about anthropogenic climate change, the world is not on track to solve the crisis. Inaction may be partially explained by skepticism about climate change and resistance to proenvironmental policies from people who are motivated to maintain the status quo (i.e., conservative-rightists). Therefore, practical interventions are needed. In the present research program, we tested an experimental manipulation derived from system justification theory in which proenvironmental initiatives were framed as patriotic and necessary to maintain the American "way of life." In a large, nationally representative U.S. sample, we found that the system-sanctioned change intervention successfully increased liberal-leftists' as well as conservative-rightists' belief in climate change; support for proenvironmental policies; and willingness to share climate information on social media. Similar messages were effective in an aggregated analysis involving 63 countries, although the overall effect sizes were small. More granular exploratory analyses at the country level revealed that while the intervention was moderately successful in some countries (e.g., Brazil, France, Israel), it backfired in others (Germany, Belgium, Russia). Across the three outcome variables, the effects of the intervention were consistent and pronounced in the United States, in support of the hypothesis that system justification motivation can be harnessed on behalf of social change. Potential explanations for divergent country-level effects are discussed. The system-sanctioned change intervention holds considerable promise for policymakers and communicators seeking to increase climate awareness and action.


Subject(s)
Climate Change , United States , Humans , Awareness , Environmental Policy , Politics , Public Opinion
4.
Proc Natl Acad Sci U S A ; 120(39): e2303590120, 2023 09 26.
Article in English | MEDLINE | ID: mdl-37729196

ABSTRACT

Site-specific proteolysis by the enzymatic cleavage of small linear sequence motifs is a key posttranslational modification involved in physiology and disease. The ability to robustly and rapidly predict protease-substrate specificity would also enable targeted proteolytic cleavage by designed proteases. Current methods for predicting protease specificity are limited to sequence pattern recognition in experimentally derived cleavage data obtained for libraries of potential substrates and generated separately for each protease variant. We reasoned that a more semantically rich and robust model of protease specificity could be developed by incorporating the energetics of molecular interactions between protease and substrates into machine learning workflows. We present Protein Graph Convolutional Network (PGCN), which develops a physically grounded, structure-based molecular interaction graph representation that describes molecular topology and interaction energetics to predict enzyme specificity. We show that PGCN accurately predicts the specificity landscapes of several variants of two model proteases. Node and edge ablation tests identified key graph elements for specificity prediction, some of which are consistent with known biochemical constraints for protease:substrate recognition. We used a pretrained PGCN model to guide the design of protease libraries for cleaving two noncanonical substrates, and found good agreement with experimental cleavage results. Importantly, the model can accurately assess designs featuring diversity at positions not present in the training data. The described methodology should enable the structure-based prediction of specificity landscapes of a wide variety of proteases and the construction of tailor-made protease editors for site-selectively and irreversibly modifying chosen target proteins.


Subject(s)
Endopeptidases , Peptide Hydrolases , Peptide Hydrolases/genetics , Proteolysis , Awareness , Machine Learning
5.
J Neurosci ; 44(8)2024 Feb 21.
Article in English | MEDLINE | ID: mdl-38191569

ABSTRACT

Identifying neural correlates of conscious perception is a fundamental endeavor of cognitive neuroscience. Most studies so far have focused on visual awareness along with trial-by-trial reports of task-relevant stimuli, which can confound neural measures of perceptual awareness with postperceptual processing. Here, we used a three-phase sine-wave speech paradigm that dissociated between conscious speech perception and task relevance while recording EEG in humans of both sexes. Compared with tokens perceived as noise, physically identical sine-wave speech tokens that were perceived as speech elicited a left-lateralized, near-vertex negativity, which we interpret as a phonological version of a perceptual awareness negativity. This response appeared between 200 and 300 ms after token onset and was not present for frequency-flipped control tokens that were never perceived as speech. In contrast, the P3b elicited by task-irrelevant tokens did not significantly differ when the tokens were perceived as speech versus noise and was only enhanced for tokens that were both perceived as speech and relevant to the task. Our results extend the findings from previous studies on visual awareness and speech perception and suggest that correlates of conscious perception, across types of conscious content, are most likely to be found in midlatency negative-going brain responses in content-specific sensory areas.


Subject(s)
Awareness , Speech Perception , Male , Female , Humans , Awareness/physiology , Visual Perception/physiology , Electroencephalography/methods , Speech , Consciousness/physiology
6.
J Neurosci ; 44(34)2024 Aug 21.
Article in English | MEDLINE | ID: mdl-39048314

ABSTRACT

Recent studies suggest that time estimation relies on bodily rhythms and interoceptive signals. We provide the first direct electrophysiological evidence suggesting an association between the brain's processing of heartbeat and duration judgment. We examined heartbeat-evoked potential (HEP) and contingent negative variation (CNV) during an auditory duration-reproduction task and a control reaction-time task spanning 4, 8, and 12 s intervals, in both male and female participants. Interoceptive awareness was assessed with the Self-Awareness Questionnaire (SAQ) and interoceptive accuracy through the heartbeat-counting task (HCT). Results revealed that SAQ scores, but not the HCT, correlated with mean reproduced durations with higher SAQ scores associating with longer and more accurate duration reproductions. Notably, the HEP amplitude changes during the encoding phase of the timing task, particularly within 130-270 ms (HEP1) and 470-520 ms (HEP2) after the R-peak, demonstrated interval-specific modulations that did not emerge in the control task. A significant ramp-like increase in HEP2 amplitudes occurred during the duration-encoding phase of the timing but not during the control task. This increase within the reproduction phase of the timing task correlated significantly with the reproduced durations for the 8 s and the 4 s intervals. The larger the increase in HEP2, the greater the under-reproduction of the estimated duration. CNV components during the encoding phase of the timing task were more negative than those in the reaction-time task, suggesting greater executive resources orientation toward time. We conclude that interoceptive awareness (SAQ) and cortical responses to heartbeats (HEP) predict duration reproductions, emphasizing the embodied nature of time.


Subject(s)
Brain , Electroencephalography , Heart Rate , Interoception , Time Perception , Humans , Male , Female , Time Perception/physiology , Heart Rate/physiology , Young Adult , Adult , Interoception/physiology , Brain/physiology , Awareness/physiology , Evoked Potentials/physiology , Reaction Time/physiology , Contingent Negative Variation/physiology
7.
J Neurosci ; 44(20)2024 May 15.
Article in English | MEDLINE | ID: mdl-38531633

ABSTRACT

A central question in consciousness theories is whether one is dealing with a dichotomous ("all-or-none") or a gradual phenomenon. In this 7T fMRI study, we investigated whether dichotomy or gradualness in fact depends on the brain region associated with perceptual awareness reports. Both male and female human subjects performed an emotion discrimination task (fear vs neutral bodies) presented under continuous flash suppression with trial-based perceptual awareness measures. Behaviorally, recognition sensitivity increased linearly with increased stimuli awareness and was at chance level during perceptual unawareness. Physiologically, threat stimuli triggered a slower heart rate than neutral ones during "almost clear" stimulus experience, indicating freezing behavior. Brain results showed that activity in the occipitotemporal, parietal, and frontal regions as well as in the amygdala increased with increased stimulus awareness while early visual areas showed the opposite pattern. The relationship between temporal area activity and perceptual awareness best fitted a gradual model while the activity in frontoparietal areas fitted a dichotomous model. Furthermore, our findings illustrate that specific experimental decisions, such as stimulus type or the approach used to evaluate awareness, play pivotal roles in consciousness studies and warrant careful consideration.


Subject(s)
Awareness , Frontal Lobe , Magnetic Resonance Imaging , Parietal Lobe , Temporal Lobe , Humans , Male , Female , Magnetic Resonance Imaging/methods , Awareness/physiology , Parietal Lobe/physiology , Parietal Lobe/diagnostic imaging , Adult , Frontal Lobe/physiology , Frontal Lobe/diagnostic imaging , Young Adult , Temporal Lobe/physiology , Temporal Lobe/diagnostic imaging , Brain Mapping/methods , Photic Stimulation/methods , Emotions/physiology
8.
Cereb Cortex ; 34(6)2024 Jun 04.
Article in English | MEDLINE | ID: mdl-38863114

ABSTRACT

When reminded of an unpleasant experience, people often try to exclude the unwanted memory from awareness, a process known as retrieval suppression. Here we used multivariate decoding (MVPA) and representational similarity analyses on EEG data to track how suppression unfolds in time and to reveal its impact on item-specific cortical patterns. We presented reminders to aversive scenes and asked people to either suppress or to retrieve the scene. During suppression, mid-frontal theta power within the first 500 ms distinguished suppression from passive viewing of the reminder, indicating that suppression rapidly recruited control. During retrieval, we could discern EEG cortical patterns relating to individual memories-initially, based on theta-driven visual perception of the reminders (0 to 500 ms) and later, based on alpha-driven reinstatement of the aversive scene (500 to 3000 ms). Critically, suppressing retrieval weakened (during 360 to 600 ms) and eventually abolished item-specific cortical patterns, a robust effect that persisted until the reminder disappeared (780 to 3000 ms). Representational similarity analyses provided converging evidence that retrieval suppression weakened the representation of target scenes during the 500 to 3000 ms reinstatement window. Together, rapid top-down control during retrieval suppression abolished cortical patterns of individual memories, and precipitated later forgetting. These findings reveal a precise chronometry on the voluntary suppression of individual memories.


Subject(s)
Awareness , Electroencephalography , Mental Recall , Humans , Male , Female , Young Adult , Adult , Awareness/physiology , Mental Recall/physiology , Consciousness/physiology , Memory/physiology , Visual Perception/physiology , Brain/physiology
9.
Cereb Cortex ; 34(6)2024 Jun 04.
Article in English | MEDLINE | ID: mdl-38850216

ABSTRACT

Whether attention is a prerequisite of perceptual awareness or an independent and dissociable process remains a matter of debate. Importantly, understanding the relation between attention and awareness is probably not possible without taking into account the fact that both are heterogeneous and multifaceted mechanisms. Therefore, the present study tested the impact on visual awareness of two attentional mechanisms proposed by the Posner model: temporal alerting and spatio-temporal orienting. Specifically, we evaluated the effects of attention on the perceptual level, by measuring objective and subjective awareness of a threshold-level stimulus; and on the neural level, by investigating how attention affects two postulated event-related potential correlates of awareness. We found that alerting and orienting mechanisms additively facilitate perceptual consciousness, with activation of the latter resulting in the most vivid awareness. Furthermore, we found that late positivity is unlikely to constitute a neural correlate of consciousness as its amplitude was modulated by both attentional mechanisms, but early visual awareness negativity was independent of the alerting and orienting mechanisms. In conclusion, our study reveals a nuanced relationship between attention and awareness; moreover, by investigating the effect of the alerting mechanism, this study provides insights into the role of temporal attention in perceptual consciousness.


Subject(s)
Attention , Awareness , Electroencephalography , Evoked Potentials , Visual Perception , Humans , Attention/physiology , Awareness/physiology , Male , Female , Young Adult , Adult , Visual Perception/physiology , Evoked Potentials/physiology , Photic Stimulation/methods , Space Perception/physiology , Consciousness/physiology , Brain/physiology
10.
Proc Natl Acad Sci U S A ; 119(16): e2119868119, 2022 04 19.
Article in English | MEDLINE | ID: mdl-35412910

ABSTRACT

The sensation of internal bodily signals, such as when your stomach is contracting or your heart is beating, plays a critical role in broad biological and psychological functions ranging from homeostasis to emotional experience and self-awareness. The evolutionary origins of this capacity and, thus, the extent to which it is present in nonhuman animals remain unclear. Here, we show that rhesus monkeys (Macaca mulatta) spend significantly more time viewing stimuli presented asynchronously, as compared to synchronously, with their heartbeats. This is consistent with evidence previously shown in human infants using a nearly identical experimental paradigm, suggesting that rhesus monkeys have a human-like capacity to integrate interoceptive signals from the heart with exteroceptive audiovisual information. As no prior work has demonstrated behavioral evidence of innate cardiac interoceptive ability in nonhuman animals, these results have important implications for our understanding of the evolution of this ability and for establishing rhesus monkeys as an animal model for human interoceptive function and dysfunction. We anticipate that this work may also provide an important model for future psychiatric research, as disordered interoceptive processing is implicated in a wide variety of psychiatric conditions.


Subject(s)
Heart Rate , Interoception , Animals , Awareness , Heart , Macaca mulatta , Models, Animal
11.
Proc Natl Acad Sci U S A ; 119(12): e2116884119, 2022 03 22.
Article in English | MEDLINE | ID: mdl-35286213

ABSTRACT

Our cognitive system is tuned toward spotting the uncommon and unexpected. We propose that individuals coming from minority groups are, by definition, just that­uncommon and often unexpected. Consequently, they are psychologically salient in perception, memory, and visual awareness. This minority salience creates a tendency to overestimate the prevalence of minorities, leading to an erroneous picture of our social environments­an illusion of diversity. In 12 experiments with 942 participants, we found evidence that the presence of minority group members is indeed overestimated in memory and perception and that masked images of minority group members are prioritized for visual awareness. These findings were consistent when participants were members of both the majority group and the minority group. Moreover, this overestimated prevalence of minorities led to decreased support for diversity-promoting policies. We discuss the theoretical implications of the illusion of diversity and how it may inform more equitable and inclusive decision-making.


Subject(s)
Awareness , Memory , Minority Groups , Perception , Bias , Humans , Minority Groups/psychology
12.
J Neurosci ; 43(40): 6760-6778, 2023 10 04.
Article in English | MEDLINE | ID: mdl-37607820

ABSTRACT

Unconscious acquisition of sequence structure from experienced events can lead to explicit awareness of the pattern through extended practice. Although the implicit-to-explicit transition has been extensively studied in humans using the serial reaction time (SRT) task, the subtle neural activity supporting this transition remains unclear. Here, we investigated whether frequency-specific neural signal transfer contributes to this transition. A total of 208 participants (107 females) learned a sequence pattern through a multisession SRT task, allowing us to observe the transitions. Session-by-session measures of participants' awareness for sequence knowledge were conducted during the SRT task to identify the session when the transition occurred. By analyzing time course RT data using switchpoint modeling, we identified an increase in learning benefit specifically at the transition session. Electroencephalogram (EEG)/magnetoencephalogram (MEG) recordings revealed increased theta power in parietal (precuneus) regions one session before the transition (pretransition) and a prefrontal (superior frontal gyrus; SFG) one at the transition session. Phase transfer entropy (PTE) analysis confirmed that directional theta transfer from precuneus → SFG occurred at the pretransition session and its strength positively predicted learning improvement at the subsequent transition session. Furthermore, repetitive transcranial magnetic stimulation (TMS) modulated precuneus theta power and altered transfer strength from precuneus to SFG, resulting in changes in both transition rate and learning benefit at that specific point of transition. Our brain-stimulation evidence supports a role for parietal → prefrontal theta signal transfer in igniting conscious awareness of implicitly acquired knowledge.SIGNIFICANCE STATEMENT There exists a pervasive phenomenon wherein individuals unconsciously acquire sequence patterns from their environment, gradually becoming aware of the underlying regularities through repeated practice. While previous studies have established the robustness of this implicit-to-explicit transition in humans, the refined neural mechanisms facilitating conscious access to implicit knowledge remain poorly understood. Here, we demonstrate that prefrontal activity, known to be crucial for conscious awareness, is triggered by neural signal transfer originating from the posterior brain region, specifically the precuneus. By employing brain stimulation techniques, we establish a causal link between neural signal transfer and the occurrence of awareness. Our findings unveil a mechanism by which implicit knowledge becomes consciously accessible in human cognition.


Subject(s)
Awareness , Learning , Female , Humans , Awareness/physiology , Learning/physiology , Prefrontal Cortex/physiology , Reaction Time/physiology , Electroencephalography
13.
J Cogn Neurosci ; 36(8): 1546-1556, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38527082

ABSTRACT

Results from paradigms like change blindness and inattentional blindness indicate that observers are unaware of numerous aspects of the visual world. However, intuition suggests that perceptual experience is richer than these results indicate. Why does it feel like we see so much when the data suggests we see so little? One possibility stems from the fact that experimental studies always present observers with stimuli that they have never seen before. Meanwhile, when forming intuitions about perceptual experience, observers reflect on their experiences with scenes with which they are highly familiar (e.g., their office). Does prior experience with a scene change the bandwidth of perceptual awareness? Here, we asked if observers were better at noticing alterations to the periphery in familiar scenes compared with unfamiliar scenes. We found that observers noticed changes to the periphery more frequently with familiar stimuli. Signal detection theoretic analyses revealed that when observers are unfamiliar with a stimulus, they are less sensitive at noticing (d') and are more conservative in their response criterion (c). Taken together, these results suggest that prior knowledge expands the bandwidth of perceptual awareness. It should be stressed that these results challenge the widely held idea that prior knowledge fills in perception. Overall, these findings highlight how prior knowledge plays an important role in determining the limits of perceptual experience and is an important factor to consider when attempting to reconcile the tension between empirical observation and personal introspection.


Subject(s)
Awareness , Recognition, Psychology , Humans , Awareness/physiology , Recognition, Psychology/physiology , Young Adult , Female , Male , Visual Perception/physiology , Adult , Photic Stimulation , Signal Detection, Psychological/physiology
14.
J Cogn Neurosci ; 36(8): 1599-1609, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38527095

ABSTRACT

Perceptual awareness in infants during the first year of life is understudied, despite the philosophical, scientific, and clinical importance of understanding how and when consciousness emerges during human brain development. Although parents are undoubtedly convinced that their infant is conscious, the lack of adequate experimental paradigms to address this question in preverbal infants has been a hindrance to research on this topic. However, recent behavioral and brain imaging studies have shown that infants are engaged in complex learning from an early age and that their brains are more structured than traditionally thought. I will present a rapid overview of these results, which might provide indirect evidence of early perceptual awareness and then describe how a more systematic approach to this question could stand within the framework of global workspace theory, which identifies specific signatures of conscious perception in adults. Relying on these brain signatures as a benchmark for conscious perception, we can deduce that it exists in the second half of the first year, whereas the evidence before the age of 5 months is less solid, mainly because of the paucity of studies. The question of conscious perception before term remains open, with the possibility of short periods of conscious perception, which would facilitate early learning. Advances in brain imaging and growing interest in this subject should enable us to gain a better understanding of this important issue in the years to come.


Subject(s)
Awareness , Humans , Infant , Awareness/physiology , Consciousness/physiology , Child Development/physiology , Brain/physiology , Brain/diagnostic imaging , Perception/physiology
15.
J Cogn Neurosci ; 36(8): 1578-1598, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38319889

ABSTRACT

Individuals with aphantasia, a nonclinical condition typically characterized by mental imagery deficits, often report reduced episodic memory. However, findings have hitherto rested largely on subjective self-reports, with few studies experimentally investigating both objective and subjective aspects of episodic memory in aphantasia. In this study, we tested both aspects of remembering in aphantasic individuals using a custom 3-D object and spatial memory task that manipulated visuospatial perspective, which is considered to be a key factor determining the subjective experience of remembering. Objective and subjective measures of memory performance were taken for both object and spatial memory features under different perspective conditions. Surprisingly, aphantasic participants were found to be unimpaired on all objective memory measures, including those for object memory features, despite reporting weaker overall mental imagery experience and lower subjective vividness ratings on the memory task. These results add to newly emerging evidence that aphantasia is a heterogenous condition, where some aphantasic individuals may lack metacognitive awareness of mental imagery rather than mental imagery itself. In addition, we found that both participant groups remembered object memory features with greater precision when encoded and retrieved in the first person versus third person, suggesting a first-person perspective might facilitate subjective memory reliving by enhancing the representational quality of scene contents.


Subject(s)
Memory, Episodic , Metacognition , Humans , Metacognition/physiology , Male , Female , Middle Aged , Imagination/physiology , Aged , Mental Recall/physiology , Adult , Awareness/physiology , Spatial Memory/physiology
16.
J Cogn Neurosci ; 36(7): 1297-1324, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38579265

ABSTRACT

It has been proposed that visual awareness negativity (VAN), which is an early ERP component, constitutes a neural correlate of visual consciousness that is independent of perceptual and cognitive mechanisms. In the present study, we investigated whether VAN is indeed a specific marker of phenomenal awareness or rather reflects the involvement of attention. To this end, we reanalyzed data collected in a previously published EEG experiment in which awareness of visual stimuli and two aspects that define attentional involvement, namely, the inherent saliency and task relevance of a stimulus, were manipulated orthogonally. During the experimental procedure, participants (n = 41) were presented with images of faces that were backward-masked or unmasked, fearful or neutral, and defined as task-relevant targets or task-irrelevant distractors. Single-trial ERP analysis revealed that VAN was highly dependent on attentional manipulations in the early time window (140-200 msec), up to the point that the effect of awareness was not observed for attentionally irrelevant stimuli (i.e., neutral faces presented as distractors). In the late time window (200-350 msec), VAN was present in all attentional conditions, but its amplitude was significantly higher in response to fearful faces and task-relevant face images than in response to neutral ones and task-irrelevant ones, respectively. In conclusion, we demonstrate that the amplitude of VAN is highly dependent on both exogenous (stimulus saliency) and endogenous attention (task requirements). Our results challenge the view that VAN constitutes an attention-independent correlate of phenomenal awareness.


Subject(s)
Attention , Consciousness , Electroencephalography , Humans , Female , Male , Attention/physiology , Consciousness/physiology , Young Adult , Adult , Photic Stimulation , Visual Perception/physiology , Evoked Potentials/physiology , Awareness/physiology , Facial Recognition/physiology , Brain/physiology
17.
Neuroimage ; 297: 120699, 2024 Aug 15.
Article in English | MEDLINE | ID: mdl-38944172

ABSTRACT

After more than 30 years of extensive investigation, impressive progress has been made in identifying the neural correlates of consciousness (NCC). However, the functional role of spatiotemporally distinct consciousness-related neural activity in conscious perception is debated. An influential framework proposed that consciousness-related neural activities could be dissociated into two distinct processes: phenomenal and access consciousness. However, though hotly debated, its authenticity has not been examined in a single paradigm with more informative intracranial recordings. In the present study, we employed a visual awareness task and recorded the local field potential (LFP) of patients with electrodes implanted in cortical and subcortical regions. Overall, we found that the latency of visual awareness-related activity exhibited a bimodal distribution, and the recording sites with short and long latencies were largely separated in location, except in the lateral prefrontal cortex (lPFC). The mixture of short and long latencies in the lPFC indicates that it plays a critical role in linking phenomenal and access consciousness. However, the division between the two is not as simple as the central sulcus, as proposed previously. Moreover, in 4 patients with electrodes implanted in the bilateral prefrontal cortex, early awareness-related activity was confined to the contralateral side, while late awareness-related activity appeared on both sides. Finally, Granger causality analysis showed that awareness-related information flowed from the early sites to the late sites. These results provide the first LFP evidence of neural correlates of phenomenal and access consciousness, which sheds light on the spatiotemporal dynamics of NCC in the human brain.


Subject(s)
Awareness , Consciousness , Humans , Consciousness/physiology , Male , Female , Adult , Awareness/physiology , Visual Perception/physiology , Electrocorticography , Brain/physiology , Young Adult , Electrodes, Implanted , Prefrontal Cortex/physiology
18.
Neuroimage ; 298: 120805, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39173692

ABSTRACT

The study of the neural substrates that serve conscious vision is one of the unsolved questions of cognitive neuroscience. So far, consciousness literature has endeavoured to disentangle which brain areas and in what order are involved in giving rise to visual awareness, but the problem of consciousness still remains unsolved. Availing of two different but complementary sources of data (i.e., Fast Optical Imaging and EEG), we sought to unravel the neural dynamics responsible for the emergence of a conscious visual experience. Our results revealed that conscious vision is characterized by a significant increase of activation in extra-striate visual areas, specifically in the Lateral Occipital Complex (LOC), and that, more interestingly, such activity occurred in the temporal window of the ERP component commonly thought to represent the electrophysiological signature of visual awareness, i.e., the Visual Awareness Negativity (VAN). Furthermore, Granger causality analysis, performed to further investigate the flow of activity occurring in the investigated areas, unveiled that neural processes relating to conscious perception mainly originated in LOC and subsequently spread towards visual and motor areas. In general, the results of the present study seem to advocate for an early contribution of LOC in conscious vision, thus suggesting that it could represent a reliable neural correlate of visual awareness. Conversely, striate visual areas, showing awareness-related activity only in later stages of stimulus processing, could be part of the cascade of neural events following awareness emergence.


Subject(s)
Consciousness , Electroencephalography , Occipital Lobe , Visual Perception , Humans , Consciousness/physiology , Visual Perception/physiology , Male , Female , Adult , Young Adult , Occipital Lobe/physiology , Occipital Lobe/diagnostic imaging , Primary Visual Cortex/physiology , Primary Visual Cortex/diagnostic imaging , Brain Mapping , Evoked Potentials, Visual/physiology , Visual Cortex/physiology , Visual Cortex/diagnostic imaging , Awareness/physiology
19.
Br J Cancer ; 130(11): 1795-1802, 2024 May.
Article in English | MEDLINE | ID: mdl-38555316

ABSTRACT

BACKGROUND: Modifying public awareness of oesophageal cancer symptoms might help to decrease late-stage diagnosis and, in turn, improve cancer outcomes. This study aimed to explore oesophageal cancer symptom awareness and determinants of lower awareness and anticipated time to help-seeking. METHODS: We invited 18,156 individuals aged 18 to 75 years using random sampling of the nationwide Dutch population registry. A cross-sectional web-based survey containing items adapted from the Awareness and Beliefs about Cancer measure (i.e., cancer symptom awareness, anticipated time to presentation with dysphagia, health beliefs, and sociodemographic variables) was filled out by 3106 participants (response rate: 17%). Descriptive statistics were calculated and logistic regression analyses were performed to explore determinants of awareness and anticipated presentation (dichotomised as <1 month or ≥1 month). RESULTS: The number of participants that recognised dysphagia as a potential symptom of cancer was low (47%) compared with symptoms of other cancer types (change in bowel habits: 77%; change of a mole: 93%; breast lump: 93%). In multivariable analyses, non-recognition of dysphagia was associated with male gender (OR 0.50, 95% CI 0.43-0.58), lower education (OR 0.44, 0.35-0.54), and non-western migration background (OR 0.43, 0.28-0.67). Anticipated delayed help-seeking for dysphagia was associated with not recognising it as possible cancer symptom (OR 1.58, 1.27-1.97), perceived high risk of oesophageal cancer (OR 2.20, 1.39-3.47), and negative beliefs about oesophageal cancer (OR 1.86, 1.20-2.87). CONCLUSION: Our findings demonstrate a disconcertingly low public awareness of oesophageal cancer symptoms. Educational interventions targeting groups with decreased awareness and addressing negative cancer beliefs may lead to faster help-seeking behaviour, although additional studies are needed to determine the effect on clinical cancer outcomes.


Subject(s)
Esophageal Neoplasms , Health Knowledge, Attitudes, Practice , Patient Acceptance of Health Care , Humans , Esophageal Neoplasms/epidemiology , Esophageal Neoplasms/psychology , Male , Middle Aged , Female , Adult , Aged , Cross-Sectional Studies , Adolescent , Young Adult , Patient Acceptance of Health Care/statistics & numerical data , Surveys and Questionnaires , Deglutition Disorders/epidemiology , Awareness , Time Factors , Netherlands/epidemiology , Help-Seeking Behavior
20.
Hum Brain Mapp ; 45(10): e26786, 2024 Jul 15.
Article in English | MEDLINE | ID: mdl-38994692

ABSTRACT

Whether in performing arts, sporting, or everyday contexts, when we watch others move, we tend to enjoy bodies moving in synchrony. Our enjoyment of body movements is further enhanced by our own prior experience with performing those movements, or our 'embodied experience'. The relationships between movement synchrony and enjoyment, as well as embodied experience and movement enjoyment, are well known. The interaction between enjoyment of movements, synchrony, and embodiment is less well understood, and may be central for developing new approaches for enriching social interaction. To examine the interplay between movement enjoyment, synchrony, and embodiment, we asked participants to copy another person's movements as accurately as possible, thereby gaining embodied experience of movement sequences. Participants then viewed other dyads performing the same or different sequences synchronously, and we assessed participants' recognition of having performed these sequences, as well as their enjoyment of each movement sequence. We used functional near-infrared spectroscopy to measure cortical activation over frontotemporal sensorimotor regions while participants performed and viewed movements. We found that enjoyment was greatest when participants had mirrored the sequence and recognised it, suggesting that awareness of embodiment may be central to enjoyment of synchronous movements. Exploratory analyses of relationships between cortical activation and enjoyment and recognition implicated the sensorimotor cortices, which subserve action observation and aesthetic processing. These findings hold implications for clinical research and therapies seeking to foster successful social interaction.


Subject(s)
Awareness , Pleasure , Sensorimotor Cortex , Spectroscopy, Near-Infrared , Humans , Male , Female , Young Adult , Adult , Sensorimotor Cortex/physiology , Sensorimotor Cortex/diagnostic imaging , Awareness/physiology , Pleasure/physiology , Psychomotor Performance/physiology , Social Interaction , Movement/physiology , Motor Activity/physiology
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