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Current theories of attention differentiate exogenous from endogenous orienting of visuospatial attention. While both forms of attention orienting engage different functional systems, endogenous and exogenous attention are thought to share resources, as shown by empirical evidence of their functional interactions. The present study aims to uncover the neurobiological basis of how salient events that drive exogenous attention disrupts endogenous attention processes. We hypothesize that interference from exogenous attention over endogenous attention involves alpha-band activity, a neural marker of visuospatial attention. To test this hypothesis, we contrast the effects of endogenous attention across two experimental tasks while we recorded electroencephalography (n = 32, both sexes): a single cueing task where endogenous attention is engaged in isolation, and a double cueing task where endogenous attention is concurrently engaged with exogenous attention. Our results confirm that the concurrent engagement of exogenous attention interferes with endogenous attention processes. We also found that changes in alpha-band activity mediate the relationship between endogenous attention and its effect on task performance, and that the interference of exogenous attention on endogenous attention occurs via the moderation of this indirect effect. Altogether, our results substantiate a model of attention, whereby endogenous and exogenous attentional processes involve the same neurophysiological resources. SIGNIFICANCE STATEMENT: Scientists differentiate top-down from bottom-up visuospatial attention processes. While bottom-up attention is rapidly engaged by emerging demands from the environment, top-down attention in contrast reflects slow voluntary shifts of spatial attention. Several lines of research substantiate the idea that top-down and bottom-up attentional processes involve distinct functional systems. An increasing number of studies, however, argue that both attention systems share brain processing resources. The current study examines how salient visual events that engage bottom-up processes interfere with top-down attentional processes. Using neurophysiological recordings and multivariate pattern classification techniques, the authors show that these patterns of interference occur within the alpha-band of neural activity (8-12 Hz), which implies that bottom-up and top-down attention processes share this narrow-band frequency brain resource. The results further demonstrate that patterns of alpha-band activity explains, in part, the interference between top-down and bottom-up attention at the behavioral level.
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Encéfalo , Eletroencefalografia , Masculino , Feminino , Humanos , Encéfalo/fisiologia , Sinais (Psicologia) , Mapeamento Encefálico , Estimulação Luminosa/métodos , Tempo de Reação/fisiologiaRESUMO
Long-term genetic studies of wild populations are very scarce, but are essential for connecting ecological and population genetics models, and for understanding the dynamics of biodiversity. We present a study of a wild wheat population sampled over a 36-year period at high spatial resolution. We genotyped 832 individuals from regular sampling along transects during the course of the experiment. Genotypes were clustered into ecological microhabitats over scales of tens of metres, and this clustering was remarkably stable over the 36 generations of the study. Simulations show that it is difficult to determine whether this spatial and temporal stability reflects extremely limited dispersal or fine-scale local adaptation to ecological parameters. Using a common-garden experiment, we showed that the genotypes found in distinct microhabitats differ phenotypically. Our results provide a rare insight into the population genetics of a natural population over a long monitoring period.
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Ecossistema , Genética Populacional , Genótipo , Triticum , Triticum/genética , Fenótipo , Repetições de Microssatélites/genética , Modelos Genéticos , Variação GenéticaRESUMO
We consider theories of N-component fields with exotic spacetime symmetries, including a conserved dipole moment. Microscopic charges are immobile by symmetry, and so resemble fractons. Using collective fields we solve these models to leading order in large N. The large N solution reveals that these models are strongly correlated, and that interactions dress the microscopic charges so that they become mobile, long-lived quasiparticles. Dipole symmetry is spontaneously broken throughout the phase diagram of these models, leading to a low-energy Goldstone description.
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Recent developments in neuroscience and artificial intelligence have allowed machines to decode mental processes with growing accuracy. Neuroethicists have speculated that perfecting these technologies may result in reactions ranging from an invasion of privacy to an increase in self-understanding. Yet, evaluating these predictions is difficult given that people are poor at forecasting their reactions. To address this, we developed a paradigm using elements of performance magic to emulate future neurotechnologies. We led 59 participants to believe that a (sham) neurotechnological machine could infer their preferences, detect their errors, and reveal their deep-seated attitudes. The machine gave participants randomly assigned positive or negative feedback about their brain's supposed attitudes towards charity. Around 80% of participants in both groups provided rationalisations for this feedback, which shifted their attitudes in the manipulated direction but did not influence donation behaviour. Our paradigm reveals how people may respond to prospective neurotechnologies, which may inform neuroethical frameworks.
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Inteligência Artificial , Neurociências , Humanos , Estudos Prospectivos , Resolução de Problemas , PrevisõesRESUMO
Suggestions can cause some individuals to miss or disregard existing visual stimuli, but can they infuse sensory input with nonexistent information? Although several prominent theories of hypnotic suggestion propose that mental imagery can change our perceptual experience, data to support this stance remain sparse. The present study addressed this lacuna, showing how suggesting the presence of physically absent, yet critical, visual information transforms an otherwise difficult task into an easy one. Here, we show how adult participants who are highly susceptible to hypnotic suggestion successfully hallucinated visual occluders on top of moving objects. Our findings support the idea that, at least in some people, suggestions can add perceptual information to sensory input. This observation adds meaningful weight to theoretical, clinical, and applied aspects of the brain and psychological sciences.
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Hipnose , Adulto , Encéfalo , Humanos , SugestãoAssuntos
Alelos , Heterozigoto , Fenótipo , alfa-Globinas , Talassemia beta , Humanos , Talassemia beta/genética , alfa-Globinas/genética , Masculino , Feminino , AdultoRESUMO
Neurofeedback relying on functional magnetic resonance imaging (fMRI-nf) heralds new prospects for self-regulating brain and behavior. Here we provide the first comprehensive review of the fMRI-nf literature and the first systematic database of fMRI-nf findings. We synthesize information from 99 fMRI-nf experiments-the bulk of currently available data. The vast majority of fMRI-nf findings suggest that self-regulation of specific brain signatures seems viable; however, replication of concomitant behavioral outcomes remains sparse. To disentangle placebo influences and establish the specific effects of neurofeedback, we highlight the need for double-blind placebo-controlled studies alongside rigorous and standardized statistical analyses. Before fMRI-nf can join the clinical armamentarium, research must first confirm the sustainability, transferability, and feasibility of fMRI-nf in patients as well as in healthy individuals. Whereas modulating specific brain activity promises to mold cognition, emotion, thought, and action, reducing complex mental health issues to circumscribed brain regions may represent a tenuous goal. We can certainly change brain activity with fMRI-nf. However, it remains unclear whether such changes translate into meaningful behavioral improvements in the clinical domain.
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Mapeamento Encefálico/métodos , Imageamento por Ressonância Magnética/métodos , Neurorretroalimentação/métodos , HumanosRESUMO
BACKGROUND: Placebo and nocebo effects occur in clinical or laboratory medical contexts after administration of an inert treatment or as part of active treatments and are due to psychobiological mechanisms such as expectancies of the patient. Placebo and nocebo studies have evolved from predominantly methodological research into a far-reaching interdisciplinary field that is unravelling the neurobiological, behavioural and clinical underpinnings of these phenomena in a broad variety of medical conditions. As a consequence, there is an increasing demand from health professionals to develop expert recommendations about evidence-based and ethical use of placebo and nocebo effects for clinical practice. METHODS: A survey and interdisciplinary expert meeting by invitation was organized as part of the 1st Society for Interdisciplinary Placebo Studies (SIPS) conference in 2017. Twenty-nine internationally recognized placebo researchers participated. RESULTS: There was consensus that maximizing placebo effects and minimizing nocebo effects should lead to better treatment outcomes with fewer side effects. Experts particularly agreed on the importance of informing patients about placebo and nocebo effects and training health professionals in patient-clinician communication to maximize placebo and minimize nocebo effects. CONCLUSIONS: The current paper forms a first step towards developing evidence-based and ethical recommendations about the implications of placebo and nocebo research for medical practice, based on the current state of evidence and the consensus of experts. Future research might focus on how to implement these recommendations, including how to optimize conditions for educating patients about placebo and nocebo effects and providing training for the implementation in clinical practice.
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Consenso , Prática Clínica Baseada em Evidências , Efeito Nocebo , Efeito Placebo , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Humanos , Relações Médico-PacienteRESUMO
BACKGROUND: Bronchial challenge testing (BCT) measures airway hyperresponsiveness; asthma guidelines recommend using BCT when symptoms manifest despite normal spirometry. Improper application of these guidelines commonly results in the misdiagnosis of asthma. Yet, statistics concerning BCT remain largely obscure. The current paper addresses this gap and explores how various health variables may elucidate adherence to asthma guidelines and patterns of BCT across Canadian provinces. METHODS: Using the Access to Information Act, medical financial claims for BCT (or equivalent procedures) were requested from each of the Canadian provinces and territories. Based on the available information (from provinces only), correlations between frequency of BCT claims and medical demographics (e.g., prevalence of respirologists, health expenditures) are reported. RESULTS: Controlling for population or for people with asthma, physicians from Québec claim four times more BCT per year than those in other provinces; physicians from Alberta close to eight-fold fewer. The number of respirologists per capita and BCT per capita correlated moderately, r(132) = 0.582, p < 0.001, [95% CI 0.421, 0.716]. Excluding "outliers" (i.e., British Columbia, Alberta, and Saskatchewan) greatly strengthened this correlation, r(87) = 0.930, p < 0.001, [95% CI 0.883, 0.958]. DISCUSSION: These findings demonstrate that provinces vary in their use of BCT. This result seems to stem, at least in part, from differences in the prevalence of respirologists. Interestingly, geographic region appears to wield a strong influence; in the correlation between number of tests and number of respirologists, physicians from Western provinces (i.e., Alberta, Saskatchewan, and British Columbia) administered fewer tests than their Eastern colleagues. Given the association between inadequate application of BCT and misdiagnosis of asthma, physicians should pay special attention to the Canadian guidelines when considering an asthma diagnosis.
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Cognitive neuroscientists rarely consider the influence that body position exerts on brain activity; yet, postural variation holds important implications for the acquisition and interpretation of neuroimaging data. Whereas participants in most behavioral and EEG experiments sit upright, many prominent brain imaging techniques (e.g., fMRI) require participants to lie supine. Here we demonstrate that physical comportment profoundly alters baseline brain activity as measured by magnetoencephalography (MEG)-an imaging modality that permits multipostural acquisition. We collected resting-state MEG data from 12 healthy participants in three postures (lying supine, reclining at 45°, and sitting upright). Source-modeling analysis revealed a broadly distributed influence of posture on resting brain function. Sitting upright versus lying supine was associated with greater high-frequency (i.e., beta and gamma) activity in widespread parieto-occipital cortex. Moreover, sitting upright and reclining postures correlated with dampened activity in prefrontal regions across a range of bandwidths (i.e., from alpha to low gamma). The observed effects were large, with a mean Cohen's d of 0.95 ( SD = 0.23). In addition to neural activity, physiological parameters such as muscle tension and eye blinks may have contributed to these posture-dependent changes in brain signal. Regardless of the underlying mechanisms, however, the present results have important implications for the acquisition and interpretation of multimodal imaging data (e.g., studies combining fMRI or PET with EEG or MEG). More broadly, our findings indicate that generalizing results-from supine neuroimaging measurements to erect positions typical of ecological human behavior-would call for considering the influence that posture wields on brain dynamics.
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Encéfalo/fisiologia , Magnetoencefalografia , Postura/fisiologia , Adulto , Mapeamento Encefálico , Ondas Encefálicas/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , DescansoRESUMO
In order to study the feeling of control over decisions, we told 60 participants that a neuroimaging machine could read and influence their thoughts. While inside a mock brain scanner, participants chose arbitrary numbers in two similar tasks. In the Mind-Reading Task, the scanner appeared to guess the participants' numbers; in the Mind-Influencing Task, it appeared to influence their choice of numbers. We predicted that participants would feel less voluntary control over their decisions when they believed that the scanner was influencing their choices. As predicted, participants felt less control and made slower decisions in the Mind-Influencing Task compared to the Mind-Reading Task. A second study replicated these findings. Participants' experience of the ostensible influence varied, with some reporting an unknown source directing them towards specific numbers. This simulated thought insertion paradigm can therefore influence feelings of voluntary control and may help model symptoms of mental disorders.
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Cognição/fisiologia , Enganação , Tomada de Decisões/fisiologia , Emoções/fisiologia , Julgamento/fisiologia , Magia/psicologia , Adulto , Feminino , Humanos , Estudantes/psicologia , Universidades , Adulto JovemRESUMO
Neurofeedback draws on multiple techniques that propel both healthy and patient populations to self-regulate neural activity. Since the 1970s, numerous accounts have promoted electroencephalography-neurofeedback as a viable treatment for a host of mental disorders. Today, while the number of health care providers referring patients to neurofeedback practitioners increases steadily, substantial methodological and conceptual caveats continue to pervade empirical reports. And yet, nascent imaging technologies (e.g., real-time functional magnetic resonance imaging) and increasingly rigorous protocols are paving the road towards more effective applications and a better scientific understanding of the underlying mechanisms. Here, we outline common neurofeedback methods, illuminate the tenuous state of the evidence, and sketch out future directions to further unravel the potential merits of this contentious therapeutic prospect.
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Mapeamento Encefálico/métodos , Eletroencefalografia , Transtornos Mentais/terapia , Neurorretroalimentação/métodos , Autocontrole , Encéfalo/fisiologia , Encéfalo/fisiopatologia , Estudos Clínicos como Assunto , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Transtornos Mentais/fisiopatologiaRESUMO
Forcing occurs when a magician influences the audience's decisions without their awareness. To investigate the mechanisms behind this effect, we examined several stimulus and personality predictors. In Study 1, a magician flipped through a deck of playing cards while participants were asked to choose one. Although the magician could influence the choice almost every time (98%), relatively few (9%) noticed this influence. In Study 2, participants observed rapid series of cards on a computer, with one target card shown longer than the rest. We expected people would tend to choose this card without noticing that it was shown longest. Both stimulus and personality factors predicted the choice of card, depending on whether the influence was noticed. These results show that combining real-world and laboratory research can be a powerful way to study magic and can provide new methods to study the feeling of free will.
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Conscientização/fisiologia , Comportamento de Escolha/fisiologia , Magia/psicologia , Personalidade/fisiologia , Volição/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto JovemRESUMO
This article examines a large cohort of previously suicidal adolescents, identifying those that surpassed threshold criteria for borderline personality disorder (BPD), according to the Abbreviated Diagnostic Interview of Borderlines (Ab-DIB), and determining the stability, correlates and predictors of BPD from early-to-late adolescence. Two hundred and eighty-six youth (mean baseline age 14.6 years; SD 1.5), presenting consecutively to a metropolitan pediatric hospital emergency department for evaluation of suicidality, were assessed at initial consultation for Axis I and II disorders and demographic and clinical variables. Two hundred and twenty-nine (80%) were re-assessed for those variables 4 years later and 204 (70.3%) had complete data sets at recruitment and follow-up. Previously suicidal youths who met BPD threshold on the Ab-DIB at recruitment were distinguishable at baseline from those who did not in conduct disorder symptoms (p < 0.003), lower levels of functioning (p < 0.001), drug use (p < 0.001), stressful life events (p < 0.003) and family relations (p < 0.001). The BPD diagnosis was consistent, according to this measure, at baseline and follow-up for 76% of participants. Four groups with respect to borderline pathology (persisting, remitting, emerging and never) were identified (ICC = 0.603, 95% CI = 0.40-0.78). Persistent BPD status was predictable by older age at presentation (p < 0.01) and level of functioning (p < 0.05). Eight percent were also suicidal at the 4-year follow-up. Using a self-report measure of BPD, we suggest that suicidal youth can indeed be diagnosed with the disorder at 14 years old, supporting the shift from DSM-IV to DSM-5, given what appears to be its temporal stability, differentiation of those suffering with considerable symptomatology or not, and predictors of its status in late adolescence. The low suicidality rate at follow-up indicates a good short-term prognosis.
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Transtorno da Personalidade Borderline/diagnóstico , Transtorno da Personalidade Borderline/psicologia , Ideação Suicida , Suicídio/psicologia , Adolescente , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Seguimentos , Humanos , Masculino , Índice de Gravidade de Doença , Transtornos Relacionados ao Uso de SubstânciasRESUMO
Over more than two decades, studies using imaging techniques of the living human brain have begun to explore the neural correlates of hypnosis. The collective findings provide a gripping, albeit preliminary, account of the underlying neurobiological mechanisms involved in hypnotic phenomena. While substantial advances lend support to different hypotheses pertaining to hypnotic modulation of attention, control, and monitoring processes, the complex interactions among the many mediating variables largely hinder our ability to isolate robust commonalities across studies. The present account presents a critical integrative synthesis of neuroimaging studies targeting hypnosis as a function of suggestion. Specifically, hypnotic induction without task-specific suggestion is examined, as well as suggestions concerning sensation and perception, memory, and ideomotor response. The importance of carefully designed experiments is highlighted to better tease apart the neural correlates that subserve hypnotic phenomena. Moreover, converging findings intimate that hypnotic suggestions seem to induce specific neural patterns. These observations propose that suggestions may have the ability to target focal brain networks. Drawing on evidence spanning several technological modalities, neuroimaging studies of hypnosis pave the road to a more scientific understanding of a dramatic, yet largely evasive, domain of human behavior.
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Encéfalo/fisiologia , Neuroimagem Funcional , Hipnose , HumanosRESUMO
Hypnotic suggestibility--loosely termed hypnotizability--is difficult to assess across cultures. Investigators often use translated research instruments to guide their inquiry in disparate geographic locations. Present-day hypnosis researchers rely heavily on two primary scales that are more than half a century old: the Stanford Hypnotic Susceptibility Scale: Form C (SHSS:C) (Weitzenhoffer & Hilgard, 1959) and the Harvard Group Scale of Hypnotic Susceptibility: Form A (HGSHS:A) (Shor & Orne, 1962). Scholars typically translate these scales to measure hypnotizability transculturally. This approach, however, operates under the specious assumption that the concept of hypnotizability is largely monolithic or universal across cultures. Whereas translations likely conserve the linguistic content, they may arguably imply different cultural meanings and historical subtexts. Whereas social scientists acknowledge the importance of qualitative and phenomenological accounts in the study of altered consciousness, including suggestibility, researchers interested in hypnotizability consider the impact of findings from anthropology and ethnography too little. Clinicians and scholars of hypnosis would stand to benefit from incorporating the insights afforded by transcultural research in the overarching investigation of a concept as nuanced as hypnotizability.
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Comparação Transcultural , Hipnose/métodos , Testes Psicológicos , Sugestão , Antropologia Cultural , Humanos , Tradução , Resultado do TratamentoRESUMO
Cognitive scientists routinely distinguish between controlled and automatic mental processes. Through learning, practice, and exposure, controlled processes can become automatic; however, whether automatic processes can become deautomatized - recuperated under the purview of control - remains unclear. Here we show that a suggestion derails a deeply ingrained process involving involuntary audiovisual integration. We compared the performance of highly versus less hypnotically suggestible individuals (HSIs versus LSIs) in a classic McGurk paradigm - a perceptual illusion task demonstrating the influence of visual facial movements on auditory speech percepts. Following a posthypnotic suggestion to prioritize auditory input, HSIs but not LSIs manifested fewer illusory auditory perceptions and correctly identified more auditory percepts. Our findings demonstrate that a suggestion deautomatized a ballistic audiovisual process in HSIs. In addition to guiding our knowledge regarding theories and mechanisms of automaticity, the present findings pave the road to a more scientific understanding of top-down effects and multisensory integration.
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Atenção/fisiologia , Ilusões/fisiologia , Percepção da Fala/fisiologia , Sugestão , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Distribuição AleatóriaRESUMO
When it comes to antidepressant medications - popular, backbone drugs of modern psychiatry - even learned scholars and savvy clinicians find it difficult to separate honest, rigorous research from that which thrives on hidden agendas and ulterior motives. Fortunately, a mounting corpus of data-based studies, mostly meta-analyses, casts new and critical light on the clinical efficacy, side effects, and therapeutic outcomes of antidepressants. Spearheading these efforts over the past few decades, Irving Kirsch and colleagues have challenged the hegemonic view of antidepressants as an effective therapeutic intervention. Notably, Kirsch illuminates the small difference between antidepressants and placebos in mitigating depression-a difference that may be statistically significant yet fails to reach clinical significance. This piece sketches the important contributions Kirsch has made to the scientific understanding of antidepressant medications.