The role of consciousness in the urge-for-action

A neuroanatomical model of urge-for-action phenomena has been proposed based on the “motivation-for-action” network (e.g., insula and mid-cingulate cortex). Notwithstanding the sound evidence presented regarding the functional and anatomical correlates of this model, the nature of the relationship between urges and conscious awareness remains to be addressed. Moreover, this model does not seem to explain (1) how a conscious access threshold is reached, and (2) the way in which the urges are related to more general contents of consciousness.Fil: Rivera Rei, Álvaro A.. Universidad Diego Portales; ChileFil: Canales Johnson, Andrés. Universidad Diego Portales; ChileFil: Huepe, David. Universidad Diego Portales; ChileFil: Ibáñez, Santiago Agustín. Universidad Diego Portales; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentin

Beyond imagination: Hypnotic visual hallucination induces greater lateralised brain activity than visual mental imagery

Hypnotic suggestions can produce a broad range of perceptual experiences, including hallucinations. Visual hypnotic hallucinations differ in many ways from regular mental images. For example, they are usually experienced as automatic, vivid, and real images, typically compromising the sense of reality. While both hypnotic hallucination and mental imagery are believed to mainly rely on the activation of the visual cortex via top-down mechanisms, it is unknown how they differ in the neural processes they engage. Here we used an adaptation paradigm to test and compare top-down processing between hypnotic hallucination, mental imagery, and visual perception in very highly hypnotisable individuals whose ability to hallucinate was assessed. By measuring the N170/VPP event-related complex and using multivariate decoding analysis, we found that hypnotic hallucination of faces involves greater top-down activation of sensory processing through lateralised neural mechanisms in the right hemisphere compared to mental imagery. Our findings suggest that the neural signatures that distinguish hypnotically hallucinated faces from imagined faces lie in the right brain hemisphere.Fil: Lanfranco, Renzo C.. University of Edinburgh; Reino Unido. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Rivera Rei, Álvaro. Universidad Adolfo Ibañez; ChileFil: Huepe, David. Universidad Adolfo Ibañez; ChileFil: Ibañez, Agustin Mariano. Universidad Adolfo Ibañez; Chile. Universidad de San Andrés. Departamento de Matemáticas y Ciencias; Argentina. University of California; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Canales Johnson, Andrés. University of Cambridge; Estados Unidos. Universidad Catolica de Maule; Chil

Alertness fluctuations when performing a task modulate cortical evoked responses to transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) has been widely used in human cognitive neuroscience to examine the causal role of distinct cortical areas in perceptual, cognitive and motor functions. However, it is widely acknowledged that the effects of focal cortical stimulation can vary substantially between participants and even from trial to trial within individuals. Recent work from resting state functional magnetic resonance imaging (fMRI) studies has suggested that spontaneous fluctuations in alertness over a testing session can modulate the neural dynamics of cortical processing, even when participants remain awake and responsive to the task at hand. Here we investigated the extent to which spontaneous fluctuations in alertness during wake-to-sleep transition can account for the variability in neurophysiological responses to TMS. We combined single-pulse TMS with neural recording via electroencephalography (EEG) to quantify changes in motor and cortical reactivity with fluctuating levels of alertness defined objectively on the basis of ongoing brain activity. We observed rapid, non-linear changes in TMS-evoked responses with decreasing levels of alertness, even while participants remained responsive in the behavioural task. Specifically, we found that the amplitude of motor evoked potentials peaked during periods of EEG flattening, whereas TMS-evoked potentials increased and remained stable during EEG flattening and the subsequent occurrence of theta ripples that indicate the onset of NREM stage 1 sleep. Our findings suggest a rapid and complex reorganization of active neural networks in response to spontaneous fluctuations of alertness over relatively short periods of behavioural testing during wake-to-sleep transition

Neurobiology of hypnosis and its contribution to the understanding of cognition and consciousness

El creciente interés por el estudio científico de la conciencia y el actual desarrollo de herramientas de neuroimagen han permitido investigar los correlatos neurobiológicos de la hipnosis y validar su utilización en el estudio de fenómenos neurocognitivos normales y patológicos. Ex-perimentalmente, se han comenzado a testear teorías que postulan que la hipnosis correspondería a un estado de conciencia neurofisiológicamente distintivo (teorías del estado), y teorías que postulan que la hipnosis sólo representaría diferente cambios neurofisiológicos asociados a sugestiones específicas, sin constituir un estado de conciencia (teorías del no estado). En este trabajo, se revisan críticamente ambas teorías, discutiendo sus características principales, describiendo la evidencia neurofisiológica asocia-da a cada teoría, y analizando el estado actual del debate entre ambas. Evidencia experimental creciente apoya la idea de que un estado de con-ciencia hipnótico involucraría principalmente regiones como la corteza cingulada anterior y la corteza frontal dorsolateral, así como un patrón de conectividad cortical funcional disminuido. Asimismo, se concluye que la sugestión hipnótica ha permitido comenzar a comprender diversos procesos neuropsicológicos normales y patológicos. Finalmente, se plantea que la evidencia neurofisiológicas actual todavía resulta insuficiente para resol-ver el debate entre teóricos del estado versus del no estado.The growing interest for the scientific study of consciousness and the current development of neuroimaging tools have allowed to investigate the neuronal correlates of hypnosis and to expand its scope to assess normal and pathological neurocognitive phenomena. At an empirical level, theories that postulate hypnosis as a neurophysiological distinctive state of consciousness (‘state theories’), and theories that claim that hypnosis would just represent different neurophysiological changes associated to specific suggestions without no change in the state of consciousness (‘non-state theories’); have both been assessed. In this work, these two theories are critically reviewed, their main features are discussed and their neurophysiological evidence is described. A growing body of evidence supports that a hypnotic state of consciousness involves mainly the anterior cingulated cortex and the dorsolateral frontal cortex; as well as a pattern of attenuated cortical functional connectivity. Also, we concluded that hypnotic suggestions have allowed a better comprehension of a diversity of normal and pathological neuropsychological processes. Finally, we stated that the neurophysiologic evidence until now is still insufficient to solve the debate between state and non-state theorists.Fil: Canales Johnson, Andrés. Universidad Diego Portales; ChileFil: Lanfranco, Renzo. Universidad Diego Portales; ChileFil: Vargas, Esteban. Pontificia Universidad Católica de Valparaíso; ChileFil: Ibañez, Agustin Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentin

Neurobiology of hypnosis and its contribution to the understanding of cognition and consciousness

El creciente interés por el estudio científico de la conciencia y el actual desarrollo de herramientas de neuroimagen han permitido investigar los correlatos neurobiológicos de la hipnosis y validar su utilización en el estudio de fenómenos neurocognitivos normales y patológicos. Ex-perimentalmente, se han comenzado a testear teorías que postulan que la hipnosis correspondería a un estado de conciencia neurofisiológicamente distintivo (teorías del estado), y teorías que postulan que la hipnosis sólo representaría diferente cambios neurofisiológicos asociados a sugestiones específicas, sin constituir un estado de conciencia (teorías del no estado). En este trabajo, se revisan críticamente ambas teorías, discutiendo sus características principales, describiendo la evidencia neurofisiológica asocia-da a cada teoría, y analizando el estado actual del debate entre ambas. Evidencia experimental creciente apoya la idea de que un estado de con-ciencia hipnótico involucraría principalmente regiones como la corteza cingulada anterior y la corteza frontal dorsolateral, así como un patrón de conectividad cortical funcional disminuido. Asimismo, se concluye que la sugestión hipnótica ha permitido comenzar a comprender diversos procesos neuropsicológicos normales y patológicos. Finalmente, se plantea que la evidencia neurofisiológicas actual todavía resulta insuficiente para resol-ver el debate entre teóricos del estado versus del no estado.The growing interest for the scientific study of consciousness and the current development of neuroimaging tools have allowed to investigate the neuronal correlates of hypnosis and to expand its scope to assess normal and pathological neurocognitive phenomena. At an empirical level, theories that postulate hypnosis as a neurophysiological distinctive state of consciousness (‘state theories’), and theories that claim that hypnosis would just represent different neurophysiological changes associated to specific suggestions without no change in the state of consciousness (‘non-state theories’); have both been assessed. In this work, these two theories are critically reviewed, their main features are discussed and their neurophysiological evidence is described. A growing body of evidence supports that a hypnotic state of consciousness involves mainly the anterior cingulated cortex and the dorsolateral frontal cortex; as well as a pattern of attenuated cortical functional connectivity. Also, we concluded that hypnotic suggestions have allowed a better comprehension of a diversity of normal and pathological neuropsychological processes. Finally, we stated that the neurophysiologic evidence until now is still insufficient to solve the debate between state and non-state theorists.Fil: Canales Johnson, Andrés. Universidad Diego Portales; ChileFil: Lanfranco, Renzo. Universidad Diego Portales; ChileFil: Vargas, Esteban. Pontificia Universidad Católica de Valparaíso; ChileFil: Ibañez, Agustin Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentin

What event-related potentials (ERPs) bring to social neuroscience?

Social cognitive neuroscience is a recent interdisciplinary field that studies the neural basis of the social mind. Event-related potentials (ERPs) provide precise information about the time dynamics of the brain. In this study, we assess the role of ERPs in cognitive neuroscience, particularly in the emerging area of social neuroscience. First, we briefly introduce the technique of ERPs. Subsequently, we describe several ERP components (P1, N1, N170, vertex positive potential, early posterior negativity, N2, P2, P3, N400, N400-like, late positive complex, late positive potential, P600, error-related negativity, feedback error-related negativity, contingent negative variation, readiness potential, lateralized readiness potential, motor potential, re-afferent potential) that assess perceptual, cognitive, and motor processing. Then, we introduce ERP studies in social neuroscience on contextual effects on speech, emotional processing, empathy, and decision making. We provide an outline of ERPs' relevance and applications in the field of social cognitive neuroscience. We also introduce important methodological issues that extend classical ERP research, such as intracranial recordings (iERP) and source location in dense arrays and simultaneous functional magnetic resonance imaging recordings. Further, this review discusses possible caveats of the ERP question assessment on neuroanatomical areas, biophysical origin, and methodological problems, and their relevance to explanatory pluralism and multilevel, contextual, and situated approaches to social neuroscience.Fil: Ibañez, Agustin Mariano. Universidad Diego Portales; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Melloni, Margherita. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Huepe, David. Universidad Diego Portales; ChileFil: Helgiu, Elena. Harvard University; Estados UnidosFil: Rivera Rei, Alvaro. Universidad Diego Portales; ChileFil: Canales Johnson, Andrés. Universidad Diego Portales; ChileFil: Baker, Phil. Universidad Favaloro; ArgentinaFil: Moya, Alvaro. Universidad Favaloro; Argentin

EEG functional connectivity metrics wPLI and wSMI account for distinct types of brain functional interactions

Abstract: The weighted Phase Lag Index (wPLI) and the weighted Symbolic Mutual Information (wSMI) represent two robust and widely used methods for MEG/EEG functional connectivity estimation. Interestingly, both methods have been shown to detect relative alterations of brain functional connectivity in conditions associated with changes in the level of consciousness, such as following severe brain injury or under anaesthesia. Despite these promising findings, it was unclear whether wPLI and wSMI may account for distinct or similar types of functional interactions. Using simulated high-density (hd-)EEG data, we demonstrate that, while wPLI has high sensitivity for couplings presenting a mixture of linear and nonlinear interdependencies, only wSMI can detect purely nonlinear interaction dynamics. Moreover, we evaluated the potential impact of these differences on real experimental data by computing wPLI and wSMI connectivity in hd-EEG recordings of 12 healthy adults during wakefulness and deep (N3-)sleep, characterised by different levels of consciousness. In line with the simulation-based findings, this analysis revealed that both methods have different sensitivity for changes in brain connectivity across the two vigilance states. Our results indicate that the conjoint use of wPLI and wSMI may represent a powerful tool to study the functional bases of consciousness in physiological and pathological conditions

Preserved sensory processing but hampered conflict detection when stimulus input is task-irrelevant

Conflict detection in sensory input is central to adaptive human behavior. Perhaps unsurprisingly, past research has shown that conflict may even be detected in the absence of conflict awareness, suggesting that conflict detection is an automatic process that does not require attention. To test the possibility of conflict processing in the absence of attention, we manipulated task relevance and response overlap of potentially conflicting stimulus features across six behavioral tasks. Multivariate analyses on human electroencephalographic data revealed neural signatures of conflict only when at least one feature of a conflicting stimulus was attended, regardless of whether that feature was part of the conflict, or overlaps with the response. In contrast, neural signatures of basic sensory processes were present even when a stimulus was completely unattended. These data reveal an attentional bottleneck at the level of objects, suggesting that object-based attention is a prerequisite for cognitive control operations involved in conflict detection

Ketamine and sleep modulate neural complexity dynamics in cats.

Funder: Programa de Desarrollo de Ciencias Básicas, PEDECIBAThere is increasing evidence that the level of consciousness can be captured by neural informational complexity: for instance, complexity, as measured by the Lempel Ziv (LZ) compression algorithm, decreases during anaesthesia and non-rapid eye movement (NREM) sleep in humans and rats, when compared with LZ in awake and REM sleep. In contrast, LZ is higher in humans under the effect of psychedelics, including subanaesthetic doses of ketamine. However, it is both unclear how this result would be modulated by varying ketamine doses, and whether it would extend to other species. Here, we studied LZ with and without auditory stimulation during wakefulness and different sleep stages in five cats implanted with intracranial electrodes, as well as under subanaesthetic doses of ketamine (5, 10, and 15 mg/kg i.m.). In line with previous results, LZ was lowest in NREM sleep, but similar in REM and wakefulness. Furthermore, we found an inverted U-shaped curve following different levels of ketamine doses in a subset of electrodes, primarily in prefrontal cortex. However, it is worth noting that the variability in the ketamine dose-response curve across cats and cortices was larger than that in the sleep-stage data, highlighting the differential local dynamics created by two different ways of modulating conscious state. These results replicate previous findings, both in humans and other species, demonstrating that neural complexity is highly sensitive to capture state changes between wake and sleep stages while adding a local cortical description. Finally, this study describes the differential effects of ketamine doses, replicating a rise in complexity for low doses, and further fall as doses approach anaesthetic levels in a differential manner depending on the cortex