brainlife.io: a decentralized and open-source cloud platform to support neuroscience research.

Neuroscience is advancing standardization and tool development to support rigor and transparency. Consequently, data pipeline complexity has increased, hindering FAIR (findable, accessible, interoperable and reusable) access. brainlife.io was developed to democratize neuroimaging research. The platform provides data standardization, management, visualization and processing and automatically tracks the provenance history of thousands of data objects. Here, brainlife.io is described and evaluated for validity, reliability, reproducibility, replicability and scientific utility using four data modalities and 3,200 participants.

Further characterisation of late somatosensory evoked potentials using electroencephalogram and magnetoencephalogram source imaging.

Beside the well-documented involvement of secondary somatosensory area, the cortical network underlying late somatosensory evoked potentials (P60/N60 and P100/N100) is still unknown. Electroencephalogram and magnetoencephalogram source imaging were performed to further investigate the origin of the brain cortical areas involved in late somatosensory evoked potentials, using sensory inputs of different strengths and by testing the correlation between cortical sources. Simultaneous high-density electroencephalograms and magnetoencephalograms were performed in 19 participants, and electrical stimulation was applied to the median nerve (wrist level) at intensity between 1.5 and 9 times the perceptual threshold. Source imaging was undertaken to map the stimulus-induced brain cortical activity according to each individual brain magnetic resonance imaging, during three windows of analysis covering early and late somatosensory evoked potentials. Results for P60/N60 and P100/N100 were compared with those for P20/N20 (early response). According to literature, maximal activity during P20/N20 was found in central sulcus contralateral to stimulation site. During P60/N60 and P100/N100, activity was observed in contralateral primary sensorimotor area, secondary somatosensory area (on both hemispheres) and premotor and multisensory associative cortices. Late responses exhibited similar characteristics but different from P20/N20, and no significant correlation was found between early and late generated activities. Specific clusters of cortical activities were activated with specific input/output relationships underlying early and late somatosensory evoked potentials. Cortical networks, partly common to and distinct from early somatosensory responses, contribute to late responses, all participating in the complex somatosensory brain processing.

Time course of EEG power during creative problem-solving with insight or remote thinking.

Problem-solving often requires creativity and is critical in everyday life. However, the neurocognitive mechanisms underlying creative problem-solving remain poorly understood. Two mechanisms have been highlighted: the formation of new connections among problem elements and insight solving, characterized by sudden realization of a solution. In this study, we investigated EEG activity during a modified version of the remote associates test, a classical insight problem task that requires finding a word connecting three unrelated words. This allowed us to explore the brain correlates associated with the semantic remoteness of connections (by varying the remoteness of the solution word across trials) and with insight solving (identified as a Eurêka moment reported by the participants). Semantic remoteness was associated with power increase in the alpha band (8-12 Hz) in a left parieto-temporal cluster, the beta band (13-30 Hz) in a right fronto-temporal cluster in the early phase of the task, and the theta band (3-7 Hz) in a bilateral frontal cluster just prior to participants' responses. Insight solving was associated with power increase preceding participants' responses in the alpha and gamma (31-60 Hz) bands in a left temporal cluster and the theta band in a frontal cluster. Source reconstructions revealed the brain regions associated with these clusters. Overall, our findings shed new light on some of the mechanisms involved in creative problem-solving.

A brain atlas of axonal and synaptic delays based on modelling of cortico-cortical evoked potentials.

Epilepsy presurgical investigation may include focal intracortical single-pulse electrical stimulations with depth electrodes, which induce cortico-cortical evoked potentials at distant sites because of white matter connectivity. Cortico-cortical evoked potentials provide a unique window on functional brain networks because they contain sufficient information to infer dynamical properties of large-scale brain connectivity, such as preferred directionality and propagation latencies. Here, we developed a biologically informed modelling approach to estimate the neural physiological parameters of brain functional networks from the cortico-cortical evoked potentials recorded in a large multicentric database. Specifically, we considered each cortico-cortical evoked potential as the output of a transient stimulus entering the stimulated region, which directly propagated to the recording region. Both regions were modelled as coupled neural mass models, the parameters of which were estimated from the first cortico-cortical evoked potential component, occurring before 80 ms, using dynamic causal modelling and Bayesian model inversion. This methodology was applied to the data of 780 patients with epilepsy from the F-TRACT database, providing a total of 34 354 bipolar stimulations and 774 445 cortico-cortical evoked potentials. The cortical mapping of the local excitatory and inhibitory synaptic time constants and of the axonal conduction delays between cortical regions was obtained at the population level using anatomy-based averaging procedures, based on the Lausanne2008 and the HCP-MMP1 parcellation schemes, containing 130 and 360 parcels, respectively. To rule out brain maturation effects, a separate analysis was performed for older (>15 years) and younger patients (<15 years). In the group of older subjects, we found that the cortico-cortical axonal conduction delays between parcels were globally short (median = 10.2 ms) and only 16% were larger than 20 ms. This was associated to a median velocity of 3.9 m/s. Although a general lengthening of these delays with the distance between the stimulating and recording contacts was observed across the cortex, some regions were less affected by this rule, such as the insula for which almost all efferent and afferent connections were faster than 10 ms. Synaptic time constants were found to be shorter in the sensorimotor, medial occipital and latero-temporal regions, than in other cortical areas. Finally, we found that axonal conduction delays were significantly larger in the group of subjects younger than 15 years, which corroborates that brain maturation increases the speed of brain dynamics. To our knowledge, this study is the first to provide a local estimation of axonal conduction delays and synaptic time constants across the whole human cortex in vivo, based on intracerebral electrophysiological recordings.

Statistical power: Implications for planning MEG studies.

Statistical power is key for robust, replicable science. Here, we systematically explored how numbers of trials and subjects affect statistical power in MEG sensor-level data. More specifically, we simulated "experiments" using the MEG resting-state dataset of the Human Connectome Project (HCP). We divided the data in two conditions, injected a dipolar source at a known anatomical location in the "signal condition", but not in the "noise condition", and detected significant differences at sensor level with classical paired t-tests across subjects, using amplitude, squared amplitude, and global field power (GFP) measures. Group-level detectability of these simulated effects varied drastically with anatomical origin. We thus examined in detail which spatial properties of the sources affected detectability, looking specifically at the distance from closest sensor and orientation of the source, and at the variability of these parameters across subjects. In line with previous single-subject studies, we found that the most detectable effects originate from source locations that are closest to the sensors and oriented tangentially with respect to the head surface. In addition, cross-subject variability in orientation also affected group-level detectability, boosting detection in regions where this variability was small and hindering detection in regions where it was large. Incidentally, we observed a considerable covariation of source position, orientation, and their cross-subject variability in individual brain anatomical space, making it difficult to assess the impact of each of these variables independently of one another. We thus also performed simulations where we controlled spatial properties independently of individual anatomy. These additional simulations confirmed the strong impact of distance and orientation and further showed that orientation variability across subjects affects detectability, whereas position variability does not. Importantly, our study indicates that strict unequivocal recommendations as to the ideal number of trials and subjects for any experiment cannot be realistically provided for neurophysiological studies and should be adapted according to the brain regions under study.

Functional disconnection of associative cortical areas predicts performance during BCI training.

Brain-computer interfaces (BCIs) have been largely developed to allow communication, control, and neurofeedback in human beings. Despite their great potential, BCIs perform inconsistently across individuals and the neural processes that enable humans to achieve good control remain poorly understood. To address this question, we performed simultaneous high-density electroencephalographic (EEG) and magnetoencephalographic (MEG) recordings in a motor imagery-based BCI training involving a group of healthy subjects. After reconstructing the signals at the cortical level, we showed that the reinforcement of motor-related activity during the BCI skill acquisition is paralleled by a progressive disconnection of associative areas which were not directly targeted during the experiments. Notably, these network connectivity changes reflected growing automaticity associated with BCI performance and predicted future learning rate. Altogether, our findings provide new insights into the large-scale cortical organizational mechanisms underlying BCI learning, which have implications for the improvement of this technology in a broad range of real-life applications.

The impact of eye contact on the sense of agency.

Recent research suggests that eye contact can lead to enhanced self-awareness. A related phenomenon, the sense of agency deals with the notion of the self as the origin of our actions. Possible links between eye contact and agency have been so far neglected. Here, we investigated whether an implicit sense of agency could be modulated by eye gaze. We asked participants to respond (button press) to a face stimulus: looking or not at the participant (experiment 1); or displaying distinct eye gaze before or after a mask (experiment 2). After each trial, participants estimated the time between their key press and the ensuing effects. We found enhanced intentional binding for conditions that involved direct compared to averted gaze. This study supports the idea that eye contact is an important cue that affects complex cognitive processes and suggests that modulating self-processing can impact the sense of agency.

Comparison of two integration methods for dynamic causal modeling of electrophysiological data.

Dynamic causal modeling (DCM) is a methodological approach to study effective connectivity among brain regions. Based on a set of observations and a biophysical model of brain interactions, DCM uses a Bayesian framework to estimate the posterior distribution of the free parameters of the model (e.g. modulation of connectivity) and infer architectural properties of the most plausible model (i.e. model selection). When modeling electrophysiological event-related responses, the estimation of the model relies on the integration of the system of delay differential equations (DDEs) that describe the dynamics of the system. In this technical note, we compared two numerical schemes for the integration of DDEs. The first, and standard, scheme approximates the DDEs (more precisely, the state of the system, with respect to conduction delays among brain regions) using ordinary differential equations (ODEs) and solves it with a fixed step size. The second scheme uses a dedicated DDEs solver with adaptive step sizes to control error, making it theoretically more accurate. To highlight the effects of the approximation used by the first integration scheme in regard to parameter estimation and Bayesian model selection, we performed simulations of local field potentials using first, a simple model comprising 2 regions and second, a more complex model comprising 6 regions. In these simulations, the second integration scheme served as the standard to which the first one was compared. Then, the performances of the two integration schemes were directly compared by fitting a public mismatch negativity EEG dataset with different models. The simulations revealed that the use of the standard DCM integration scheme was acceptable for Bayesian model selection but underestimated the connectivity parameters and did not allow an accurate estimation of conduction delays. Fitting to empirical data showed that the models systematically obtained an increased accuracy when using the second integration scheme. We conclude that inference on connectivity strength and delay based on DCM for EEG/MEG requires an accurate integration scheme.

Postsurgical Disfigurement Influences Disgust Recognition: A Case-Control Study.

BACKGROUND: Little is known about how emotion recognition may be modified in individuals prone to elicit disgust. OBJECTIVE: We sought to determine if subjects with total laryngectomy would present a modified recognition of facial expressions of disgust. METHODS: A total of 29 patients presenting with a history of advanced-stage laryngeal cancer were recruited, 17 being surgically treated (total laryngectomy) and 12 treated with chemoradiation therapy only. Based on a validated set of images of facial expressions of fear, disgust, surprise, happiness, sadness and anger displayed by 6 actors, we presented participants with expressions of each emotion at 5 levels of increasing intensity and measured their ability to recognize these emotions. RESULTS: Participants with (vs without) laryngectomy showed a higher threshold for the recognition of disgust (3.2. vs 2.7 images needed before emotion recognition, p = 0.03) and a lower success rate of correct recognition (75.5% vs 88.9%, p = 0.03). CONCLUSION: Subjects presenting with an aesthetic impairment of the head and neck showed poorer performance in disgust recognition when compared with those without disfigurement. These findings might relate either to some perceptual adaptation, habituation phenomenon, or to some higher-level processes related to emotion regulation strategies.

An Intracranial EEG Study of the Neural Dynamics of Musical Valence Processing.

The processing of valence is known to recruit the amygdala, orbitofrontal cortex, and relevant sensory areas. However, how these regions interact remains unclear. We recorded cortical electrical activity from 7 epileptic patients implanted with depth electrodes for presurgical evaluation while they listened to positively and negatively valenced musical chords. Time-frequency analysis suggested a specific role of the orbitofrontal cortex in the processing of positively valenced stimuli while, most importantly, Granger causality analysis revealed that the amygdala tends to drive both the orbitofrontal cortex and the auditory cortex in theta and alpha frequency bands, during the processing of valenced stimuli. Results from the current study show the amygdala to be a critical hub in the emotion processing network: specifically one that influences not only the higher order areas involved in the evaluation of a stimulus's emotional value but also the sensory cortical areas involved in the processing of its low-level acoustic features.

Watching Eyes effects: When others meet the self.

The perception of direct gaze-that is, of another individual's gaze directed at the observer-is known to influence a wide range of cognitive processes and behaviors. We present a new theoretical proposal to provide a unified account of these effects. We argue that direct gaze first captures the beholder's attention and then triggers self-referential processing, i.e., a heightened processing of stimuli in relation with the self. Self-referential processing modulates incoming information processing and leads to the Watching Eyes effects, which we classify into four main categories: the enhancement of self-awareness, memory effects, the activation of pro-social behavior, and positive appraisals of others. We advance that the belief to be the object of another's attention is embedded in direct gaze perception and gives direct gaze its self-referential power. Finally, we stress that the Watching Eyes effects reflect a positive impact on human cognition; therefore, they may have a therapeutic potential, which future research should delineate.

Different patterns of recollection impairment in confabulation reveal different disorders of consciousness: A multiple case study.

Recollection is used to refer to the active process of setting up retrieval cues, evaluating the outcome, and systematically working toward a representation of a past experience that we find acceptable. In this study we report on three patients showing different patterns of confabulation affecting recollection and consciousness differentially. All patients confabulated in the episodic past domain. However, whereas in one patient confabulation affected only recollection of events concerning his personal past, present and future, in another patient confabulation also affected recollection of impersonal knowledge. The third patient showed an intermediate pattern of confabulation, which affected selectively the retrieval of past information, both personal and impersonal. We suggest that our results are in favor of a fractionation of processes involved in recollection underling different disorders of consciousness.

Only your eyes tell me what you like: Exploring the liking effect induced by other's gaze.

Our preferences are sensitive to social influences. For instance, we like more the objects that are looked-at by others than non-looked-at objects. Here, we explored this liking effect, using a modified paradigm of attention cueing by gaze. First, we investigated if the liking effect induced by gaze relied on motoric representations of the target object by testing if the liking effect could be observed for non-manipulable (alphanumeric characters) as well as for manipulable items (common tools). We found a significant liking effect for the alphanumeric items. Second, we tested if another type of powerful social cue could also induce a liking effect. We used an equivalent paradigm but with pointing hands instead of gaze cues. Pointing hands elicited a robust attention-orienting effect, but they did not induce any significant liking effect. This study extends previous findings and reinforces the view of eye gaze as a special cue in human interactions.

The Memory Binding Test Detects Early Subtle Episodic Memory Decline in Preclinical Alzheimer's Disease: A Longitudinal Study.

Background: The asymptomatic at-risk phase might be the optimal time-window to establish clinically meaningful endpoints in Alzheimer's disease (AD). Objective: We investigated whether, compared with the Free and Cued Selective Reminding Test (FCSRT), the Memory Binding Test (MBT) can anticipate the diagnosis of emergent subtle episodic memory (EM) deficits to an at-risk phase. Methods: Five-year longitudinal FCSRT and MBT scores from 45 individuals matched for age, education, and gender, were divided into 3 groups of 15 subjects: Aß-/controls, Aß+/stable, and Aß+/progressors (preclinical-AD). The MBT adds an associative memory component (binding), particularly sensitive to subtle EM decline. Results: In the MBT, EM decline started in the Aß+/progressors (preclinical-AD) up to 4 years prior to diagnosis in delayed free recall (FR), followed by decline in binding-associated scores 1 year later. Conversely, in the FCSRT, EM-decline began later, up to 3 years prior to diagnosis, in the same group on both immediate and delayed versions of FR, while on total recall (TR) and intrusions decline started only 1 year prior to diagnosis. Conclusions: The MBT seems more sensitive than the FCSRT for early EM-decline detection, regarding the year of diagnosis and the number of scores showing AD-linked EM deficits (associated with the AD-characteristic amnesic hippocampal syndrome). Considering the MBT as a detection tool of early subtle EM-decline in an asymptomatic at-risk phase, and the FCSRT as a classification tool of stages of EM-decline from a preclinical phase, these tests ought to potentially become complementary diagnostic tools that can foster therapies to delay cognitive decline. Clinical trial registration title: Electrophysiological markers of the progression to clinical Alzheimer disease in asymptomatic at-risk individuals: a longitudinal event-related potential study of episodic memory in the INSIGHT pre-AD cohort (acronym: ePARAD).

Measuring neuronal avalanches to inform brain-computer interfaces.

Large-scale interactions among multiple brain regions manifest as bursts of activations called neuronal avalanches, which reconfigure according to the task at hand and, hence, might constitute natural candidates to design brain-computer interfaces (BCIs). To test this hypothesis, we used source-reconstructed magneto/electroencephalography during resting state and a motor imagery task performed within a BCI protocol. To track the probability that an avalanche would spread across any two regions, we built an avalanche transition matrix (ATM) and demonstrated that the edges whose transition probabilities significantly differed between conditions hinged selectively on premotor regions in all subjects. Furthermore, we showed that the topology of the ATMs allows task-decoding above the current gold standard. Hence, our results suggest that neuronal avalanches might capture interpretable differences between tasks that can be used to inform brain-computer interfaces.

Altering experienced utility by incidental affect: The interplay of valence and arousal in incidental affect infusion processes.

The way we evaluate an experience can be influenced by contextual factors that are unrelated to the experience at hand. A prominent factor that has been shown to infuse into the evaluation processes is incidental affect. Prior research has examined the role of such incidental affect by either focusing on its valence or its arousal, while neglecting the interplay of these two components in the affect infusion process. Based on the affect-integration-motivation (AIM) framework from affective neuroscience, our research proposes a novel arousal transport hypothesis (ATH) that describes how valence and arousal of an affective state jointly influence the evaluation of experiences. We test the ATH in a set of multimethod studies combining functional magnetic resonance imaging (fMRI), skin conductance recording, automated facial affect recording, and behavioral approaches across a range of sensory modalities including auditory, gustatory, and visual. We find that positive incidental affect, induced by viewing affect-laden pictures (vs. neutral pictures) or winning (vs. not winning) monetary rewards, enhances how much an experience (i.e., listening to music, consuming wines, or looking at images) is enjoyed. Tracking moment-based changes of affective states at the neurophysiological level, we demonstrate that valence mediates reported enjoyment and that arousal is necessary to implement and moderate these mediating effects. We rule out alternative explanations for these mediation patterns such as the excitation transfer account and the attention narrowing account. Finally, we discuss how the ATH framework provides a new perspective to explain divergent decision outcomes caused by discrete emotions and its implications for effort-based decision-making. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Can a failure in the error-monitoring system explain unawareness of memory deficits in Alzheimer's disease?

Unawareness of memory deficits is an early manifestation in patients with Alzheimer's disease (AD), which often delays diagnosis. This intriguing behavior constitutes a form of anosognosia, whose neural mechanisms remain largely unknown. We hypothesized that anosognosia may depend on a critical synaptic failure in the error-monitoring system, which would prevent AD patients from being aware of their own memory impairment. To investigate, we measured event-related potentials (ERPs) evoked by erroneous responses during a word memory recognition task in two groups of amyloid positive individuals with only subjective memory complaints at study entry: those who progressed to AD within the five-year study period (PROG group), and those who remained cognitively normal (CTRL group). A significant reduction in the amplitude of the positivity error (Pe), an ERP related to error awareness, was observed in the PROG group at the time of AD diagnosis (vs study entry) in intra-group analysis, as well as when compared with the CTRL group in inter-group analysis, based on the last EEG acquisition for all subjects. Importantly, at the time of AD diagnosis, the PROG group exhibited clinical signs of anosognosia, overestimating their cognitive abilities, as evidenced by the discrepancy scores obtained from caregiver/informant vs participant reports on the cognitive subscale of the Healthy Aging Brain Care Monitor. To our knowledge, this is the first study to reveal the emergence of a failure in the error-monitoring system during a word memory recognition task at the early stages of AD. This finding, along with the decline of awareness for cognitive impairment observed in the PROG group, strongly suggests that a synaptic dysfunction in the error-monitoring system may be the critical neural mechanism at the origin of unawareness of deficits in AD.

Very early modulation of brain responses to neutral faces by a single prior association with an emotional context: evidence from MEG.

Recent electrophysiological studies have demonstrated modulations of the very first stages of visual processing (<100 ms) due to prior experience. This indicates an influence of a memory trace on the earliest stages of stimulus processing. Here we investigated if emotional audio-verbal information associated with faces on first encounter can affect the very early responses to those faces on subsequent exposure. We recorded magneto-encephalographic (MEG) responses to neutral faces that had been previously associated with positive (happy), negative (angry) or neutral auditory verbal emotional contexts. Our results revealed a very early (30-60 ms) difference in the brain responses to the neutral faces according to the type of previously associated emotional context, with a clear dissociation between the faces previously associated to positive vs. negative or neutral contexts. Source localization showed that two main regions were involved in this very early association effect: the bilateral ventral occipito-temporal regions and the right anterior medial temporal region. These results provide evidence that the memory trace of a face integrates positive emotional cues present in the context of prior encounter and that this emotional memory can influence the very first stages of face processing. These experimental findings support the idea that face perception can be shaped by experience from its earliest stages and in particular through emotional association effects.

Behavioural and magnetoencephalographic evidence for the interaction between semantic and episodic memory in healthy elderly subjects.

The relationship between episodic and semantic memory systems has long been debated. Some authors argue that episodic memory is contingent on semantic memory (Tulving 1984), while others postulate that both systems are independent since they can be selectively damaged (Squire 1987). The interaction between these memory systems is particularly important in the elderly, since the dissociation of episodic and semantic memory defects characterize different aging-related pathologies. Here, we investigated the interaction between semantic knowledge and episodic memory processes associated with faces in elderly subjects using an experimental paradigm where the semantic encoding of famous and unknown faces was compared to their episodic recognition. Results showed that the level of semantic awareness of items affected the recognition of those items in the episodic memory task. Event-related magnetic fields confirmed this interaction between episodic and semantic memory: ERFs related to the old/new effect during the episodic task were markedly different for famous and unknown faces. The old/new effect for famous faces involved sustained activities maximal over right temporal sensors, showing a spatio-temporal pattern partly similar to that found for famous versus unknown faces during the semantic task. By contrast, an old/new effect for unknown faces was observed on left parieto-occipital sensors. These findings suggest that the episodic memory for famous faces activated the retrieval of stored semantic information, whereas it was based on items' perceptual features for unknown faces. Overall, our results show that semantic information interfered markedly with episodic memory processes and suggested that the neural substrates of these two memory systems overlap.