4,323 research outputs found
Schizophrenia – time to commit to policy change
Schizophrenia is recognised as one of the most complex and profound mental health conditions, steeped in both myth and reality. Efforts needs to be multifaceted, including policy development, treatment guidance and scientific innovation, with all stakeholders working together to ensure meaningful progress. This report delves into the unique needs of people with schizophrenia, exploring supportive measures for their well-being, practical and attainable recommendations for change. The message to all nations, policy makers, payers and healthcare professionals is clear: strive for excellence, but most importantly – start somewhere
Lyapunov exponents and extensivity of strongly coupled chaotic maps in regular graphs
Acknowledgements J.G. acknowledges funds from the Agencia Nacional de InvestigaciĂłn e In nonvaciĂłn (ANII), Uruguay, POS_NAC_2018_1_151185, and the ComisiĂłn Academica de Posgrado (CAP), Universidad de la RepĂşblica, Uruguay. Both authors acknowledge funds from the ComisiĂłn Sectorial de InvestigaciĂłn Ci475 entifĂca (CSIC), Uruguay, group grant “CSIC2018 - FID13 - grupo ID 722”.Peer reviewedPublisher PD
Insights into oscillator network dynamics using a phase-isostable framework
Networks of coupled nonlinear oscillators can display a wide range of emergent behaviors under the variation of the strength of the coupling. Network equations for pairs of coupled oscillators where the dynamics of each node is described by the evolution of its phase and slowest decaying isostable coordinate have previously been shown to capture bifurcations and dynamics of the network, which cannot be explained through standard phase reduction. An alternative framework using isostable coordinates to obtain higher-order phase reductions has also demonstrated a similar descriptive ability for two oscillators. In this work, we consider the phase-isostable network equations for an arbitrary but finite number of identical coupled oscillators, obtaining conditions required for the stability of phase-locked states including synchrony. For the mean-field complex Ginzburg–Landau equation where the solutions of the full system are known, we compare the accuracy of the phase-isostable network equations and higher-order phase reductions in capturing bifurcations of phase-locked states. We find the former to be the more accurate and, therefore, employ this to investigate the dynamics of globally linearly coupled networks of Morris–Lecar neuron models (both two and many nodes). We observe qualitative correspondence between results from numerical simulations of the full system and the phase-isostable description demonstrating that in both small and large networks, the phase-isostable framework is able to capture dynamics that the first-order phase description cannot
Resting-state EEG signatures of Alzheimer's disease are driven by periodic but not aperiodic changes
Electroencephalography (EEG) has shown potential for identifying early-stage biomarkers of neurocognitive dysfunction associated with dementia due to Alzheimer's disease (AD). A large body of evidence shows that, compared to healthy controls (HC), AD is associated with power increases in lower EEG frequencies (delta and theta) and decreases in higher frequencies (alpha and beta), together with slowing of the peak alpha frequency. However, the pathophysiological processes underlying these changes remain unclear. For instance, recent studies have shown that apparent shifts in EEG power from high to low frequencies can be driven either by frequency specific periodic power changes or rather by non-oscillatory (aperiodic) changes in the underlying 1/f slope of the power spectrum. Hence, to clarify the mechanism(s) underlying the EEG alterations associated with AD, it is necessary to account for both periodic and aperiodic characteristics of the EEG signal. Across two independent datasets, we examined whether resting-state EEG changes linked to AD reflect true oscillatory (periodic) changes, changes in the aperiodic (non-oscillatory) signal, or a combination of both. We found strong evidence that the alterations are purely periodic in nature, with decreases in oscillatory power at alpha and beta frequencies (AD < HC) leading to lower (alpha + beta) / (delta + theta) power ratios in AD. Aperiodic EEG features did not differ between AD and HC. By replicating the findings in two cohorts, we provide robust evidence for purely oscillatory pathophysiology in AD and against aperiodic EEG changes. We therefore clarify the alterations underlying the neural dynamics in AD and emphasize the robustness of oscillatory AD signatures, which may further be used as potential prognostic or interventional targets in future clinical investigations.</p
Effects of targeted memory reactivation on cortical networks
Sleep is a complex physiological process with an important role in memory consolidation characterised by a series of spatiotemporal changes in brain activity and connectivity. Here, we investigate how task-related responses differ between pre-sleep wake, sleep, and post-sleep wake. To this end, we trained participants on a serial reaction time task using both right and left hands using Targeted Memory Reactivation (TMR), in which auditory cues are associated with learned material and then re-presented in subsequent wake or sleep periods in order to elicit memory reactivation. The neural responses just after each cue showed increased theta band connectivity between frontal and other cortical regions, as well as between hemispheres, in slow wave sleep compared to pre- or post-sleep wake. This pattern was consistent across the cues associated with both right- and left-handed movements. We also searched for hand-specific connectivity and found that this could be identified in within-hemisphere connectivity after TMR cues during sleep and post-sleep sessions. The fact that we could identify which hand had been cued during sleep suggests that these connectivity measures could potentially be used to determine how successfully memory is reactivated by our manipulation. Collectively, these findings indicate that TMR modulates the brain cortical networks showing clear differences between wake and sleep connectivity patterns
Neue Erzählformen in dynamischen Bildtechnologien - Formprobleme zwischen Populärkommunikation und autonomer Kunst
Jeder Fortschritt, jede Neuerung größeren Ausmaßes in verschiedenen Medien provoziert nach einer kurzen Phase spielerischen Experiments eine erneute Konsolidierung wie deren ästhetische Reflexion: Diese Dualität kennen wir spätestens seit den Tagen industrieller Kommunikation als eine Trennung zwischen Massenkommunikation und Kunst. Dies lässt sich gleichermaßen bei der Entwicklung des zentralperspektivischen Bildes, der frühen Fotografie oder ganz besonders der Kinematografie beobachten. Nach einer ersten Phase des Kinos der Attraktionen entwickelte sich eine neue und einzigartige Formensprache des Classical Style als konventionalisierte Gestaltungsregel des Films, die zugleich und teilweise in scharfer Opposition verschiedene Gegenbewegungen auslöste oder als deren explizite Reflexion durch individuelle künstlerische Formensprachen überformt wurde. Aktuell stehen wir vor einer ähnlichen Situation, der Erfindung und Verbreitung dreidimensionaler dynamischer Techniken mit Datenbrille und anderen Technologien, die neue Formen der Virtual Production und damit des Erzählens ermöglichen - sogenanntes 'spatial' oder 'environmental storytelling'. Der Band widmet sich diesem neuen Erzählen auf drei Ebenen: Raumbild und -ton (Film), Bewegung im Raum (Computerspiel und VR) und Raum als Kontext (AR)
Communicative signals during joint attention promote neural processes of infants and caregivers
Communicative signals such as eye contact increase infants’ brain activation to visual stimuli and promote joint attention. Our study assessed whether communicative signals during joint attention enhance infant-caregiver dyads’ neural responses to objects, and their neural synchrony. To track mutual attention processes, we applied rhythmic visual stimulation (RVS), presenting images of objects to 12-month-old infants and their mothers (n = 37 dyads), while we recorded dyads’ brain activity (i.e., steady-state visual evoked potentials, SSVEPs) with electroencephalography (EEG) hyperscanning. Within dyads, mothers either communicatively showed the images to their infant or watched the images without communicative engagement. Communicative cues increased infants’ and mothers’ SSVEPs at central-occipital-parietal, and central electrode sites, respectively. Infants showed significantly more gaze behaviour to images during communicative engagement. Dyadic neural synchrony (SSVEP amplitude envelope correlations, AECs) was not modulated by communicative cues. Taken together, maternal communicative cues in joint attention increase infants’ neural responses to objects, and shape mothers’ own attention processes. We show that communicative cues enhance cortical visual processing, thus play an essential role in social learning. Future studies need to elucidate the effect of communicative cues on neural synchrony during joint attention. Finally, our study introduces RVS to study infant-caregiver neural dynamics in social contexts
Developing an fMRI paradigm for studying reinforcement learning with gustatory stimuli
One of the main challenges for global public health in the modern world is the rising prevalence of obesity. Obtaining a better understanding of the dysregulated feeding behaviour that leads to obesity, by investigating the decision making and learning processes underlying it, could advance our capabilities in battling the obesity epidemic. Consequently, our aim in this study is to design an experiment that could evaluate these processes.
We examined ten healthy participants using a modified version of the "probabilistic selection task". We used gustatory stimuli as a replacement for monetary rewards, to assess the effect of nutritional rewards on the learning behaviour. We subsequently analysed the behavioural results with computational modelling and combined this with imaging data simultaneously acquired with a functional magnetic resonance imaging (fMRI) multiband sequence.
All participants in this study succeeded in interpreting and interacting with the gustatory stimuli appropriately. Performance on the task was affected by the subjective valuation of the reward. Participants whose motivation to drink the reward and liking of its taste decreased during the task presented difficulties correctly choosing the more rewarding cues.
Computational modelling of the behaviour found that the so-called asymmetric learning model, in which positive and negative reinforcement are differently weighted, best explained the group. The acquired fMRI data was suboptimal and we did not detect the neurological activity we expected in the reward system, which is central to our scientific question.
Thus, our study shows it is possible to implement the PST with gustatory stimuli. However, to evaluate the corresponding neurological activity, our fMRI configuration requires improvement. An optimised system could be used in further studies to improve our understanding of the neurobiological mechanisms of learning that lead to obesity and elucidate the role of food as a distinctive reinforcer
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