Growing evidence from the dynamical analysis of functional neuroimaging data suggests that brain function can be understood as the exploration of a repertoire of metastable connectivity patterns ('functional brain networks'), which potentially underlie different mental processes.The present study characterizes how the brain's dynamical exploration of resting--state networks is rapidly modulated by intravenous infusion of psilocybin, a tryptamine psychedelic found in "magic mushrooms". We employed a data--driven approach to characterize recurrent functional connectivity patterns by focusing on the leading eigenvector of BOLD phase coherence at single--TR resolution. Recurrent BOLD phase--locking patterns (PL states) were assessed and statistically compared pre--and post--infusion of psilocybin in terms of their probability of occurrence and transition profiles. Results were validated using a placebo session.Recurrent BOLD PL states revealed high spatial overlap with canonical resting--state networks. Notably, a PL state forming a frontoparietal subsystem was strongly destabilized after psilocybin injection, with a concomitant increase in the probability of occurrence of another PL state characterized by global BOLD phase coherence. These findings provide Recently, a number of methodological approaches have been proposed to analyze BOLD connectivity dynamics at high temporal resolution (i.e., single volume / TR), focusing either on BOLD co--activation patterns (

The modern understanding of sleep is based on the classification of sleep into stages defined by their electroencephalography (EEG) signatures, but the underlying brain dynamics remain unclear. Here we aimed to move significantly beyond the current state-of-the-art description of sleep, and in particular to characterise the spatiotemporal complexity of whole-brain networks and state transitions during sleep. In order to obtain the most unbiased estimate of how whole-brain network states evolve through the human sleep cycle, we used a Markovian data-driven analysis of continuous neuroimaging data from 57 healthy participants falling asleep during simultaneous functional magnetic resonance imaging (fMRI) and EEG. This Hidden Markov Model (HMM) facilitated discovery of the dynamic choreography between different whole-brain networks across the wake-non-REM sleep cycle. Notably, our results reveal key trajectories to switch within and between EEG-based sleep stages, while highlighting the heterogeneities of stage N1 sleep and wakefulness before and after sleep.

Neurobiological models to explain vulnerability of major depressive disorder (MDD) are scarce and previous functional magnetic resonance imaging studies mostly examined “static” functional connectivity (FC). Knowing that FC constantly evolves over time, it becomes important to assess how FC dynamically differs in remitted‐MDD patients vulnerable for new depressive episodes. Using a recently developed method to examine dynamic FC, we characterized re‐emerging FC states during rest in 51 antidepressant‐free MDD patients at high risk of recurrence (≥2 previous episodes), and 35 healthy controls. We examined differences in occurrence, duration, and switching profiles of FC states after neutral and sad mood induction. Remitted MDD patients showed a decreased probability of an FC state (p < 0.005) consisting of an extensive network connecting frontal areas—important for cognitive control—with default mode network, striatum, and salience areas, involved in emotional and self‐referential processing. Even when this FC state was observed in patients, it lasted shorter (p < 0.005) and was less likely to switch to a smaller prefrontal–striatum network (p < 0.005). Differences between patients and controls decreased after sad mood induction. Further, the duration of this FC state increased in remitted patients after sad mood induction but not in controls (p < 0.05). Our findings suggest reduced ability of remitted‐MDD patients, in neutral mood, to access a clinically relevant control network involved in the interplay between externally and internally oriented attention. When recovering from sad mood, remitted recurrent MDD appears to employ a compensatory mechanism to access this FC state. This study provides a novel neurobiological profile of MDD vulnerability.

Prevailing theories hold that the insula is functionally organized along its caudal-to-rostral axis, with posterior regions coding lower-level sensory information, and anterior regions coding higherlevel stimulus significance relative to the body's homeostatic needs. Contrary to predictions of this model, the response of the taste-sensitive region of the caudal, but not rostral, insula to food images was directly related to the body's homeostatic state as indexed by levels of peripheral glucose.It is widely held that there exists along the insula a caudal-to-rostral functional organization, with more caudal regions representing primarily lower-level sensory interoceptive, gustatory, and somatosensory signals, and rostral regions contributing to higher-level cognition and emotion by integrating information about the body's homeostatic state with information represented in limbic and executive control networks 1,2 . Although the neuroanatomical connections between the insula and peripheral nervous system suggest that homeostatic integration occurs in more caudal insular regions, particularly in the mid-insula where gustatory and visceral information from cranial nerves VII, IX, and X first reaches the cerebral cortex via subcortical projections though the brainstem and thalamus 3 , it is also frequently asserted that anterior insula integrates this homeostatic information about the state of the body with higher cognitive functions.A direct empirical test of the prevailing account within a single group of individuals would require identifying a sensory stimulus that activates both rostral and caudal regions of the Users may view, print, copy, download and text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Word count: 4872Abstract How we process ongoing experiences is shaped by our personal history, current needs, and future goals. Consequently, brain regions involved in generating these subjective appraisals, such as the vmPFC, often appear to be heterogeneous across individuals even in response to the same external information. To elucidate the role of the vmPFC in processing our ongoing experiences, we developed a computational framework and analysis pipeline to characterize the spatiotemporal dynamics of individual vmPFC responses as participants viewed a 45-minute television drama. Through a combination of functional magnetic resonance imaging, facial expression tracking, and self-reported emotional experiences across four studies, our data suggest that the vmPFC slowly transitions through a series of discretized states that broadly map onto affective experiences. Although these transitions typically occur at idiosyncratic times across people, participants exhibited a marked increase in state alignment during high affectively valenced events in the show. Our work suggests that the vmPFC ascribes affective meaning to our ongoing experiences.

How we process ongoing experiences is shaped by our personal history, current needs, and future goals. Consequently, ventromedial prefrontal cortex (vmPFC) activity involved in processing these subjective appraisals appears to be highly idiosyncratic across individuals. To elucidate the role of the vmPFC in processing our ongoing experiences, we developed a computational framework and analysis pipeline to characterize the spatiotemporal dynamics of individual vmPFC responses as participants viewed a 45-minute television drama. Through a combination of functional magnetic resonance imaging, facial expression tracking, and self-reported emotional experiences across four studies, our data suggest that the vmPFC slowly transitions through a series of discretized states that broadly map onto affective experiences. Although these transitions typically occur at idiosyncratic times across people, participants exhibited a marked increase in state alignment during high affectively valenced events in the show. Our work suggests that the vmPFC ascribes affective meaning to our ongoing experiences.

Obesity is a major public health concern that involves an interaction between genetic susceptibility and exposure to environmental cues (e.g., food marketing); however, the mechanisms that link these factors and contribute to unhealthy eating are unclear. Using a well-known obesity risk polymorphism (FTO rs9939609) in a sample of 78 children (ages 9-12 y), we observed that children at risk for obesity exhibited stronger responses to food commercials in the nucleus accumbens (NAcc) than children not at risk. Similarly, children at a higher genetic risk for obesity demonstrated larger NAcc volumes. Although a recessive model of this polymorphism best predicted body mass and adiposity, a dominant model was most predictive of NAcc size and responsivity to food cues. These findings suggest that children genetically at risk for obesity are predisposed to represent reward signals more strongly, which, in turn, may contribute to unhealthy eating behaviors later in life.T he relationship between genes and sensitivity to environmental cues is elusive, yet it is paramount to understanding the development of potentially maladaptive human behaviors. The rising prevalence of obesity is a major public health concern that has been attributed to various factors, such as genetic susceptibility (1), and increases in the availability and marketing of calorie-dense foods (2). However, little is known about how genetic predisposition to obesity influences sensitivity to real-world food cues and contributes to the development of unhealthy eating behaviors.Previous neuroimaging studies have demonstrated that responses to food cues in reward-related regions of the brain, such as the nucleus accumbens (NAcc), predict weight gain in adulthood (3) and giving in to food temptations in daily life (4). Furthermore, structural differences in NAcc volume have been positively associated with body mass index (BMI) in adults (5, 6). Because the development of the NAcc precedes the development of prefrontal control systems (7), this structure is suggested to play a key role in motivating and establishing unhealthy eating behaviors early in the lifespan. Importantly, genetic factors are a known contributor to brain development (8) and may influence risky behaviors during childhood and adolescence by biasing the early development of anatomical structures underlying reward-related brain function.In addition, the notion that genes contribute to obesity has recently gained much attention. More specifically, the fat-mass and obesity-associated (FTO) rs9939609 polymorphism has been strongly related to increased BMI and adiposity across the lifespan, and is suggested to influence food intake and food choice, rather than energy expenditure (9-11). Those with two high-risk "A" alleles (AA) are at an enhanced risk for obesity compared with those with two low-risk "T" alleles (TT) or those who are heterozygous (AT) for the FTO rs9939609 polymorphism. Although the FTO gene is highly expressed in the brain (1), the mechanism by which this gene promotes unhealthy...

The prevalence of obesity in children and adolescents worldwide has quadrupled since 1975 and is a key predictor of obesity later in life. Previous work has consistently observed relationships between macroscale measures of reward-related brain regions (e.g., the nucleus accumbens [NAcc]) and unhealthy eating behaviors and outcomes; however, the mechanisms underlying these associations remain unclear. Recent work has highlighted a potential role of neuroinflammation in the NAcc in animal models of diet-induced obesity. Here, we leverage a diffusion MRI technique, restriction spectrum imaging, to probe the microstructure (cellular density) of subcortical brain regions. More specifically, we test the hypothesis that the cell density of reward-related regions is associated with obesity-related metrics and early weight gain. In a large cohort of nine- and ten-year-olds enrolled in the Adolescent Brain Cognitive Development (ABCD) study, we demonstrate that cellular density in the NAcc is related to individual differences in waist circumference at baseline and is predictive of increases in waist circumference after 1 y. These findings suggest a neurobiological mechanism for pediatric obesity consistent with rodent work showing that high saturated fat diets increase gliosis and neuroinflammation in reward-related brain regions, which in turn lead to further unhealthy eating and obesity.