A night of sleep deprivation alters brain connectivity and affects specific executive functions.

Sleep is a fundamental physiological process necessary for efficient cognitive functioning especially in relation to memory consolidation and executive functions, such as attentional and switching abilities. The lack of sleep strongly alters the connectivity of some resting-state networks, such as default mode network and attentional network. In this study, by means of magnetoencephalography (MEG) and specific cognitive tasks, we investigated how brain topology and cognitive functioning are affected by 24 h of sleep deprivation (SD). Thirty-two young men underwent resting-state MEG recording and evaluated in letter cancellation task (LCT) and task switching (TS) before and after SD. Results showed a worsening in the accuracy and speed of execution in the LCT and a reduction of reaction times in the TS, evidencing thus a worsening of attentional but not of switching abilities. Moreover, we observed that 24 h of SD induced large-scale rearrangements in the functional network. These findings evidence that 24 h of SD is able to alter brain connectivity and selectively affects cognitive domains which are under the control of different brain networks.

Nutrition and cognition across the lifetime: an overview on epigenetic mechanisms.

The functioning of our brain depends on both genes and their interactions with environmental factors. The close link between genetics and environmental factors produces structural and functional cerebral changes early on in life. Understanding the weight of environmental factors in modulating neuroplasticity phenomena and cognitive functioning is relevant for potential interventions. Among these, nutrition plays a key role. In fact, the link between gut and brain (the gut-brain axis) is very close and begins in utero, since the Central Nervous System (CNS) and the Enteric Nervous System (ENS) originate from the same germ layer during the embryogenesis. Here, we investigate the epigenetic mechanisms induced by some nutrients on the cognitive functioning, which affect the cellular and molecular processes governing our cognitive functions. Furthermore, epigenetic phenomena can be positively affected by specific healthy nutrients from diet, with the possibility of preventing or modulating cognitive impairments. Specifically, we described the effects of several nutrients on diet-dependent epigenetic processes, in particular DNA methylation and histones post-translational modifications, and their potential role as therapeutic target, to describe how some forms of cognitive decline could be prevented or modulated from the early stages of life.

The effects of different frequencies of rhythmic acoustic stimulation on gait stability in healthy elderly individuals: a pilot study.

The efficacy of rhythmic acoustic stimulation (RAS) to improve gait and balance in healthy elderly individuals is controversial. Our aim was to investigate, through 3D gait analysis, the effect of different types of RAS (fixed frequency and based on subject-specific cadence), using conventional gait parameters and the trunk displacement as readouts. Walking at a fixed frequency of 80 bpm, the subjects showed extended duration of gait cycle and increased gait variability while the same individuals, walking at a fixed frequency of 120 bpm, showed reduced trunk sway and gait cycle duration. With regard to the RAS at subject-specific frequencies, walking at 90% of the subject-specific average cadence did not significantly modify the gait parameters, except for the speed, which was reduced. In contrast, walking at 100% and 110% of the mean cadence caused increased stride length and a slight reduction of temporal parameters and trunk sway. In conclusion, this pilot study shows that using RAS at fixed frequencies might be an inappropriate strategy, as it is not adjusted to individual gait characteristics. On the other hand, RAS frequencies equal to or slightly higher than each subject's natural cadence seem to be beneficial for gait and stability.

Functional brain network topology across the menstrual cycle is estradiol dependent and correlates with individual well-being.

The menstrual cycle (MC) is a sex hormone-related phenomenon that repeats itself cyclically during the woman's reproductive life. In this explorative study, we hypothesized that coordinated variations of multiple sex hormones may affect the large-scale organization of the brain functional network and that, in turn, such changes might have psychological correlates, even in the absence of overt clinical signs of anxiety and/or depression. To test our hypothesis, we investigated longitudinally, across the MC, the relationship between the sex hormones and both brain network and psychological changes. We enrolled 24 naturally cycling women and, at the early-follicular, peri-ovulatory, and mid-luteal phases of the MC, we performed: (a) sex hormone dosage, (b) magnetoencephalography recording to study the brain network topology, and (c) psychological questionnaires to quantify anxiety, depression, self-esteem, and well-being. We showed that during the peri-ovulatory phase, in the alpha band, the leaf fraction and the tree hierarchy of the brain network were reduced, while the betweenness centrality (BC) of the right posterior cingulate gyrus (rPCG) was increased. Furthermore, the increase in BC was predicted by estradiol levels. Moreover, during the luteal phase, the variation of estradiol correlated positively with the variations of both the topological change and environmental mastery dimension of the well-being test, which, in turn, was related to the increase in the BC of rPCG. Our results highlight the effects of sex hormones on the large-scale brain network organization as well as on their possible relationship with the psychological state across the MC. Moreover, the fact that physiological changes in the brain topology occur throughout the MC has widespread implications for neuroimaging studies.

Neuronal Avalanches to Study the Coordination of Large-Scale Brain Activity: Application to Rett Syndrome.

Many complex systems, such as the brain, display large-scale coordinated interactions that create ordered patterns. Classically, such patterns have been studied using the framework of criticality, i.e., at a transition point between two qualitatively distinct patterns. This kind of system is generally characterized by a scale-invariant organization, in space and time, optimally described by a power-law distribution whose slope is quantified by an exponent α. The dynamics of these systems is characterized by alternating periods of activations, called avalanches, with quiescent periods. To maximize its efficiency, the system must find a trade-off between its stability and ease of propagation of activation, which is achieved by a branching process. It is quantified by a branching parameter σ defined as the average ratio between the number of activations in consecutive time bins. The brain is itself a complex system and its activity can be described as a series of neuronal avalanches. It is known that critical aspects of brain dynamics are modeled with a branching parameter σ = , and the neuronal avalanches distribution fits well with a power law distribution exponent α = -3/2. The aim of our work was to study a self-organized criticality system in which there was a change in neuronal circuits due to genetic causes. To this end, we have compared the characteristics of neuronal avalanches in a group of 10 patients affected by Rett syndrome, during an open-eye resting-state condition estimated using magnetoencephalography, with respect to 10 healthy subjects. The analysis was performed both in broadband and in the five canonical frequency bands. We found, for both groups, a branching parameter close to 1. In this critical condition, Rett patients show a lower distribution parameter α in the delta and broadband. These results suggest that the large-scale coordination of activity occurs to a lesser extent in RTT patients.

Peripersonal Visuospatial Abilities in Williams Syndrome Analyzed by a Table Radial Arm Maze Task.

Williams syndrome (WS) is a genetic deletion syndrome characterized by severe visuospatial deficits affecting spatial exploration and navigation abilities in extra-personal space.To date, little is known about spatial elaboration and reaching abilities in the peripersonal space in individuals with WS. The present study is aimed at evaluating the visuospatial abilities in individuals with WS and comparing their performances with those of mental age-matched typically developing (TD) children by using a highly sensitive ecological version of the Radial Arm Maze (table RAM). We evaluated 15 individuals with WS and 15 TD children in two different table RAM paradigms: the free-choice paradigm, mainly to analyze the aspects linked to procedural and memory components, and the forced-choice paradigm, to disentangle the components linked to spatial working memory from the procedural ones.Data show that individuals with WS made significantly more working memory errors as compared with TD children, thus evidencing a marked deficit in resolving the task when the mnesic load increased. Our findings provide new insights on the cognitive profile of WS.

In Amyotrophic Lateral Sclerosis Blood Cytokines Are Altered, but Do Not Correlate with Changes in Brain Topology.

Aim: The present study aims at investigating the possible correlation between peripheral markers of inflammation and brain networks. Introduction: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease dominated by progressive motor impairment. Among the complex mechanisms contributing to the pathogenesis of the disease, neuroinflammation, which is associated with altered circulating cytokine levels, is suggested to play a prominent role. Methods: Based on magnetoencephalography data, we estimated topological properties of the brain networks in ALS patients and healthy controls. Subsequently, the blood levels of a subset of cytokines were assayed. Finally, we modeled the brain topological features in the function of the cytokine levels. Results: Significant differences were found in the levels of the cytokines interleukin (IL)-4, IL-1ß, and interferon-gamma (IFN-γ) between patients and controls. In particular, IL-4 and IL-1ß levels increased in ALS patients, while the IFN-γ level was higher in healthy controls. We also detected modifications in brain global topological parameters in terms of hyperconnectedness. Despite both blood cytokines and brain topology being altered in ALS patients, such changes do not appear to be in a direct relationship. Conclusion: Our results would be in line with the idea that topological changes relate to neurodegenerative processes. However, the absence of correlation between blood cytokines and topological parameters of brain networks does not preclude that inflammatory processes contribute to the alterations of the brain networks. Impact statement The progression of amyotrophic lateral sclerosis entails both neurodegenerative and inflammatory processes. Furthermore, disease progression induces global modifications of the brain networks, with advanced stages showing a more compact, hyperconnected network topology. The pathophysiological processes underlying topological changes are unknown. In this article, we hypothesized that the global inflammatory profile would relate to the topological alterations. Our results showed that this is not the case, as modeling the topological properties as a function of the inflammatory state did not yield good predictions. Hence, our results suggest that topological changes might directly relate to neurodegenerative processes instead.

The Development of Spatial Memory Analyzed by Means of Ecological Walking Task.

The present study is aimed at investigating the development of spatial memory in pre-school children aged 4-6 years using an ecological walking task with multiple rewards. The participants were to explore an open space in order to find nine rewards placed in buckets arranged in three spatial configurations: a Cross, a 3 × 3 Matrix, and a Cluster composed of three groups of three buckets each. Clear age-related improvements were evident in all the parameters analyzed. In fact, there was a general trend for younger children to display worse performance than the older ones. Moreover, males performed better than females in both the search efficiency and visiting all buckets. Additionally, the search efficiency proved to be a function of the difficulty of the configuration to be explored: the Matrix and Cluster configurations were easier to explore than the Cross configuration. Taken altogether, the present findings suggest that there is a general improvement in the spatial memory abilities in preschoolers and that solving an open space task could be influenced by gender. Moreover, it can be proposed that both the procedural competences and the memory load requested to explore a specific environment are determined by its specific features.

Effects of pre-reproductive maternal enrichment on maternal care, offspring's play behavior and oxytocinergic neurons.

Potentiating social, cognitive, and sensorimotor stimulations the Environmental Enrichment (EE) increases levels of novelty and complexity experienced by individuals. Growing evidence demonstrates that parental EE experience, even occurring in the pre-reproductive phase, affects behavioral and neural developmental trajectories of the offspring. To discover how the accumulation of early maternal complex experiences may inform and shape the social behavior of the following generation, we examined the effects of pre-reproductive enrichment of dams (post-natal days 21-72) on the play performances of their male and female adolescent offspring. Furthermore, we examined the effects of pre-reproductive enrichment on maternal behavior (during post-partum days 1-10) and male intruder aggression (on post-partum day 11). Since oxytocin modulates maternal care, social bonding, and agonistic behavior, the number of oxytocinergic neurons of the paraventricular (PVN) and supraoptic (SON) nuclei was examined in both dams and offspring. Results revealed that enriched females exhibited higher levels of pup-oriented behaviors, especially Crouching, and initiated pup-retrieval more quickly than standard females after the maternal aggression test. Such behavioral peculiarities were accompanied by increased levels of oxytocinergic neurons in PVN and SON. Moreover, pre-reproductive maternal EE cross-generationally influenced the offspring according to sex. Indeed, male pups born to enriched females exhibited a reduced play fighting associated with a higher number of oxytocinergic neurons in SON in comparison to male pups born to standard-housed females. In conclusion, pre-reproductive EE to the mothers affects their maternal care and has a cross-generational impact on the social behavior of their offspring that do not directly experiences EE. This article is part of the Special Issue entitled "Neurobiology of Environmental Enrichment".

Executive functioning profiles in elite volleyball athletes: Preliminary results by a sport-specific task switching protocol.

Executive functions (EF) are crucial for the athletes' success, and they are even more essential in open skill sports (e.g. volleyball and football). In these sports, due to continuously changing conditions, goal-directed behaviours need to be repeatedly adjusted and corrected. One of the most important EF is the ability to continuously switch between two different tasks being required in a random sequence. We used a task-switching protocol in elite volleyball athletes, usually playing different roles, with the aim of evaluating if each role is characterized by specific switching abilities. On the basis of the specific competences requested by the game, thirty-six elite volleyball athletes were assigned to three groups: Strikers, Defenders and Mixed. Each player completed a customized sport-specific task-switching paradigm. Data evidenced that each role has specific characteristics. In Reaction Times, the Strikers were the fastest to answer to stimuli, while the Defender group provided a worse performance, particularly when defensive actions, that probably require more cognitive elaboration, had to be processed. Different effects emerged by the Errors. In fact, the Mixed group, which was the one with more expertise, appeared to be more accurate in the responses. Although preliminary, these results showed a minimal degree of cognitive flexibility for highly specialized Strikers and a maximum level for Mixed, allowing thus to highlight specific profiles of athletes. Data observed indicate the possibility to develop a test assessing the executive domain during the recruitment in a team, revealing a useful tool for choosing the most suitable role.

Mindfulness Meditation Is Related to Long-Lasting Changes in Hippocampal Functional Topology during Resting State: A Magnetoencephalography Study.

It has been suggested that the practice of meditation is associated to neuroplasticity phenomena, reducing age-related brain degeneration and improving cognitive functions. Neuroimaging studies have shown that the brain connectivity changes in meditators. In the present work, we aim to describe the possible long-term effects of meditation on the brain networks. To this aim, we used magnetoencephalography to study functional resting-state brain networks in Vipassana meditators. We observed topological modifications in the brain network in meditators compared to controls. More specifically, in the theta band, the meditators showed statistically significant (p corrected = 0.009) higher degree (a centrality index that represents the number of connections incident upon a given node) in the right hippocampus as compared to controls. Taking into account the role of the hippocampus in memory processes, and in the pathophysiology of Alzheimer's disease, meditation might have a potential role in a panel of preventive strategies.

Influence of Pre-reproductive Maternal Enrichment on Coping Response to Stress and Expression of c-Fos and Glucocorticoid Receptors in Adolescent Offspring.

Environmental enrichment (EE) is an experimental setting broadly used for investigating the effects of complex social, cognitive, and sensorimotor stimulations on brain structure and function. Recent studies point out that parental EE experience, even occurring in the pre-reproductive phase, affects neural development and behavioral trajectories of the offspring. In the present study we investigated the influences of pre-reproductive EE of female rats on maternal behavior and adolescent male offspring's coping response to an inescapable stressful situation after chronic social isolation. For this purpose female Wistar rats were housed from weaning to breeding age in enriched or standard environments. Subsequently, all females were mated and housed in standard conditions until offspring weaning. On the first post partum day (ppd 1), mother-pup interactions in undisturbed conditions were recorded. Further, after weaning the male pups were reared for 2 weeks under social isolation or in standard conditions, and then submitted or not to a single-session Forced Swim Test (FST). Offspring's neuronal activation and plastic changes were identified by immunohistochemistry for c-Fos and glucocorticoid receptors (GRs), and assessed by using stereological analysis. The biochemical correlates were measured in the hippocampus, amygdala and cingulate cortex, structures involved in hypothalamic-pituitary-adrenocortical axis regulation. Enriched dams exhibited increased Crouching levels in comparison to standard reared dams. In the offspring of both kinds of dams, social isolation reduced body weight, decreased Immobility, and increased Swimming during FST. Moreover, isolated offspring of enriched dams exhibited higher levels of Climbing in comparison to controls. Interestingly, in the amygdala of both isolated and control offspring of enriched dams we found a lower number of c-Fos immunopositive cells in response to FST and a higher number of GRs in comparison to the offspring of standard dams. These results highlight the profound influence of a stressful condition, such as the social isolation, on the brain of adolescent rats, and underline intergenerational effects of maternal experiences in regulating the offspring response to stress.