Influence of age and cognitive performance on resting-state functional connectivity of dopaminergic and noradrenergic centers

Aging is associated with structural and functional changes in the brain, with a decline in cognitive functions observed as its inevitable concomitant. The body of literature suggests dopamine and noradrenaline as prominent candidate neuromodulators to mediate these effects; however, knowledge regarding the underlying mechanisms is scarce. To fill this gap, we compared resting-state functional connectivity (FC) patterns of ventral tegmental area (VTA), substantia nigra pars compacta (SNc) and locus coeruleus (LC) in healthy young (20–35 years; N = 37) and older adults (55–80 years; N = 27). Additionally, we sought FC patterns of these structures associated with performance in tasks probing executive, attentional and reward functioning, and we compared the functional coupling of the bilateral SNc. The results showed that individual SNc had stronger coupling with ipsilateral cortical and subcortical areas along with the contralateral cerebellum in the whole sample, and that the strength of connections of this structure with angular gyrus and lateral orbitofrontal cortex predicted visuomotor search abilities. In turn, older age was associated with greater local synchronization within VTA, its lower FC with caudate, mediodorsal thalamus, and SNc, as well as higher FC of both midbrain dopaminergic seeds with red nuclei. LC functional coupling showed no differences between the groups and was not associated with any of the behavioral functions. To the best of our knowledge, this work is the first to report the age-related effects on VTA local synchronization and its connectivity with key recipients of dopaminergic innervation, such as striatum and mediodorsal thalamus

Scaling of solvation force in 2D Ising strip

The solvation force for the 2D Ising strip is calculated via exact diagonalization of the transfer matrix in two cases: the symmetric case corresponds to identical surface fields, and the antisymmetric case to exactly opposite surface fields. In the symmetric case the solvation force is always negative (attractive) while in the antisymmetric case the solvation force is positive (repulsive) at high temperatures and negative at low temperatures. It changes sign close to the critical wetting temperature characterizing the semi--infinite system. The properties of the solvation force are discussed and the scaling function describing its dependence on temperature, surface field, and strip's width is proposed

Modification of emission properties of ZnO layers due to plasmonic near-field coupling to Ag nanoislands

A simple fabrication method of Ag nanoislands on ZnO films is presented. Continuous wave and time-resolved photoluminescence and transmission are employed to investigate modifications of visible and UV emissions of ZnO brought about by coupling to localized surface plasmons residing on Ag nanoislands. The size of the nanoislands, determining their absorption and scattering efficiencies, is found to be an important factor governing plasmonic modification of optical response of ZnO films. The presence of the Ag nanoislands of appropriate dimensions causes a strong (threefold) increase in emission intensity and up to 1.5 times faster recombination. The experimental results are successfully described by model calculations within the Mie theory.Comment: 14 pages, 5 figure

Excess body weight as a risk factor to well-being and performance of flight personnel : potential strategies of prevention

Flight personnel is at risk of excessive weight and obesity. This is due to, for instance, irregular work schedules, irregular nutritional habits, excessive workload, and an inability to plan regular physical exercise or recreation. These factors lead to excessive body weight gains, and hence to obesity. Obesity directly infl uences quality of life as well as readiness to fulfi ll duties by the aircraft maintenance personnel. Obesity is an independent risk factor for various diseases such as hypertension, type 2 diabetes, coronary artery disease, atherosclerosis, each of which can lead to a loss of medical licence. Obesity is associated with extensive caloric consumption that cannot be controlled by the aff ected person. State of the art research has demonstrated not only hormonal and neuronal changes associated with obesity, but also points to deterioration of cognitive functions; these changes are likely induced by suboptimal diets. Furthermore, we will review prevention strategies, as well as treatments aimed at losing weight in fl ight personnel already aff ected by obesity. Implementation of these programs may prolong the time a pilot is fi t to fl y and improve his/her performance

Non-invasive vagus nerve stimulation in treatment of disorders of consciousness : longitudinal case study

Neuromodulatory electroceuticals such as vagus nerve stimulation have been recently gaining traction as potential rehabilitation tools for disorders of consciousness (DoC). We present a longitudinal case study of non-invasive auricular vagus nerve stimulation (taVNS) in a patient diagnosed with chronic unresponsive wakefulness syndrome (previously known as vegetative state). Over a period of 6 months we applied taVNS daily and regularly evaluated the patient’s behavioral outcomes using Coma Recovery Scale - Revised. We also took electrophysiological measures: resting state electroencephalography (EEG), heart rate (HR) and heart rate variability (HRV). All these methods revealed signs of improvement in the patient’s condition. The total CRS-R scores fluctuated but rose from 4 and 6 at initial stages to the heights of 12 and 13 in the 3rd and 5th month, which would warrant a change in diagnosis to a Minimally Conscious State. Scores obtained in a 2 months follow-up period, though, suggest this may not have been a lasting improvement. Behavioral signs of recovery are triangulated by EEG frequency spectrum profiles with re-emergence of a second oscillatory peak in the alpha range, which has been shown to characterize aware people. However, sustained spontaneous theta oscillations did not predictably diminish, which most likely reflects structural brain damage. ECG measures revealed a steady decrease in pre-stimulation HR combined with an increase in HRV-HR. This suggests a gradual withdrawal of sympathetic and an increase in parasympathetic control of the heart, which the previous literature has also linked with DoC improvements. Together, this study suggests that taVNS stimulation holds promise as a DoC treatment

Critical region for droplet formation in the two-dimensional Ising model

We study the formation/dissolution of equilibrium droplets in finite systems at parameters corresponding to phase coexistence. Specifically, we consider the 2D Ising model in volumes of size $L^2$, inverse temperature \beta>\betac and overall magnetization conditioned to take the value \mstar L^2-2\mstar v_L, where \betac^{-1} is the critical temperature, \mstar=\mstar(\beta) is the spontaneous magnetization and $v_L$ is a sequence of positive numbers. We find that the critical scaling for droplet formation/dissolution is when $v_L^{3/2} L^{-2}$ tends to a definite limit. Specifically, we identify a dimensionless parameter $\Delta$, proportional to this limit, a non-trivial critical value \Deltac and a function $\lambda_\Delta$ such that the following holds: For \Delta<\Deltac, there are no droplets beyond $\log L$ scale, while for \Delta>\Deltac, there is a single, Wulff-shaped droplet containing a fraction \lambda_\Delta\ge\lamc=2/3 of the magnetization deficit and there are no other droplets beyond the scale of $\log L$. Moreover, $\lambda_\Delta$ and $\Delta$ are related via a universal equation that apparently is independent of the details of the system.Comment: 48 pages, 2 figures, version to appear in Commun. Math. Phy

Imaging of hypnosis with functional magnetic resonance

Aim. The aim of the study was imaging of the central nervous system activity with the fMRI method during hypnosis as well as confirmation of the observations linking subjective effects of suggested analgesia with the functional changes on the neurophysiological level. Method. At first volunteers (7 female, 7 male) were examined with fMRI in the resting state and then four times during application of painful stimuli such as pricking of the right hand. Four experimental conditions were associated with this stimulation: only nociceptive stimulation, after analgesic suggestion, after hypnotic induction and after consecutive analgesic suggestion in hypnosis. In the fifth condition, concentration of attention was an experimental condition, while the control condition was distraction of attention (e.g. free associations). The contrast differences between measurements in the consecutive phases of the experiment were analysed. Results. Decreases of activity of regions known for contributing to pain reception were found, probably as an effect of analgesic suggestion. This effect was seen especially in the area of L-thalamus. Suggestion (more precisely - the reception of its content) was related mainly to the R-ACG area activity growth. Hypnotic induction was correlated with increasing activity of the L-orbitofrontal gyrus. Concentration of attention was linked with activity increase within inferior parietal lobule, occipital middle/superior gyri; in the left hemisphere in the orbital frontal gyri and insula/frontal operculum. Conclusion. Both hypnosis and reception of analgesic suggestion are linked with increasing activity in particular brain areas, whereas the effect of analgesic suggestion demonstrates itself in the fMRI mainly by diminishing the reaction on painful stimuli

Real life changes in physical activity due to intragastric balloon therapy and their relationship to improving cognitive functions : preliminary findings

Background. We evaluated if the intragastric balloon (IGB) treatment leads to the increase in physical activity (PA) and whether they are related to cognitive improvements. Methods. Fourteen morbidly obese patients (151 ± 24 kg, BMI = 51.8 ± 6.5, 107 ± 26% excess weight, 43.3 ± 10.6 years) underwent 6-day-long, uninterrupted evaluations of PA 1 month before IGB insertion and 1 month after its removal. Results Active energy expenditure and physical activity duration increased by more than 80% (p < 0.001) whereas the number of steps per day by 20% (p = 0.016). There was a pattern of relationships between cognitive improvements and increases in PA (p < 0.05). In particular, working memory improvements correlated with the increase in time spent on light physical activities (r = 0.673, p = 0.004). Conclusion. The relationships suggest that an increase in physical activity mediates cognitive improvements in bariatric patients

Brain activity underlying response induced by SNARC-congruent and SNARC-incongruent stimuli

At least three well‑documented phenomena indicate a relationship between numbers and the internal representation of space. They are shifting attention in accordance with the localization of numbers on the mental number line (MNL); the spatial‑numerical association of response codes (SNARC) effect, which manifests as faster responses to high numbers with the right hand than with the left, and vice versa for low numbers; and the processing of both numbers and space primarily in the parietal cortex. Some EEG studies have pointed to the response selection stage as a locus of this effect. However, this explanation has yet to be corroborated by the fMRI experiments.The goal of this study was to investigate the functional anatomy underlying response selection induced by SNARC‑congruent and SNARC-incongruent stimuli in a spatial visual cueing task. Healthy adult volunteers responded to a pair of target stimuli consisting of digits, non-digit symbols, or a mix of both. In each trial, the stimuli were preceded by a centrally presented numerical or non-numerical cue stimulus which was required to be memorized. One of the target stimuli that then appeared would be identical to the cue; the task was to determine which side it was presented on, within the pair. In the case of numerical stimuli, the side was congruent with its localization on the MNL in one‑half of the trials. In the other half of the trials, it was incongruent. The behavioral results revealed the SNARC effect, as well as a faster reaction to low numbers than to high numbers. The fMRI responses to the target stimuli showed engagement of regions implicated in number processing but also in sensory-motor areas. This suggests that the motor response selection or execution stage may be the locus of the SNARC effect. Yet, the activation pattern obtained in the congruent and incongruent conditions did not allow us to determine, indisputably, the neural correlates of the mechanisms involved in the SNARC effect. Moreover, we did not observe any stimulus-specific responses to cues