Anodal transcranial direct current stimulation enhances the efficiency of functional brain network communication during auditory attentional control.

Attentional control is crucial for selectively attending to relevant information when our brain is confronted with a multitude of sensory signals. Graph-theoretical measures provide a powerful tool for investigating the efficiency of brain network communication in separating and integrating information. Albeit, it has been demonstrated that anodal transcranial direct current stimulation (atDCS) can boost auditory attention in situations with high control demands, its effect on neurophysiological mechanisms of functional brain network communication in situations when attentional focus conflicts with perceptual saliency remain unclear. This study investigated the effects of atDCS on network connectivity and θ-oscillatory power under different levels of attentional-perceptual conflict. We hypothesized that the benefit of atDCS on network communication efficiency would be particularly apparent in conditions requiring high attentional control. Thirty young adults participated in a dichotic listening task with intensity manipulation, while EEG activity was recorded. In a cross-over design, participants underwent right frontal atDCS and sham stimulations in two separate sessions. Time-frequency decomposition and graph-theoretical analyses of network efficiency (using "small-world" properties) were used to quantify θ-oscillatory power and brain network efficiency, respectively. The atDCS-induced effect on task efficiency in the most demanding condition was mirrored only by an increase in network efficiency during atDCS compared with the sham stimulation. These findings are corroborated by Bayesian analyses. AtDCS-induced performance enhancement under high levels of attentional-perceptual conflicts is accompanied by an increase in network efficiency. Graph-theoretical measures can serve as a metric to quantify the effects of noninvasive brain stimulation on the separation and integration of information in the brain.NEW & NOTEWORTHY As compared with sham stimulation, application of atDCS enhances θ-oscillation-based network efficiency, but it has no impact on θ-oscillation power. Individual differences in θ-oscillation-based network efficiency correlated with performance efficiency under the sham stimulation.

Seven- to 11-Year-Olds' Developing Ability to Recognize Natural Facial Expressions of Basic Emotions.

Being able to recognize facial expressions of basic emotions is of great importance to social development. However, we still know surprisingly little about children's developing ability to interpret emotions that are expressed dynamically, naturally, and subtly, despite real-life expressions having such appearance in the vast majority of cases. The current research employs a new technique of capturing dynamic, subtly expressed natural emotional displays (happy, sad, angry, shocked, and disgusted). Children aged 7, 9, and 11 years (and adults) were systematically able to discriminate each emotional display from alternatives in a five-way choice. Children were most accurate in identifying the expression of happiness and were also relatively accurate in identifying the expression of sadness; they were far less accurate than adults in identifying shocked and disgusted. Children who performed well academically also tended to be the most accurate in recognizing expressions, and this relationship maintained independently of chronological age. Generally, the findings testify to a well-developed ability to recognize very subtle naturally occurring expressions of emotions.

Cortical processes of multisensory plausibility modulation of vibrotactile perception in virtual environments in middled-aged and older adults.

Digital technologies, such as virtual or augmented reality, can potentially support neurocognitive functions of the aging populations worldwide and complement existing intervention methods. However, aging-related declines in the frontal-parietal network and dopaminergic modulation which progress gradually across the later periods of the adult lifespan may affect the processing of multisensory congruence and expectancy based contextual plausibility. We assessed hemodynamic brain responses while middle-aged and old adults experienced car-riding virtual-reality scenarios where the plausibility of vibrotactile stimulations was manipulated by delivering stimulus intensities that were either congruent or incongruent with the digitalized audio-visual contexts of the respective scenarios. Relative to previous findings observed in young adults, although highly plausible vibrotactile stimulations confirming with contextual expectations also elicited higher brain hemodynamic responses in middle-aged and old adults, this effect was limited to virtual scenarios with extreme expectancy violations. Moreover, individual differences in plausibility-related frontal activity did not correlate with plausibility violation costs in the sensorimotor cortex, indicating less systematic frontal context-based sensory filtering in older ages. These findings have practical implications for advancing digital technologies to support aging societies.

Neural correlates of home-based intervention effects on value-based sequential decision-making in healthy older adults.

Older adults demonstrate difficulties in sequential decision-making, which is partly attributed to under-recruitment of prefrontal networks. It is, therefore, important to understand the mechanisms that may improve this ability. This study investigated the effectiveness of an 18-sessions, home-based cognitive intervention and the neural mechanisms that underpin individual differences in intervention effects. Participants were required to learn sequential choices in a 3-stage Markov decision-making task that would yield the most rewards. Participants were assigned to better or worse responders group based on their performance at the last intervention session (T18). Better responders improved significantly starting from the fifth intervention session while worse responders did not improve across all training sessions. At post-intervention, only better responders showed condition-dependent modulation of the dorsolateral prefrontal cortex (DLPFC) as measured by fNIRS, with higher DLPFC activity in the delayed condition. Despite large individual differences, our data showed that value-based sequential-decision-making and its corresponding neural mechanisms can be remediated via home-based cognitive intervention in some older adults; moreover, individual differences in recruiting prefrontal activities after the intervention are associated with variations in intervention outcomes. Intervention-related gains were also maintained at three months after post-intervention. However, future studies should investigate the potential of combining other intervention methods such as non-invasive brain stimulation with cognitive intervention for older adults who do not respond to the intervention, thus emphasizing the importance of developing individualized intervention programs for older adults.

Congruence-based contextual plausibility modulates cortical activity during vibrotactile perception in virtual multisensory environments.

How congruence cues and congruence-based expectations may together shape perception in virtual reality (VR) still need to be unravelled. We linked the concept of plausibility used in VR research with congruence-based modulation by assessing brain responses while participants experienced vehicle riding experiences in VR scenarios. Perceptual plausibility was manipulated by sensory congruence, with multisensory stimulations confirming with common expectations of road scenes being plausible. We hypothesized that plausible scenarios would elicit greater cortical responses. The results showed that: (i) vibrotactile stimulations at expected intensities, given embedded audio-visual information, engaged greater cortical activities in frontal and sensorimotor regions; (ii) weaker plausible stimulations resulted in greater responses in the sensorimotor cortex than stronger but implausible stimulations; (iii) frontal activities under plausible scenarios negatively correlated with plausibility violation costs in the sensorimotor cortex. These results potentially indicate frontal regulation of sensory processing and extend previous evidence of contextual modulation to the tactile sense.

Neurocognitive development of novelty and error monitoring in children and adolescents.

The abilities to monitor one's actions and novel information in the environment are crucial for behavioural and cognitive control. This study investigated the development of error and novelty monitoring and their electrophysiological correlates by using a combined flanker with novelty-oddball task in children (7-12 years) and adolescents (14-18 years). Potential moderating influences of prenatal perturbation of steroid hormones on these performance monitoring processes were explored by comparing individuals who were prenatally exposed and who were not prenatally exposed to synthetic glucocorticoids (sGC). Generally, adolescents performed more accurately and faster than children. However, behavioural adaptations to error or novelty, as reflected in post-error or post-novelty slowing, showed different developmental patterns. Whereas post-novelty slowing could be observed in children and adolescents, error-related slowing was absent in children and was marginally significant in adolescents. Furthermore, the amplitude of error-related negativity was larger in adolescents, whereas the amplitude of novelty-related N2 was larger in children. These age differences suggest that processes involving top-down processing of task-relevant information (for instance, error monitoring) mature later than processes implicating bottom-up processing of salient novel stimuli (for instance, novelty monitoring). Prenatal exposure to sGC did not directly affect performance monitoring but initial findings suggest that it might alter brain-behaviour relation, especially for novelty monitoring.

Syndecan-2 regulates the migratory potential of melanoma cells.

Syndecan-2, a transmembrane heparan sulfate proteoglycan, is a critical mediator in the tumorigenesis of colon carcinoma cells. We explored the function of syndecan-2 in melanoma, one of the most invasive types of cancers, and found that the expression of this protein was elevated in tissue samples from both nevus and malignant human melanomas but not in melanocytes of the normal human skin tissues. Similarly, elevated syndecan-2 expression was observed in various melanoma cell lines. Overexpression of syndecan-2 enhanced migration and invasion of melanoma cells, whereas the opposite was observed when syndecan-2 levels were knocked down using small inhibitory RNAs. Syndecan-2 expression was enhanced by fibroblast growth factor-2, which is known to stimulate melanoma cell migration; however, alpha-melanocyte-stimulating hormone decreased syndecan-2 expression and melanoma cell migration and invasion in a melanin synthesis-independent manner. Furthermore, syndecan-2 overexpression rescued the migration defects induced by alpha-melanocyte-stimulating hormone treatment. Together, these data strongly suggest that syndecan-2 plays a crucial role in the migratory potential of melanoma cells.

Dissociating neural signatures of mental state retrodiction and classification based on facial expressions.

Posed facial expressions of actors have often been used as stimuli to induce mental state inferences, in order to investigate 'Theory of Mind' processes. However, such stimuli make it difficult to determine whether perceivers are using a basic or more elaborated mentalizing strategy. The current study used as stimuli covert recordings of target individuals who viewed various emotional expressions, which caused them to spontaneously mimic these expressions. Perceivers subsequently judged these subtle emotional expressions of the targets: in one condition ('classification') participants were instructed to classify the target's expression (i.e. match it to a sample) and in another condition ('retrodicting') participants were instructed to retrodict (i.e. infer which emotional expression the target was viewing). When instructed to classify, participants showed more prevalent activations in event-related brain potentials (ERPs) at earlier and mid-latency ERP components N170, P200 and P300-600. By contrast, when instructed to retrodict participants showed enhanced late frontal and fronto-temporal ERPs (N800-1000), with more sustained activity over the right than the left hemisphere. These findings reveal different cortical processes involved when retrodicting about a facial expression compared to merely classifying it, despite comparable performance on the behavioral task.

Methane production from horse manure and stall waste with softwood bedding.

Substantial stall waste is generated from horses on softwood bedding. The methane potential (G(pot)) of horse manure and constructed mixtures of stall waste with softwood bedding was determined at 35°C. G(pot) of 68, 191 and 273 mL/g volatile solids (VS) were estimated for three separate batches of horse manure, indicating variability in the material. Cumulative energy production over 20-40 days ranged from 3.11 ± 0.92 to 8.45 ± 5.42 × 10(5)kJ/metric ton wet weight horse manure alone, and from 1.69 ± 0.39 to 3.91 ± 0.47 × 10(5)kJ/metric ton wet weight horse manure plus softwood stall bedding (mixed at a 1:1 ratio on a VS basis). Softwood bedding was barely degradable and diluted the energy production of the stall waste; however, it did not cause inhibition of methane production from manure. Manually separated used softwood bedding contained substantial methane potential.