Explore with Me: Peer Observation Decreases Risk-Taking but Increases Exploration Tendencies across Adolescence.

It has been assumed that adolescents increase risk-taking tendencies when peers are present but findings on experimental decision-making have been inconclusive. Most studies focus on risk-taking tendencies, ignoring the effects peer presence can exert over other cognitive processes involved in decision-making, as well as any other underlying developmental and individual differences. In the present study, the trial-by-trial choice behavior was analyzed in a task in which adolescents adjust to dynamically changing risk probabilities. Using Bayesian modeling, the study aimed to infer about peer presence effects on risk-taking tendencies but also on reactions to, exploration of, and learning from positive and negative outcomes of risk-taking. 184 pre- to late adolescents (M = 14.09 years, min = 8.59, max = 18.97, SD = 2.95, 47% female) conducted the Balloon Analog Risk Task under two conditions: Once alone and once in the presence of a (non-existent) peer observing them virtually. Findings revealed that (a) peer observation reduced risk-taking but increased exploration tendencies and (b) that individual differences modulated this effect. Especially female pre-adolescents increased their openness to explore different choice outcomes when a peer observed their behavior. These results support the assumption that the occurrence and direction of peer influences on risk-taking depend on a person-environment interaction, emphasizing the dynamic role peers play in adolescent risk-taking.

Interactive extraction of diverse vocal units from a planar embedding without the need for prior sound segmentation.

Annotating and proofreading data sets of complex natural behaviors such as vocalizations are tedious tasks because instances of a given behavior need to be correctly segmented from background noise and must be classified with minimal false positive error rate. Low-dimensional embeddings have proven very useful for this task because they can provide a visual overview of a data set in which distinct behaviors appear in different clusters. However, low-dimensional embeddings introduce errors because they fail to preserve distances; and embeddings represent only objects of fixed dimensionality, which conflicts with vocalizations that have variable dimensions stemming from their variable durations. To mitigate these issues, we introduce a semi-supervised, analytical method for simultaneous segmentation and clustering of vocalizations. We define a given vocalization type by specifying pairs of high-density regions in the embedding plane of sound spectrograms, one region associated with vocalization onsets and the other with offsets. We demonstrate our two-neighborhood (2N) extraction method on the task of clustering adult zebra finch vocalizations embedded with UMAP. We show that 2N extraction allows the identification of short and long vocal renditions from continuous data streams without initially committing to a particular segmentation of the data. Also, 2N extraction achieves much lower false positive error rate than comparable approaches based on a single defining region. Along with our method, we present a graphical user interface (GUI) for visualizing and annotating data.

Age differences in decision making under known risk: The role of working memory and impulsivity.

This study examined whether age differences in risky decision making are dependent on known probability and value of outcomes (i.e., the expected value [EV]), the valence of anticipated outcomes (gains or losses), and individual differences in working memory and impulsivity. We used a task that varied risk independently from EV so that taking risks could be advantageous or disadvantageous. Results indicated differential developmental courses for the sensitivity to EV and outcome valence from early to late adolescence. An increase in risk-advantageous but a decrease in risk-disadvantageous behavior was obtained between early-to-mid and late adolescence. All adolescents showed higher risky behavior when losses rather than gains were expected. Age differences in the sensitivity to EV were fully mediated by individual differences in working memory but not by self-reported impulsivity, suggesting that decision making under known risk is strongly limited by the maturation of cognitive control processes. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Undirected singing rate as a non-invasive tool for welfare monitoring in isolated male zebra finches.

Research on the songbird zebra finch (Taeniopygia guttata) has advanced our behavioral, hormonal, neuronal, and genetic understanding of vocal learning. However, little is known about the impact of typical experimental manipulations on the welfare of these birds. Here we explore whether the undirected singing rate can be used as an indicator of welfare. We tested this idea by performing a post hoc analysis of singing behavior in isolated male zebra finches subjected to interactive white noise, to surgery, or to tethering. We find that the latter two experimental manipulations transiently but reliably decreased singing rates. By contraposition, we infer that a high-sustained singing rate is suggestive of successful coping or improved welfare in these experiments. Our analysis across more than 300 days of song data suggests that a singing rate above a threshold of several hundred song motifs per day implies an absence of an acute stressor or a successful coping with stress. Because singing rate can be measured in a completely automatic fashion, its observation can help to reduce experimenter bias in welfare monitoring. Because singing rate measurements are non-invasive, we expect this study to contribute to the refinement of the current welfare monitoring tools in zebra finches.

Are Mid-Adolescents Prone to Risky Decisions? The Influence of Task Setting and Individual Differences in Temperament.

Recent developmental models assume a higher tendency to take risks in mid-adolescence, while the empirical evidence for this assumption is rather mixed. Most of the studies applied quite different tasks to measure risk-taking behavior and used a narrow age range. The main goal of the present study was to examine risk-taking behavior in four task settings, the Treasure Hunting Task (THT) in a gain and a loss domain, the Balloon Analogue Risk Task (BART), and the STOPLIGHT task. These task settings differ in affective task moderators, like descriptive vs. experienced outcomes, anticipation of gains vs. losses, static vs. dynamic risk presentation, and time pressure vs. no time pressure and were applied in a sample of 187 participants from age 9-18. Beneath age trends, we were interested in their association with individual differences in approach behavior, venturesomeness, impulsivity, and empathy above age, gender, and fluid intelligence. Our findings revealed that risk-taking behavior is only low to moderately correlated between the four task contexts, suggesting that they capture different aspects of risk-taking behavior. Accordingly, a mid-adolescent peak in risk propensity was only found under time pressure in the STOPLIGHT that was associated with higher impulsivity and empathy. In contrast, risky decisions decreased with increasing age in task settings, in which losses were anticipated (THT Loss), and this was associated with higher cognitive abilities. We found no age differences when gains were anticipated, neither in a static (THT Gain) nor in a dynamic task setting (BART). These findings clearly suggest the need to consider affective task moderators, as well as individual differences in temperament and cognitive abilities, in actual models about adolescent development.

Elusive Zintl Ions [µ-HSi4 ]3- and [Si5 ]2- in Liquid Ammonia: Protonation States, Sites, and Bonding Situation Evaluated by NMR and Theory.

The existence of [µ-HSi4 ]3- in liquid ammonia solutions is confirmed by 1 H and 29 Si NMR experiments. Both NMR and quantum chemical calculations reveal that the H atom bridges two Si atoms of the [Si4 ]4- cluster, contrary to the expectation that it is located at one vertex Si of the tetrahedron. The calculations also indicate that in the formation of [µ-HSi4 ]3- , protonation is driven by a high charge density and an increase of electron delocalization compared to [Si4 ]4- . Additionally, [Si5 ]2- was detected for the first time and characterized by NMR. Calculations show that it is resistant to protonation, owing to a strong charge delocalization, which is significantly reduced upon protonation. Thus, our methods reveal three silicides in liquid ammonia: unprotonated [Si5 ]2- , terminally protonated [HSi9 ]3- , and bridge-protonated [µ-HSi4 ]3- . The protonation trend can be roughly predicted by the difference in charge delocalization between the parent compound and the product, which can be finely tuned by the presence of counter ions in solution.

The Structure of [HSi9 ]3- in the Solid State and Its Unexpected Highly Dynamic Behavior in Solution.

We report on the first unambiguous detection of the elusive [HSi9 ]3- anion in solutions of liquid ammonia by various 29 Si and 1 H NMR experiments including chemical exchange saturation transfer (CEST). The characteristic multiplicity patterns of both the 29 Si and 1 H resonances together with CEST and a partially reduced 1 H,29 Si coupling constant indicate the presence of a highly dynamic Si8 entity and a Si-H moiety with slow proton hopping. Theoretical calculations corroborate both reorganization of Si8 on the picosecond timescale via low vibrational modes and proton hopping. In addition, in a single-crystal X-ray study of (K(DB[18]crown-6))(K([2.2.2]crypt))2 [HSi9 ]⋅8.5 NH3 , the H atom was unequivocally localized at one vertex of the basal square of the monocapped square-antiprismatic cluster. Thus experimental studies and theoretical considerations provide unprecedented insight into both the structure and the dynamic behavior of these cluster anions, which hitherto had been considered to be rigid.

The Influence of Different Kinds of Incentives on Decision-Making and Cognitive Control in Adolescent Development: A Review of Behavioral and Neuroscientific Studies.

A number of recent hypothetical models on adolescent development take a dual-systems perspective and propose an imbalance in the maturation of neural systems underlying reward-driven and control-related behavior. In particular, such models suggest that the relative dominance of the early emerging subcortical reward system over the later emerging prefrontal-guided control system leads to higher risk-taking and sensation-seeking behavior in mid-adolescents. Here, we will review recent empirical evidence from behavioral and neuroscientific studies examining interactions between these systems and showing that empirical evidence in support for the view of a higher sensitivity to rewards in mid-adolescents is rather mixed. One possible explanation for this may be the use of different kinds and amounts of incentives across studies. We will therefore include developmental studies comparing the differential influence of primary and secondary incentives, as well as those investigating within the class of secondary incentives the effects of monetary, cognitive, or social incentives. We hypothesized that the value of receiving sweets or sours, winning or losing small or large amounts of money, and being accepted or rejected from a peer group may also changes across development, and thereby might modulate age differences in decision-making and cognitive control. Our review revealed that although developmental studies directly comparing different kinds of incentives are rather scarce, results of various studies rather consistently showed only minor age differences in the impact of incentives on the behavioral level. In tendency, adolescents were more sensitive to higher amounts of incentives and larger uncertainty of receiving them, as well as to social incentives such as the presence of peers observing them. Electrophysiological studies showed that processing efficiency was enhanced during anticipation of incentives and receiving them, irrespective of incentive type. Again, we found no strong evidence for interactions with age across studies. Finally, functional brain imaging studies revealed evidence for overlapping brain regions activated during processing of primary and secondary incentives, as well as social and non-social incentives. Adolescents recruited similar reward-related and control-related brain regions as adults did, but to a different degree. Implications for future research will be discussed.

Serotonin Decreases the Gain of Visual Responses in Awake Macaque V1.

Serotonin, an important neuromodulator in the brain, is implicated in affective and cognitive functions. However, its role even for basic cortical processes is controversial. For example, in the mammalian primary visual cortex (V1), heterogenous serotonergic modulation has been observed in anesthetized animals. Here, we combined extracellular single-unit recordings with iontophoresis in awake animals. We examined the role of serotonin on well-defined tuning properties (orientation, spatial frequency, contrast, and size) in V1 of two male macaque monkeys. We find that in the awake macaque the modulatory effect of serotonin is surprisingly uniform: it causes a mainly multiplicative decrease of the visual responses and a slight increase in the stimulus-selective response latency. Moreover, serotonin neither systematically changes the selectivity or variability of the response, nor the interneuronal correlation unexplained by the stimulus ("noise-correlation"). The modulation by serotonin has qualitative similarities with that for a decrease in stimulus contrast, but differs quantitatively from decreasing contrast. It can be captured by a simple additive change to a threshold-linear spiking nonlinearity. Together, our results show that serotonin is well suited to control the response gain of neurons in V1 depending on the animal's behavioral or motivational context, complementing other known state-dependent gain-control mechanisms.SIGNIFICANCE STATEMENT Serotonin is an important neuromodulator in the brain and a major target for drugs used to treat psychiatric disorders. Nonetheless, surprisingly little is known about how it shapes information processing in sensory areas. Here we examined the serotonergic modulation of visual processing in the primary visual cortex of awake behaving macaque monkeys. We found that serotonin mainly decreased the gain of the visual responses, without systematically changing their selectivity, variability, or covariability. This identifies a simple computational function of serotonin for state-dependent sensory processing, depending on the animal's affective or motivational state.

Rubber hand illusion affects joint angle perception.

The Rubber Hand Illusion (RHI) is a well-established experimental paradigm. It has been shown that the RHI can affect hand location estimates, arm and hand motion towards goals, the subjective visual appearance of the own hand, and the feeling of body ownership. Several studies also indicate that the peri-hand space is partially remapped around the rubber hand. Nonetheless, the question remains if and to what extent the RHI can affect the perception of other body parts. In this study we ask if the RHI can alter the perception of the elbow joint. Participants had to adjust an angular representation on a screen according to their proprioceptive perception of their own elbow joint angle. The results show that the RHI does indeed alter the elbow joint estimation, increasing the agreement with the position and orientation of the artificial hand. Thus, the results show that the brain does not only adjust the perception of the hand in body-relative space, but it also modifies the perception of other body parts. In conclusion, we propose that the brain continuously strives to maintain a consistent internal body image and that this image can be influenced by the available sensory information sources, which are mediated and mapped onto each other by means of a postural, kinematic body model.

Coating of titanium implants with copolymer supports bone regeneration: a comparative in vivo study in rabbits.

PURPOSE: In modern orthopedics aseptic loosening caused by the formation of micro-wear particles remains a problem for endoprosthetic joint replacements as revision surgery is necessary with corresponding costs and exertions by patients. This study is devoted to the question of how the osseous ingrowth of implants can be supported. It was investigated whether the developed copolymer, p-VBP-co-GMA, coated on the surface of the implants, supports bone healing. In addition, it was analyzed whether covalent linkage of Bone Morphogenetic Protein 2 (BMP-2) to the copolymer layer enhances bone formation. METHODS: Eight adult New Zealand White Rabbits were implanted with four different foils (control, copolymer, copolymer + BMP-2, control + BMP-2) each. The histomorphometric analysis of all samples was made 28 days after implantation. RESULTS: The copolymer had a positive effect on bone remodeling compared to the control group. We observed that the copolymer group had a significantly increased bone volume per tissue volume ratio and bone density to the control group. In contrast, this in-vivo study showed that the immobilization of BMP-2 onto the copolymer layer did not enhance bone healing. The bone volume per tissue volume ratio was decreased as well as the bone density compared to control + BMP-2 group. CONCLUSION: The analysis showed that the bone remodeling process in the copolymer + BMP-2-group is in an early phase comparable to the control group. These results suggest that the coating with the developed copolymer has major potential for medical use as it enhances bone mass around the implant.

Osseointegration by bone morphogenetic protein-2 and transforming growth factor beta2 coated titanium implants in femora of New Zealand white rabbits.

BACKGROUND: Intramembranous bone formation is essential in uncemented joint replacement to provide a mechanical anchorage of the implant. Since the discovery of bone morphogenic proteins (BMPs) by Urist in 1965, many studies have been conducted to show the influence of growth factors on implant ingrowth. In this study, the influence of bone morphogenetic protein-2 (rhBMP-2) and transforming growth factor ß2 (TGF-ß2) on implant osseointegration was investigated. MATERIALS AND METHODS: Thirty-two titanium cylinders were implanted into the femoral condyles of both hind legs of New Zealand White Rabbits. Four experimental groups were investigated: controls without coating, a macromolecular copolymer + covalently bound BMP-2, adsorbed BMP-2, and absorbed BMP-2+TGF-ß2. All samples were analyzed by ex vivo high-resolution micro-computed-tomography after 28 days of healing. Bone volume per total volume (BV/TV) was recorded around each implant. Afterward, all samples were biomechanically tested in a pull-out setup. RESULTS: The highest BV/TV ratio was seen in the BMP-2 group, followed by the BMP-2+TGF-ß2 group in high-resolution micro-computed-tomography. These groups were significantly different compared to the control group (P < 0.05). Copolymer+BMP-2 showed no significant difference in comparison to controls. In the pull-out setup, all groups showed higher fixation strength compared to the control group; these differences were not significant. CONCLUSIONS: No differences between BMP-2 alone and a combination of BMP-2+TGF-ß2 could be seen in the present study. However, the results of this study confirm the results of other studies that a coating with growth factors is able to enhance bone implant ingrowth. This may be of importance in defect situations during revision surgery to support the implant ingrowth and implant anchorage.

Coating of titanium implant materials with thin polymeric films for binding the signaling protein BMP2.

A fast and simple approach for immobilization using copolymers as interlayers is reported. The synthesized copolymers form stable self-assembled layers on implant materials like, e.g., titanium in a simple coating/drying/washing sequence and have functional groups which can bind proteins from an aqueous solution. The copolymer films have been characterized via ellipsometry and contact angle measurements and were tested for biocompatibility. An immunoassay was used to determine the amount of BMP2 and demonstrated an approximately 10-fold increase as compared to previously used self-assembled monolayers. A BMP2-responsive cell line with luciferase detection was used to determine the biological activity of the bound signaling protein.

Enhancement of endoprosthesis anchoring using BMP-2.

Osseointegration of long-term implants is still a problem in orthopaedic surgery. In recent years, several techniques to modify the implant surface to increase bone formation around implants have been described by many authors. Most endoprostheses used in orthopaedic surgery are manufactured from titanium. To understand the process of osseointegration, one has to take into account, that the adhesion of plasma proteins on the surface of titanium implants plays an essential role in the process of implant integration. In the last years, several modifications of implant surfaces (structure, chemistry, surface charge, wettability) have been investigated to improve osseointegration of titanium implants. Furthermore, several cytokines and growth factors have also been suggested to stimulate an implant ingrowth. In this respect, functionalized titanium implant surfaces with bone morphogenetic proteins-2 (BMP-2) as one particular member of the superfamily of transforming growth factor beta (TGF-beta), have proven a potential to stimulate bone formation around implants in different species. In this review the authors provide an overview of surface coatings with BMP-2 and their use in laboratory and experimental settings.