Tracking eye-movements provides easy access to cognitive processes involved in visual and sensorimotor processing. More recently, the underlying neural mechanisms have been examined by combining ...eye-tracking and functional neuroimaging methods. Apart from extracting visual information, gaze also serves important functions in social interactions. As a deictic cue, gaze can be used to direct the attention of another person to an object. Conversely, by following other persons' gaze we gain access to their attentional focus, which is essential for understanding their mental states. Social gaze has therefore been studied extensively to understand the social brain. In this endeavor, gaze has mostly been investigated from an observational perspective using static displays of faces and eyes. However, there is growing consent that observational paradigms are insufficient for an understanding of the neural mechanisms of social gaze behavior, which typically involve active engagement in social interactions. Recent methodological advances have allowed increasing ecological validity by studying gaze in face-to-face encounters in real-time. Such improvements include interactions using virtual agents in gaze-contingent eye-tracking paradigms, live interactions via video feeds, and dual eye-tracking in two-person setups. These novel approaches can be used to analyze brain activity related to social gaze behavior. This review introduces these methodologies and discusses recent findings on the behavioral functions and neural mechanisms of gaze processing in social interaction.
There is ample evidence that human primates strive for social contact and experience interactions with conspecifics as intrinsically rewarding. Focusing on gaze behavior as a crucial means of human ...interaction, this study employed a unique combination of neuroimaging, eye-tracking, and computer-animated virtual agents to assess the neural mechanisms underlying this component of behavior. In the interaction task, participants believed that during each interaction the agent's gaze behavior could either be controlled by another participant or by a computer program. Their task was to indicate whether they experienced a given interaction as an interaction with another human participant or the computer program based on the agent's reaction. Unbeknownst to them, the agent was always controlled by a computer to enable a systematic manipulation of gaze reactions by varying the degree to which the agent engaged in joint attention. This allowed creating a tool to distinguish neural activity underlying the subjective experience of being engaged in social and non-social interaction. In contrast to previous research, this allows measuring neural activity while participants experience active engagement in real-time social interactions. Results demonstrate that gaze-based interactions with a perceived human partner are associated with activity in the ventral striatum, a core component of reward-related neurocircuitry. In contrast, interactions with a computer-driven agent activate attention networks. Comparisons of neural activity during interaction with behaviorally naïve and explicitly cooperative partners demonstrate different temporal dynamics of the reward system and indicate that the mere experience of engagement in social interaction is sufficient to recruit this system.
•Gaze-based social interaction in real-time was studied using virtual reality tools.•The subjective experience of human social interaction recruited the reward system.•Orbitofrontal and striatal activity was modulated by the interaction context.•Explicit cooperation altered the neural integration of gaze reactions.
In social interaction, gaze behavior provides important signals that have a significant impact on our perception of others. Previous investigations, however, have relied on paradigms in which ...participants are passive observers of other persons' gazes and do not adjust their gaze behavior as is the case in real-life social encounters. We used an interactive eye-tracking paradigm that allows participants to interact with an anthropomorphic virtual character whose gaze behavior is responsive to where the participant looks on the stimulus screen in real time. The character's gaze reactions were systematically varied along a continuum from a maximal probability of gaze aversion to a maximal probability of gaze-following during brief interactions, thereby varying contingency and congruency of the reactions. We investigated how these variations influenced whether participants believed that the character was controlled by another person (i.e., a confederate) or a computer program. In a series of experiments, the human confederate was either introduced as naïve to the task, cooperative, or competitive. Results demonstrate that the ascription of humanness increases with higher congruency of gaze reactions when participants are interacting with a naïve partner. In contrast, humanness ascription is driven by the degree of contingency irrespective of congruency when the confederate was introduced as cooperative. Conversely, during interaction with a competitive confederate, judgments were neither based on congruency nor on contingency. These results offer important insights into what renders the experience of an interaction truly social: Humans appear to have a default expectation of reciprocation that can be influenced drastically by the presumed disposition of the interactor to either cooperate or compete.
In order to evaluate the complications and risk factors associated with peripheral arterial catheters used for haemodynamic monitoring, we reviewed the literature published from 1978 to 2001. We ...closely examined the three most commonly used arterial cannulation sites. The reviewed papers included a total of 19,617 radial, 3899 femoral and 1989 axillary artery catheterizations. Factors that contribute to higher complication rates were investigated. Major complications occurred in fewer than 1% of the cases, and rates were similar for the radial, femoral and axillary arteries. We conclude that arterial cannulation is a safe procedure.
BACKGROUND
Nucleic acid–targeted pathogen inactivation technology using amustaline (S‐303) and glutathione (GSH) was developed to reduce the risk of transfusion‐transmitted infectious disease and ...transfusion‐associated graft‐versus‐host disease with red blood cell (RBC) transfusion.
STUDY DESIGN AND METHODS
A randomized, double‐blind, controlled study was performed to assess the in vitro characteristics of amustaline‐treated RBCs (test) compared with conventional (control) RBCs and to evaluate safety and efficacy of transfusion during and after cardiac surgery. The primary device efficacy endpoint was the postproduction hemoglobin (Hb) content of RBCs. Exploratory clinical outcomes included renal and hepatic failure, the 6‐minute walk test (a surrogate for cardiopulmonary function), adverse events (AEs), and the immune response to amustaline‐treated RBCs.
RESULTS
A total of 774 RBC unis were produced. Mean treatment difference in Hb content was –2.27 g/unit (95% confidence interval, –2.61 to –1.92 g/unit), within the prespecified equivalence margins (±5 g/unit) to declare noninferiority. Amustaline‐treated RBCs met European guidelines for Hb content, hematocrit, and hemolysis. Fifty‐one (25 test and 26 control) patients received study RBCs. There were no significant differences in RBC usage or other clinical outcomes. Observed AEs were within the spectrum expected for patients of similar age undergoing cardiovascular surgery requiring RBCs transfusion. No patients exhibited an immune response specific to amustaline‐treated RBCs.
CONCLUSION
Amustaline‐treated RBCs demonstrated equivalence to control RBCs for Hb content, have appropriate characteristics for transfusion, and were well tolerated when transfused in support of acute anemia. Renal impairment was characterized as a potential efficacy endpoint for pivotal studies of RBC transfusion in cardiac surgery.
To compare noninvasive pulse-pressure variation (PPV) measurements obtained from a new high-fidelity upper arm cuff using a hydraulic coupling technique to corresponding intraarterial PPV ...measurements.
The authors used prospective multicenter comparison and development studies for the new high-fidelity upper arm cuff.
The study was performed in the departments of Anesthesiology at the Ludwig-Maximilians-Universität München Hospital, the University Hospital of Bonn, and the RoMed Hospital in Rosenheim (all Germany).
A total of 153 patients were enrolled, undergoing major abdominal surgery or neurosurgery with mechanical ventilation. For the evaluation of PPV, 1,467 paired measurements in 107 patients were available after exclusion due to predefined quality criteria.
Simultaneous measurements of PPV were performed from a reference femoral arterial catheter (PPVref) and the high-fidelity upper arm cuff (PPVcuff). The new device uses a semirigid conical shell. It incorporates a hydraulic sensor pad with a pressure transducer, leading to a tissue pressure-pulse contour with all characteristics of an arterial- pulse contour.
The comparative analysis of the included measurements showed that PPVref and PPVcuff were closely correlated (r = 0.92). The mean of the differences between PPVref and PPVcuff was 0.1 ± 2.0%, with 95% limits of agreement between –4.1% and 3.9%. To track absolute changes in PPV >2%, the concordance rate between the 2 methods was 93%.
The new high-fidelity upper arm cuff method provided a clinically reliable estimate of PPV.
Emotional facial expressions provide important nonverbal cues in human interactions. The perception of emotions is not only influenced by a person's ethnic background but also depends on whether a ...person is engaged with the emotion-encoder. Although these factors are known to affect emotion perception, their impact has only been studied in isolation before. The aim of the present study was to investigate their combined influence. Thus, in order to study the influence of engagement on emotion perception between persons from different ethnicities, we compared participants from China and Germany. Asian-looking and European-looking virtual agents expressed anger and happiness while gazing at the participant or at another person. Participants had to assess the perceived valence of the emotional expressions. Results indicate that indeed two factors that are known to have a considerable influence on emotion perception interacted in their combined influence: We found that the perceived intensity of an emotion expressed by ethnic in-group members was in most cases independent of gaze direction, whereas gaze direction had an influence on the emotion perception of ethnic out-group members. Additionally, participants from the ethnic out-group tended to perceive emotions as more pronounced than participants from the ethnic in-group when they were directly gazed at. These findings suggest that gaze direction has a differential influence on ethnic in-group and ethnic out-group dynamics during emotion perception.
A study by Ernst Fehr and colleagues (Kosfeld et al., 2005), in which the intranasal administration of oxytocin increased the trusting behavior of investors toward strangers in an economic trust ...game, triggered a growing body of studies demonstrating a plethora of positive effects of oxytocin on social behaviors. The gist of the media coverage of oxytocin is that the molecular substrate of good and evil has finally been discovered and that a sniff of this substance might be sufficient to restore love, understanding, and peace in the world. ...oxytocin leads to in-group favoritism and results in non-cooperative, defective and even aggressive behavior toward out-group members (De Dreu, 2012).
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