Reports on the modulatory role of the neuropeptide oxytocin on social cognition and behavior have steadily increased over the last two decades, stimulating considerable interest in its psychiatric application. Basic and clinical research in humans primarily employs intranasal application protocols. This approach assumes that intranasal administration increases oxytocin levels in the central nervous system via a direct nose-to-brain route, which in turn acts upon centrally-located oxytocin receptors to exert its behavioral effects. However, debates have emerged on whether intranasally administered oxytocin enters the brain via the nose-to-brain route and whether this route leads to functionally relevant increases in central oxytocin levels. In this review we outline recent advances from human and animal research that provide converging evidence for functionally relevant effects of the intranasal oxytocin administration route, suggesting that direct nose-to-brain delivery underlies the behavioral effects of oxytocin on social cognition and behavior. Moreover, advances in previously debated methodological issues, such as pre-registration, reproducibility, statistical power, interpretation of non-significant results, dosage, and sex differences are discussed and integrated with suggestions for the next steps in translating intranasal oxytocin into psychiatric applications.
The results suggest that OT increased covert attention to happy faces, thereby supporting the hypothesis that OT modulates early attentional processes that might promote prosocial behavior.
To investigate the mechanisms by which oxytocin improves socioaffective processing, we measured behavioral and pupillometric data during a dynamic facial emotion recognition task. In a double-blind between-subjects design, 47 men received either 24 IU intranasal oxytocin (OXT) or a placebo (PLC). Participants in the OXT group recognized all facial expressions at lower intensity levels than did participants in the PLC group. Improved performance was accompanied by increased task-related pupil dilation, indicating an increased recruitment of attentional resources. We also found increased pupil dilation during the processing of female compared with male faces. This gender-specific stimulus effect diminished in the OXT group, in which pupil size specifically increased for male faces. Results suggest that improved emotion recognition after OXT treatment might be due to an intensified processing of stimuli that usually do not recruit much attention.
This article presents GazeAlyze, a software package, written as a MATLAB (MathWorks Inc., Natick, MA) toolbox developed for the analysis of eye movement data. GazeAlyze was developed for the batch processing of multiple data files and was designed as a framework with extendable modules. GazeAlyze encompasses the main functions of the entire processing queue of eye movement data to static visual stimuli. This includes detecting and filtering artifacts, detecting events, generating regions of interest, generating spread sheets for further statistical analysis, and providing methods for the visualization of results, such as path plots and fixation heat maps. All functions can be controlled through graphical user interfaces. GazeAlyze includes functions for correcting eye movement data for the displacement of the head relative to the camera after calibration in fixed head mounts. The preprocessing and event detection methods in GazeAlyze are based on the software ILAB 3.6.8 Gitelman (Behav Res Methods Instrum Comput 34(4), 605-612, 2002). GazeAlyze is distributed free of charge under the terms of the GNU public license and allows code modifications to be made so that the program's performance can be adjusted according to a user's scientific requirements.
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