Somppi Sanni, Törnqvist Heini, Topál József, Koskela Aija, Hänninen Laura, Krause Christina M, Vainio Outi
Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
Institute of Cognitive Neuroscience and Psychology, Hungarian Academy of Sciences, Budapest, Hungary.
Front Psychol. 2017 Oct 17;8:1854. doi: 10.3389/fpsyg.2017.01854. eCollection 2017.
The neuropeptide oxytocin plays a critical role in social behavior and emotion regulation in mammals. The aim of this study was to explore how nasal oxytocin administration affects gazing behavior during emotional perception in domestic dogs. Looking patterns of dogs, as a measure of voluntary attention, were recorded during the viewing of human facial expression photographs. The pupil diameters of dogs were also measured as a physiological index of emotional arousal. In a placebo-controlled within-subjects experimental design, 43 dogs, after having received either oxytocin or placebo (saline) nasal spray treatment, were presented with pictures of unfamiliar male human faces displaying either a happy or an angry expression. We found that, depending on the facial expression, the dogs' gaze patterns were affected selectively by oxytocin treatment. After receiving oxytocin, dogs fixated less often on the eye regions of angry faces and revisited (glanced back at) more often the eye regions of smiling (happy) faces than after the placebo treatment. Furthermore, following the oxytocin treatment dogs fixated and revisited the eyes of happy faces significantly more often than the eyes of angry faces. The analysis of dogs' pupil diameters during viewing of human facial expressions indicated that oxytocin may also have a modulatory effect on dogs' emotional arousal. While subjects' pupil sizes were significantly larger when viewing angry faces than happy faces in the control (placebo treatment) condition, oxytocin treatment not only eliminated this effect but caused an opposite pupil response. Overall, these findings suggest that nasal oxytocin administration selectively changes the allocation of attention and emotional arousal in domestic dogs. Oxytocin has the potential to decrease vigilance toward threatening social stimuli and increase the salience of positive social stimuli thus making eye gaze of friendly human faces more salient for dogs. Our study provides further support for the role of the oxytocinergic system in the social perception abilities of domestic dogs. We propose that oxytocin modulates fundamental emotional processing in dogs through a mechanism that may facilitate communication between humans and dogs.
神经肽催产素在哺乳动物的社会行为和情绪调节中起着关键作用。本研究的目的是探讨经鼻腔给予催产素如何影响家犬在情绪感知过程中的注视行为。在观看人类面部表情照片时，记录家犬的注视模式，以此作为自主注意力的一种衡量方式。还测量了家犬的瞳孔直径，作为情绪唤起的生理指标。在一项安慰剂对照的被试内实验设计中，43只家犬在接受催产素或安慰剂（生理盐水）鼻腔喷雾治疗后，观看展示开心或愤怒表情的陌生男性人脸图片。我们发现，根据面部表情的不同，家犬的注视模式受到催产素治疗的选择性影响。接受催产素后，与接受安慰剂治疗相比，家犬较少注视愤怒面孔的眼睛区域，而更多地回看（再次看向）微笑（开心）面孔的眼睛区域。此外，接受催产素治疗后，家犬注视和回看开心面孔眼睛的频率显著高于愤怒面孔的眼睛。对家犬观看人类面部表情时瞳孔直径的分析表明，催产素可能也对家犬的情绪唤起有调节作用。在对照（安慰剂治疗）条件下，被试观看愤怒面孔时的瞳孔尺寸显著大于观看开心面孔时的瞳孔尺寸，而催产素治疗不仅消除了这种效应，还引起了相反的瞳孔反应。总体而言，这些发现表明经鼻腔给予催产素会选择性地改变家犬的注意力分配和情绪唤起。催产素有可能降低对威胁性社会刺激的警惕性，并增加积极社会刺激的显著性，从而使友好人类面孔的目光对视对家犬更具显著性。我们的研究为催产素能系统在家犬社会感知能力中的作用提供了进一步支持。我们提出，催产素通过一种可能促进人与犬之间交流的机制来调节犬的基本情绪处理。
