Department of Veterinary Sciences, University of Pisa, Pisa, Italy.
Research Center "E. Piaggio", University of Pisa, Pisa, Italy.
PLoS One. 2021 Aug 5;16(8):e0255688. doi: 10.1371/journal.pone.0255688. eCollection 2021.
Animals must attend to a diverse array of stimuli in their environments. The emotional valence and salience of a stimulus can affect how this information is processed in the brain. Many species preferentially attend to negatively valent stimuli using the sensory organs on the left side of their body and hence the right hemisphere of their brain. Here, we investigated the lateralisation of visual attention to the rapid appearance of a stimulus (an inflated balloon) designed to induce an avoidance reaction and a negatively valent emotional state in 77 Italian saddle horses. Horses' eyes are laterally positioned on the head, and each eye projects primarily to the contralateral hemisphere, allowing eye use to be a proxy for preferential processing in one hemisphere of the brain. We predicted that horses would inspect the novel and unexpected stimulus with their left eye and hence right hemisphere. We found that horses primarily inspected the balloon with one eye, and most horses had a preferred eye to do so, however, we did not find a population level tendency for this to be the left or the right eye. The strength of this preference tended to decrease over time, with the horses using their non-preferred eye to inspect the balloon increasingly as the trial progressed. Our results confirm a lateralised eye use tendency when viewing negatively emotionally valent stimuli in horses, in agreement with previous findings. However, there was not any alignment of lateralisation at the group level in our sample, suggesting that the expression of lateralisation in horses depends on the sample population and testing context.
动物在其环境中必须关注各种各样的刺激。刺激的情绪效价和显著性会影响大脑对这些信息的处理方式。许多物种会使用身体左侧的感觉器官，即大脑的右半球，优先关注负面效价的刺激。在这里，我们研究了 77 匹意大利 saddle 马对刺激（充气气球）快速出现的视觉注意力的侧化，该刺激旨在引起回避反应和负面情绪状态。马的眼睛在头部是侧向排列的，每只眼睛主要投射到对侧半球，因此眼睛的使用可以作为大脑一侧优先处理的替代指标。我们预测，马会用左眼（即右半球）观察新奇和意外的刺激。我们发现，马主要用一只眼睛观察气球，而且大多数马都有一只偏好的眼睛来观察，但我们没有发现这种偏好是左眼或右眼的群体倾向。随着时间的推移，这种偏好的强度会逐渐减弱，随着试验的进行，马会越来越多地用非偏好的眼睛观察气球。我们的结果证实了马在观看负面情绪效价刺激时存在侧化的眼睛使用倾向，这与之前的发现一致。然而，在我们的样本中，没有任何群体水平的侧化对齐，这表明马的侧化表达取决于样本群体和测试环境。
