Department of Veterinary Sciences, University of Pisa, Pisa, Italy.
Department of Agricultural and Food Sciences, University of Bologna, Bologna, Italy.
PLoS One. 2023 Aug 8;18(8):e0289753. doi: 10.1371/journal.pone.0289753. eCollection 2023.
Cerebral lateralisation is the tendency for an individual to preferentially use one side of their brain and is apparent in the biased use of paired sensory organs. Horses vary in eye use when viewing a novel stimulus which may be due to different physiological reactions. To understand the interplay between physiology and lateralisation, we presented a novel object (an inflated balloon) to 20 horses while electrocardiogram traces were collected. We measured the amount of time each horse looked at the balloon with each eye. We calculated 'sample entropy' as a measure of non-linear heart rate variability both prior to and during the stimulus presentation. A smaller drop in sample entropy values between the habituation phase and the sample presentation indicates the maintenance of a more complex signal associated with a relaxed physiological state. Horses that spent longer viewing the balloon with their left eye had a greater reduction in sample entropy, while time spend looking with the right eye was unrelated to the change in sample entropy. Therefore, the horses that exhibited a greater reduction in sample entropy tended to use their right hemisphere more, which may take precedence in emotional reactions. These results may help to explain the variation in lateralisation observed among horses.
大脑偏侧化是指个体倾向于优先使用大脑的一侧，这在双侧感觉器官的偏侧使用中表现明显。马在观察新刺激时，眼睛的使用方式存在差异，这可能是由于不同的生理反应所致。为了了解生理和偏侧化之间的相互作用，我们向 20 匹马展示了一个新物体（一个充气气球），同时记录心电图。我们测量了每匹马用每只眼睛看气球的时间。我们计算了“样本熵”，作为非线性心率变异性的度量，分别在刺激呈现前后进行测量。在习惯化阶段和样本呈现阶段之间，样本熵值下降幅度越小，表明与放松的生理状态相关的更复杂信号的维持。那些用左眼观察气球时间较长的马，样本熵的降幅更大，而用右眼观察的时间与样本熵的变化无关。因此，样本熵降幅较大的马往往更倾向于使用右脑，而右脑在情绪反应中可能占据主导地位。这些结果可能有助于解释马中观察到的偏侧化变化。
