Laughter is a universal human behavior generated by the cooperation of different systems toward the construction of an expressive vocal pattern. Given the sensitivity of neuroimaging techniques to movements, the neural mechanisms underlying laughter expression remain unclear. Herein, we characterized the neural correlates of emotional laughter using the onsets and the duration of laughter bursts to inform functional magnetic resonance imaging. Laughter-related blood oxygen level-dependent (BOLD) increases involved both the motor (motor cortex, supplementary motor area, frontal operculum) and the emotional/limbic (anterior cingulate cortex, amygdala, n. accumbens, hippocampus) systems, as well as modulatory circuitries encompassing the basal ganglia, thalamus, and cerebellum. BOLD changes related to the 2 s preceding the laughter outbreak were selectively observed at the temporo-occipital junction and the periaqueductal gray matter, supporting the role of the former in the detection of incongruity and the gating role of the latter in the initiation of spontaneous laughter. Moreover, developmental changes were identified in laughter processing, consisting in a greater engagement of the reward circuitry in younger subjects; conversely, the default mode network appears more activated in older participants. Our findings contribute valuable information about the processing of real-life humorous materials and suggest a close link between laughter-related motor, affective, and cognitive elements, confirming its complex and multi-faceted nature.

中文翻译：

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运动和边缘系统对整个生命周期的情绪笑声的贡献。

笑是一种普遍的人类行为，是由不同系统合作构建富有表现力的声音模式而产生的。鉴于神经影像技术对运动的敏感性，笑声表达背后的神经机制仍不清楚。在此，我们使用爆发性笑声的开始和持续时间来表征情绪性笑声的神经相关性，以告知功能性磁共振成像。与笑声相关的血氧水平依赖性 (BOLD) 增加涉及运动（运动皮层、辅助运动区、额叶盖）和情绪/边缘（前扣带回皮层、杏仁核、伏隔核、海马）系统，以及调节回路包括基底神经节、丘脑和小脑。在颞枕交界处和导水管周围灰质处选择性地观察到与笑声爆发前 2 s 相关的 BOLD 变化，支持前者在检测不协调中的作用和后者在自发性笑声开始中的门控作用. 此外，在笑声处理中发现了发展变化，包括在年轻受试者中更多地参与奖励回路；相反，默认模式网络在年长的参与者中显得更加活跃。我们的研究结果提供了有关处理现实生活幽默材料的宝贵信息，并表明与笑声相关的运动、情感和认知元素之间存在密切联系，证实了其复杂和多方面的性质。