Anatomy and Program in Neuroscience, Department of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland.
Cereb Cortex. 2013 Jun;23(6):1280-9. doi: 10.1093/cercor/bhs094. Epub 2012 Apr 16.
The burst of laughter that is evoked by tickling is a primitive form of vocalization. It evolves during an early phase of postnatal life and appears to be independent of higher cortical circuits. Clinicopathological observations have led to suspicions that the hypothalamus is directly involved in the production of laughter. In this functional magnetic resonance imaging investigation, healthy participants were 1) tickled on the sole of the right foot with permission to laugh, 2) tickled but asked to stifle laughter, and 3) requested to laugh voluntarily. Tickling that was accompanied by involuntary laughter activated regions in the lateral hypothalamus, parietal operculum, amygdala, and right cerebellum to a consistently greater degree than did the 2 other conditions. Activation of the periaqueductal gray matter was observed during voluntary and involuntary laughter but not when laughter was inhibited. The present findings indicate that hypothalamic activity plays a crucial role in evoking ticklish laughter in healthy individuals. The hypothalamus promotes innate behavioral reactions to stimuli and sends projections to the periaqueductal gray matter, which is itself an important integrative center for the control of vocalization. A comparison of our findings with published data relating to humorous laughter revealed the involvement of a common set of subcortical centers.
被挠痒时引发的笑声是一种原始的发声形式。它在出生后的早期阶段发展，并似乎独立于高级皮质回路。临床病理观察使人们怀疑下丘脑直接参与了笑声的产生。在这项功能性磁共振成像研究中，健康参与者 1）被允许发笑时，右脚底被挠痒，2）被挠痒但要求忍住笑，3）自愿发笑。与其他两种情况相比，伴随着不由自主的笑声的挠痒会更强烈地激活外侧下丘脑、顶叶脑回、杏仁核和右侧小脑的区域。在自愿和不由自主的笑声时观察到了导水管周围灰质的激活，但在抑制笑声时则没有。这些发现表明，下丘脑活动在健康个体中引发瘙痒的笑声中起着至关重要的作用。下丘脑促进对刺激的先天行为反应，并向导水管周围灰质发送投射，而导水管周围灰质本身就是控制发声的重要整合中心。我们的发现与涉及幽默笑声的已发表数据进行比较，揭示了一组共同的皮质下中心的参与。
