Caruana F, Gozzo F, Pelliccia V, Cossu M, Avanzini P
Department of Neuroscience, University of Parma, Parma, Italy; CNR Institute of Neuroscience, Parma, Italy.
Claudio Munari Center for Epilepsy Surgery, ASST Grande Ospedale Metropolitano Niguarda, Milan, Italy.
Neuropsychologia. 2016 Aug;89:364-370. doi: 10.1016/j.neuropsychologia.2016.07.001. Epub 2016 Jul 9.
Laughter and smile are typical expressions of mirth and fundamental means of social communication. Despite their general interest, the current knowledge about the brain regions involved in the production of these expressions is still very limited, and the principal insights come from electrical stimulation (ES) studies in patients, in which, nevertheless, laughter or smile have been elicited very rarely. Previous studies showed that laughter is evoked by the stimulation of nodes of an emotional network encompassing the anterior cingulate, the superior frontal and basal temporal cortex. A common feature of these stimulation studies is that the facial expression was always accompanied by motor awareness and often by mirth, in line with the affective functions attributed to these regions. Little is known, in contrast, on the neural basis of the voluntary motor control of this expression. The objective of this study was to investigate the effect of ES of the frontal operculum (FO), which is considered a crucial node for the linkage of the voluntary motor system for emotional expression and limbic emotional network. We report the case of ES applied to the frontal operculum (FO) in four patients with drug-resistant focal epilepsy undergoing stereo-electroencephalographic (SEEG) implantation of intracerebral electrodes. In all patients, ES applied to the FO produced laughter or smile. Interestingly, in one patient, the production of a smiling expression was also clearly accompanied by the lack of motor awareness. Since the lack of motor awareness has been previously observed only after the stimulation of the voluntary motor network, we speculate that FO is involved in the voluntary control of facial expressions, and is placed at the interface with the emotional network, gating limbic information to the motor system.
笑和微笑是愉悦的典型表现，也是社交沟通的基本方式。尽管它们备受关注，但目前对于参与这些表情产生的脑区的了解仍然非常有限，主要的见解来自对患者的电刺激（ES）研究，然而，在这些研究中，很少诱发笑或微笑。先前的研究表明，刺激包含前扣带回、额上回和颞叶基底皮质的情感网络节点会诱发笑。这些刺激研究的一个共同特征是，面部表情总是伴随着运动意识，并且常常伴随着愉悦，这与归因于这些区域的情感功能一致。相比之下，对于这种表情的自主运动控制的神经基础知之甚少。本研究的目的是调查额盖（FO）的电刺激的效果，额盖被认为是情感表达的自主运动系统与边缘情感网络联系的关键节点。我们报告了4例耐药性局灶性癫痫患者在接受脑内电极立体定向脑电图（SEEG）植入时，对额盖（FO）进行电刺激的病例。在所有患者中，对FO进行电刺激都产生了笑或微笑。有趣的是，在一名患者中，微笑表情的产生也明显伴随着运动意识的缺失。由于之前仅在刺激自主运动网络后才观察到运动意识的缺失，我们推测FO参与了面部表情的自主控制，并处于与情感网络的接口处，将边缘信息传递给运动系统。
