Bertaccini Riccardo, Ippolito Giuseppe, Tarasi Luca, Zazio Agnese, Stango Antonietta, Bortoletto Marta, Romei Vincenzo
Centro Studi e Ricerche in Neuroscienze Cognitive, Dipartimento di Psicologia, Alma Mater Studiorum-Università di Bologna, 47521 Cesena, Italy.
Neurophysiology Lab., IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy.
Biomedicines. 2023 Jun 17;11(6):1746. doi: 10.3390/biomedicines11061746.
Multisensory integration is quintessential to adaptive behavior, with clinical populations showing significant impairments in this domain, most notably hallucinatory reports. Interestingly, altered cross-modal interactions have also been reported in healthy individuals when engaged in tasks such as the Sound-Induced Flash-Illusion (SIFI). The temporal dynamics of the SIFI have been recently tied to the speed of occipital alpha rhythms (IAF), with faster oscillations entailing reduced temporal windows within which the illusion is experienced. In this regard, entrainment-based protocols have not yet implemented rhythmic transcranial magnetic stimulation (rhTMS) to causally test for this relationship. It thus remains to be evaluated whether rhTMS-induced acoustic and somatosensory sensations may not specifically interfere with the illusion. Here, we addressed this issue by asking 27 volunteers to perform a SIFI paradigm under different Sham and active rhTMS protocols, delivered over the occipital pole at the IAF. Although TMS has been proven to act upon brain tissues excitability, results show that the SIFI occurred for both Sham and active rhTMS, with the illusory rate not being significantly different between baseline and stimulation conditions. This aligns with the discrete sampling hypothesis, for which alpha amplitude modulation, known to reflect changes in cortical excitability, should not account for changes in the illusory rate. Moreover, these findings highlight the viability of rhTMS-based interventions as a means to probe the neuroelectric signatures of illusory and hallucinatory audiovisual experiences, in healthy and neuropsychiatric populations.
多感官整合对于适应性行为至关重要，临床人群在这一领域表现出显著损伤，最明显的是幻觉报告。有趣的是，在健康个体中，当参与诸如声音诱发闪光错觉（SIFI）等任务时，也有跨模态交互改变的报道。SIFI的时间动态最近与枕叶阿尔法节律（IAF）的速度相关，振荡越快，产生错觉的时间窗口就越小。在这方面，基于夹带的方案尚未实施节律性经颅磁刺激（rhTMS）来因果性地检验这种关系。因此，rhTMS诱发的听觉和体感是否不会特别干扰错觉仍有待评估。在这里，我们通过让27名志愿者在不同的假刺激和主动rhTMS方案下进行SIFI范式来解决这个问题，刺激在IAF的枕叶极上进行。尽管经颅磁刺激已被证明可作用于脑组织兴奋性，但结果表明，假刺激和主动rhTMS时均出现了SIFI，基线和刺激条件下的错觉率无显著差异。这与离散采样假说相符，即已知反映皮质兴奋性变化的阿尔法振幅调制不应解释错觉率的变化。此外，这些发现凸显了基于rhTMS的干预措施作为一种手段来探究健康人群和神经精神疾病人群中虚幻和幻觉视听体验的神经电特征的可行性。
