Transcranial ultrasound stimulation in humans is associated with an auditory confound that can be effectively masked.
Transcranial ultrasound stimulation in humans is associated with an auditory confound that can be effectively masked.
复制标题
人类中的经颅超声刺激与可以有效掩盖的听觉混杂有关。
DOI：
10.1016/j.brs.2020.08.014
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发表时间：
2020-11
影响因子：
7.7
通讯作者：
Butler CR
中科院分区：
文献类型：
--
作者：
Braun V;Blackmore J;Cleveland RO;Butler CR
经颅超声刺激(TUS)是一种潜在的强大的、非侵入性的局部脑刺激技术。然而，最近的动物研究表明，TUS的效应可能会被早期听觉通路的间接刺激所混淆。我们的目标是在人类参与者中调查TUS是否会引起可听的声音，以及这些声音是否可以被音频信号掩盖。对18名健康受试者进行了T1加权磁共振脑成像，以进行三维超声模拟，以确定最佳换能器位置和震源幅度。热模拟确保了目标的温升为<；0.5℃，头骨的温升为<；3℃。为了测试非特异性听觉激活，对初级视觉皮质进行了TUS(500 GHz，300 ms脉冲，调制频率为1 GHz，占空比为50%)，并要求参与者区分刺激和非刺激试验。在整个任务过程中都记录了脑电。此外，体外头骨实验测试了TUS期间头骨振动的存在。我们发现，参与者在TUS过程中可以听到声音，并能够区分刺激和非刺激试验。这一点得到了脑电记录的证实，表明听觉激活与TUS有关。当使用TUS时，通过耳机向参与者传递音频波形，将检测率降低到Chance水平，并消除TUS诱导的听觉脑电信号。体外头骨实验证明，声音是以超声波的脉冲重复频率通过头骨传导的。未来在人类身上使用TUS的研究需要考虑到这种听觉混乱，并适当地屏蔽刺激。经颅超声刺激可在人体内产生听觉信号。健康的人类参与者可以区分刺激和非刺激试验。听觉掩蔽降低了检测率。颅骨振动是在经颅超声刺激过程中出现的。听觉信号可能是由于脉冲重复频率的骨传导造成的。
Transcranial ultrasound stimulation (TUS) is emerging as a potentially powerful, non-invasive technique for focal brain stimulation. Recent animal work suggests, however, that TUS effects may be confounded by indirect stimulation of early auditory pathways. We aimed to investigate in human participants whether TUS elicits audible sounds and if these can be masked by an audio signal. In 18 healthy participants, T1-weighted magnetic resonance brain imaging was acquired for 3D ultrasound simulations to determine optimal transducer placements and source amplitudes. Thermal simulations ensured that temperature rises were <0.5 °C at the target and <3 °C in the skull. To test for non-specific auditory activation, TUS (500 kHz, 300 ms burst, modulated at 1 kHz with 50% duty cycle) was applied to primary visual cortex and participants were asked to distinguish stimulation from non-stimulation trials. EEG was recorded throughout the task. Furthermore, ex-vivo skull experiments tested for the presence of skull vibrations during TUS. We found that participants can hear sound during TUS and can distinguish between stimulation and non-stimulation trials. This was corroborated by EEG recordings indicating auditory activation associated with TUS. Delivering an audio waveform to participants through earphones while TUS was applied reduced detection rates to chance level and abolished the TUS-induced auditory EEG signal. Ex vivo skull experiments demonstrated that sound is conducted through the skull at the pulse repetition frequency of the ultrasound. Future studies using TUS in humans need to take this auditory confound into account and mask stimulation appropriately. Transcranial ultrasound stimulation elicits auditory signals in humans. Healthy human participants can distinguish stimulation from non-stimulation trials. Auditory masking reduces detection rates. Skull vibrations are present during transcranial ultrasound stimulation. The auditory signal is likely due to bone conduction at the pulse repetition frequency.