Defitech Chair in Brain-Machine Interface, Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.
Cereb Cortex. 2018 Dec 1;28(12):4222-4233. doi: 10.1093/cercor/bhx277.
Despite many behavioral and neuroimaging investigations, it remains unclear how the human cortex represents spectrotemporal sound features during auditory imagery, and how this representation compares to auditory perception. To assess this, we recorded electrocorticographic signals from an epileptic patient with proficient music ability in 2 conditions. First, the participant played 2 piano pieces on an electronic piano with the sound volume of the digital keyboard on. Second, the participant replayed the same piano pieces, but without auditory feedback, and the participant was asked to imagine hearing the music in his mind. In both conditions, the sound output of the keyboard was recorded, thus allowing precise time-locking between the neural activity and the spectrotemporal content of the music imagery. This novel task design provided a unique opportunity to apply receptive field modeling techniques to quantitatively study neural encoding during auditory mental imagery. In both conditions, we built encoding models to predict high gamma neural activity (70-150 Hz) from the spectrogram representation of the recorded sound. We found robust spectrotemporal receptive fields during auditory imagery with substantial, but not complete overlap in frequency tuning and cortical location compared to receptive fields measured during auditory perception.
尽管进行了许多行为和神经影像学研究，但仍不清楚人类大脑皮层在听觉想象过程中如何表示声音的频谱和时变特征，以及这种表示与听觉感知有何不同。为了评估这一点，我们在 2 种条件下记录了一位具有出色音乐能力的癫痫患者的脑电信号。首先，参与者在电子钢琴上弹奏了 2 首钢琴曲，同时打开了数字键盘的音量。其次，参与者重复弹奏相同的钢琴曲，但没有听觉反馈，并要求参与者在脑海中想象听到音乐。在这两种情况下，键盘的声音输出都被记录下来，从而可以在神经活动和音乐想象的频谱内容之间实现精确的时间锁定。这种新颖的任务设计为应用感受野建模技术定量研究听觉心理想象过程中的神经编码提供了独特的机会。在这两种情况下，我们都构建了编码模型，以从记录声音的频谱图表示中预测高伽马神经活动（70-150 Hz）。我们发现，在听觉想象过程中存在强大的频谱和时间感受野，与听觉感知期间测量的感受野相比，其频率调谐和皮层位置存在显著但不完全重叠。
