Chang Kelly H, Thomas Jessica M, Boynton Geoffrey M, Fine Ione
Department of Psychology, University of Washington, Seattle, WA, United States.
Front Psychol. 2017 Nov 14;8:1983. doi: 10.3389/fpsyg.2017.01983. eCollection 2017.
Here we show that, using functional magnetic resonance imaging (fMRI) blood-oxygen level dependent (BOLD) responses in human primary auditory cortex, it is possible to reconstruct the sequence of tones that a person has been listening to over time. First, we characterized the tonotopic organization of each subject's auditory cortex by measuring auditory responses to randomized pure tone stimuli and modeling the frequency tuning of each fMRI voxel as a Gaussian in log frequency space. Then, we tested our model by examining its ability to work in reverse. Auditory responses were re-collected in the same subjects, except this time they listened to sequences of frequencies taken from simple songs (e.g., "Somewhere Over the Rainbow"). By finding the frequency that minimized the difference between the model's prediction of BOLD responses and actual BOLD responses, we were able to reconstruct tone sequences, with mean frequency estimation errors of half an octave or less, and little evidence of systematic biases.
在此我们表明，利用人类初级听觉皮层中基于血氧水平依赖（BOLD）反应的功能磁共振成像（fMRI），可以重建一个人随着时间推移所听到的音调序列。首先，我们通过测量对随机纯音刺激的听觉反应，并将每个fMRI体素的频率调谐在对数频率空间中建模为高斯分布，来表征每个受试者听觉皮层的音调拓扑组织。然后，我们通过检验模型的反向工作能力来测试我们的模型。在同一受试者中重新收集听觉反应，只是这次他们听的是从简单歌曲（如《彩虹之上》）中选取的频率序列。通过找到使模型对BOLD反应的预测与实际BOLD反应之间差异最小化的频率，我们能够重建音调序列，平均频率估计误差在半个八度或更小，并且几乎没有系统偏差的迹象。
