Romani G L, Williamson S J, Kaufman L, Brenner D
Exp Brain Res. 1982;47(3):381-93. doi: 10.1007/BF00239356.
Neuromagnetic studies show that the location of cortical activity evoked by modulated tones and by click stimuli in the steady state paradigm can be determined non-invasively with a precision of a few millimeters. The progression of locations for tones of increasing frequency establish an orderly tonotopic map in which the distance along the cortex varies as the logarithm of the frequency. The active region responding to clicks lies at a position that is consistent with this map if the stimulus is characterized by the frequency of the peak of its power spectrum. A latency of about 50 ms observed for the response to clicks is in close correspondence with a strong component of the transient response to an isolated click reported in the literature. Monaural stimulation of the ear contralateral to the hemisphere being monitored produces a latency which is about 8 ms shorter than stimulation of the ipsilateral ear, in agreement with previous studies of transient responses. The amplitudes of the responses for binaurally presented clicks for sleeping subjects is substantially diminished for repetition rates above 20 Hz but is enhanced for lower rates.
神经磁学研究表明，在稳态范式中，由调制音调以及点击刺激诱发的皮层活动位置可以通过非侵入性方法确定，精度可达几毫米。随着频率增加，音调诱发的活动位置变化形成了一个有序的音频定位图谱，其中沿着皮层的距离随频率的对数而变化。如果点击刺激以其功率谱峰值频率为特征，那么对点击作出反应的活跃区域位于与该图谱一致的位置。观察到对点击反应的潜伏期约为50毫秒，这与文献中报道的对单个点击的瞬态反应的一个强成分密切对应。对被监测半球对侧耳朵进行单耳刺激产生的潜伏期比对同侧耳朵刺激产生的潜伏期短约8毫秒，这与之前对瞬态反应的研究结果一致。对于睡眠中的受试者，当双耳呈现点击刺激的重复率高于20赫兹时，反应幅度会大幅减小，但在较低重复率时会增强。
