Steinschneider Mitchell, Fishman Yonatan I, Arezzo Joseph C
Department of Neurology, Rose F. Kennedy Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Cereb Cortex. 2008 Mar;18(3):610-25. doi: 10.1093/cercor/bhm094. Epub 2007 Jun 22.
Electroencephalography is increasingly being used to probe the functional organization of auditory cortex. Modulation of the electroencephalographic (EEG) signal by tones was examined in primary auditory cortex (A1) of awake monkeys. EEG data were measured at 4 laminar depths defined by current source density profiles evoked by best frequency (BF) tones. Midlaminar multiunit activity was used to define the tuning characteristics of A1 sites. Presentation of BF tones increased EEG power across the range of frequencies examined (4-290 Hz), with maximal effects evident within the first 100 ms after stimulus onset. The largest relative increases in EEG power generally occurred at very high gamma frequency bands (130-210 Hz). Increases in EEG power for frequencies less than 70 Hz primarily represented changes in phase-locked activity, whereas increases at higher frequencies primarily represented changes in non-phase-locked activity. Power increases in higher gamma bands were better correlated with the A1 tonotopic organization than power increases in lower frequency bands. Results were similar across the 4 laminar depths examined. These findings highlight the value of examining high-frequency EEG components in exploring the functional organization of auditory cortex and may enhance interpretation of related studies in humans.
脑电图正越来越多地用于探究听觉皮层的功能组织。在清醒猴子的初级听觉皮层（A1）中，研究了音调对脑电图（EEG）信号的调制。在由最佳频率（BF）音调诱发的电流源密度分布所定义的4个层深测量EEG数据。中层多单位活动用于定义A1位点的调谐特性。呈现BF音调会增加所检查频率范围内（4 - 290 Hz）的EEG功率，在刺激开始后的前100毫秒内效果最为明显。EEG功率的最大相对增加通常出现在非常高的伽马频段（130 - 210 Hz）。低于70 Hz频率的EEG功率增加主要代表锁相活动的变化，而较高频率的增加主要代表非锁相活动的变化。较高伽马频段的功率增加与A1音调组织的相关性比低频段的功率增加更好。在所检查的4个层深中结果相似。这些发现突出了在探索听觉皮层功能组织时检查高频EEG成分的价值，并可能增强对人类相关研究的解释。
