Schürmann M, Başar E
Institut für Physiologie, Medizinische Universität zu Lübeck, Germany.
Biol Cybern. 1994;72(2):161-74. doi: 10.1007/BF00205980.
Brain resonance phenomena and induced rhythms in the brain recently gained importance in electroencephalographic, magnetoencephalographic and cellular studies (Başar and Bullock 1992). It was hypothesized that evoked potentials are superpositions of induced rhythms caused by resonance phenomena in neural populations (Başar et al. 1992). According to Başar (1972), such resonance phenomena are reflected in the main peaks of the amplitude frequency characteristics computed from EEG responses. The present study is based on a frequency domain approach for the evaluation of topography- and modality-dependent properties of oscillatory brain responses. EEG and evoked potentials were recorded from vertex, parietal and occipital scalp locations in 24 volunteers. Two combined methods were applied: (1) amplitude frequency characteristics were computed from the transient evoked responses, and (2) frequency components of the transient responses were obtained by adaptive digital filtering. Our main goal was to investigate theta (4-7 Hz) and alpha (8-15 Hz) response components. (1) Amplitude frequency characteristics. Auditory stimuli elicited theta-alpha compound responses in the 4-11 Hz frequency band (e.g. typical peaking frequency around 7 Hz for vertex recordings). Visual stimuli elicited alpha responses (e.g. typical peaking frequency for vertex recordings around 9-12 Hz). Frequency maxima for visual stimuli thus had main peaks at higher frequency values than frequency maxima for auditory stimuli. (2) Digital filtering confirmed these results: for vertex recordings, theta vs. alpha response amplitudes were 9 muV vs 6 muV for auditory stimuli and 5 muV vs 5 muV for visual stimuli, thus confirming a shift towards higher frequencies, i.e. a more prominent contribution of the alpha range, in the case of visual stimulation. We hypothesize that these properties might reflect site- and modality-specific features of stimulus encoding in the brain in which resonance properties of neuron populations are involved. Furthermore we emphasize the utility of the systems theory approach for a better understanding of brain function by means of EPs.
脑共振现象以及大脑中的诱发电节律最近在脑电图、脑磁图和细胞研究中变得越发重要（巴萨尔和布洛克，1992年）。有人提出假设，诱发电位是神经群体中共振现象所引发的诱发电节律的叠加（巴萨尔等人，1992年）。根据巴萨尔（1972年）的观点，此类共振现象反映在根据脑电图反应计算出的幅度频率特性的主要峰值中。本研究基于频域方法，用于评估振荡性脑反应的地形学和模态依赖性特性。在24名志愿者的头顶、顶叶和枕叶头皮部位记录了脑电图和诱发电位。应用了两种组合方法：（1）从瞬态诱发电反应中计算幅度频率特性；（ii）通过自适应数字滤波获得瞬态反应的频率成分。我们的主要目标是研究θ（4 - 7赫兹）和α（8 - 15赫兹）反应成分。（1）幅度频率特性。听觉刺激在4 - 11赫兹频段引发了θ - α复合反应（例如，头顶记录的典型峰值频率约为7赫兹）。视觉刺激引发了α反应（例如，头顶记录的典型峰值频率约为9 - 12赫兹）。因此，视觉刺激的频率最大值的主要峰值频率值高于听觉刺激的频率最大值。（2）数字滤波证实了这些结果：对于头顶记录，听觉刺激的θ与α反应幅度分别为9微伏和6微伏，视觉刺激的分别为5微伏和5微伏，从而证实了在视觉刺激情况下向更高频率的转变，即α范围的贡献更为突出。我们假设这些特性可能反映了大脑中刺激编码的部位和模态特异性特征，其中涉及神经元群体的共振特性。此外，我们强调系统理论方法对于通过诱发电位更好地理解脑功能的实用性。
