Physiological and neural network studies on phoneme analysis by the auditory cortex

尽管有许多电生理学、心理学和信息工程学的研究，但听觉皮层提取听觉信息的神经机制尚不清楚。在本研究中，我们使用光学记录方法和听觉皮层处理声音的时频的NERD模型，研究了听觉皮层提取音素特征的可能机制。用12×12通道光电二极管阵列和电压敏感染料(RH795)对豚鼠听皮层进行光学记录，豚鼠用Nembutal(30 mg/kg)和神经降压止痛剂(多哌啶0.3 mg/kg/h和五唑卡因1.1 mg/kg/h)麻醉。研究了纯音、调频(FM)声和双调频复合声(CFM)出现在记录皮层对侧耳朵时的时空反应。不同频率的纯音刺激清楚地显示了原始奥迪…的等频带和立位组织更多的保守派皮质(AI)。作为对调频声音的反应，活动点在等频段内倾斜移动。当频率扫描方向改变时，活动光点朝相反的方向移动。基于这些结果，我们提出了波声图假说，并利用具有兴奋性和抑制性连接的二维分布神经振荡器建立了听觉皮质的神经网络模型。计算机模拟显示，该模型重建了在听觉皮质中观察到的活动(波)传播的基本特征。此外，仿真还表明了局部连接对波传播的重要贡献。侧向抑制对听觉皮质上活性部位的定位是必要的。此外，由于波传播的同步化和去同步化的分叉依赖于相邻兴奋性连接和侧向抑制之间的平衡，这些结果表明声音是由听觉皮质中动态的时空神经活动来表征的，为听觉识别中的特征和发音提供了一种新的方法。较少

Neural mechanism of auditory cortex for extraction of the auditory information has not yet known despite many electrophysiological, Psychological and information engineering studies. In this research, we have investigated a possible mechanism of the auditory cortex for feature extraction of phoneme by using an optical recording method and a nerd model of the auditory cortex that process spectro-temporal of sounds.Optical recording with a 12×12-channel photodiode array and a voltage-sensitive dye (RH795) was made from the auditory cortex a guinea pigs anesthetized by Nembutal (30 mg/kg) and neuroleptanalgesic (doroperidol 0.3 mg/kg/h and pentazocine 1.1 mg/kg/h). Spatio-temporal responses to pure tones, frequency-modulated (FM) sounds and a complex sound with two FM components (CFM) presented to the ear contralateral to the recording cortex were studied. Pure ton stimulation at different frequencies clearly showed the isofrequency bands and the tonotopic organization in the primary audi … More tory cortex (AI). In response to FM sounds, the active spot moved obliquely crossing the isofrequency bands. When the direction of the frequency sweep was changed, the active spot moved in the opposite direction. The response to the CFM was complex : active spot to each FM component moved obliquely crossing the isofrequency bands with mutual inhibition.Based on these results, we proposed a wave sonagram hypothesis and made a neural network model of the auditory cortex using 2-dimensionally distributed neural oscillators with excitatory and inhibitory connections. Computer simulation revealed that the model reconstructed the fundamental characteristics of the activity (wave) propagation observed in the auditory cortex. Furthermore, the simulation demonstrated the important contribution of local connections for the wave propagation. The lateral inhibition is necessary for the localization of the active site on the auditory cortex. Furthermore, for the bifurcation of synchronization - desynchronization of the wave propagation depends on the balance between the neighboring excitatory connections and the lateral inhibition.These results indicate sounds were represented by dynamic spatio-temporal neural activities in the auditory cortex and propose a novel way of feature and articulation in the auditory recognition. Less