AUGMENTATION OF EVOKED POTENTIALS FROM THE GUINEA PIG AUDITORY CORTEX AFTER EXPOSURE TO INTENSIVE NOISE

Evoked potential recorded from the guinea pig auditory cortex in response to high-intensityclicks was found to be systematically augmented as a result of exposure to noise in appropriatedosage which caused a moderate temporal response-threshold shift(16—48 dB,5—20 min afterexposure).The maximum post-exposure response amplitude might exceed the pre-exposure valueby 30—120%.No parallel amplitude increment was observed in cochlear potential and in evokedpotentials from the medial geniculate body,a fact indicating the cortical site of the mechanism under-lying such augmentation.     

强噪声作用后豚鼠听皮层诱发电位的增大

在适当剂量强噪声暴露后,豚鼠听皮层由较强短声诱发的电位振幅可以增大。脉冲噪声峰值150dB脉宽50ms100—500次,或146dB脉宽10ms2000次,或持续白噪声105dB15min,可使暴露后的最大电位比暴露前的增大30—120％,其潜伏期平均约延长15％,5—20min内的暂时性阈移为16—48dB。过大的暴露剂量则使电位变小。在皮层诱发电位增大的同时,耳蜗电位、内膝体及小脑诱发电位均不增大。皮层电位的增大现象不受麻醉、掩蔽及皮层表面放置马钱子素的影响。