Popelár J, Nwabueze-Ogbo F C, Syka J
Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic.
Physiol Res. 2003;52(5):615-28.
The role of cortico-tectal pathways in auditory signal processing was studied in anesthetized rats by comparing the extracellular single unit activity in the inferior colliculus (IC) before and after functional ablation of the auditory cortex (AC) by tetrodotoxin (TTX). The responses of several IC neurons to sound stimuli were simultaneously recorded with a 16-channel electrode probe introduced into the IC. Click-evoked middle latency responses (MLR) recorded from the AC were suppressed for several hours after TTX injection. During AC inactivation the firing rate of IC neurons increased (40 % of neurons), decreased (44 %) or did not change (16 %) in comparison with control conditions. In several IC neurons, TTX injection resulted in alterations in the shape of the rate-level functions. Response thresholds, tuning properties and the type of discharge pattern of IC neurons were not altered during AC inactivation. However, in one-third of the neurons, the initial part of the response was less altered than the later, sustained part. In two-thirds of neuronal pairs, functional decortication resulted in a change in the cross-correlation coefficient. The results reveal the complex changes that appear in IC neuronal activity after functional ablation of the ipsilateral auditory cortex.
通过比较用河豚毒素（TTX）功能性损毁听觉皮层（AC）前后麻醉大鼠下丘（IC）的细胞外单单位活动，研究了皮质-顶盖通路在听觉信号处理中的作用。用插入IC的16通道电极探针同时记录多个IC神经元对声音刺激的反应。TTX注射后，从AC记录到的短声诱发的中潜伏期反应（MLR）被抑制了几个小时。与对照条件相比，在AC失活期间，IC神经元的放电率增加（40%的神经元）、降低（44%）或不变（16%）。在几个IC神经元中，TTX注射导致放电率-强度函数的形状发生改变。在AC失活期间，IC神经元的反应阈值、调谐特性和放电模式类型没有改变。然而，在三分之一的神经元中，反应的初始部分比后期的持续部分变化小。在三分之二的神经元对中，功能性去皮质导致互相关系数发生变化。结果揭示了同侧听觉皮层功能性损毁后IC神经元活动出现的复杂变化。
