Feng J J, Kuwada S, Ostapoff E M, Batra R, Morest D K
Department of Anatomy, University of Connecticut Health Center, Farmington 06030.
J Comp Neurol. 1994 Aug 1;346(1):1-18. doi: 10.1002/cne.903460102.
Neurons in the cochlear nucleus differ in their discharge patterns when stimulated by tones. They also differ in their responses to depolarizing current injection in vitro. We made intracellular recordings from neurons in the cochlear nucleus of gerbils and chinchillas. The responses to tones and to depolarizing current were compared for the same neurons. Three categories of response patterns to tones were observed: chopper, primary-like, and onset. Chopper neurons responded with regularly spaced action potentials to stimulation with tones and to injections of depolarizing current. Their response rate rose with increasing levels of current to a maximum, which was comparable to that evoked by suprathreshold tones. These observations suggest that the regularity and maximal firing rate of these neurons are determined by voltage-dependent membrane properties. Primary-like neurons responded with irregularly spaced action potentials to tones. Injection of depolarizing current into these neurons produced a single action potential at current onset, which could be followed by a few irregularly spaced action potentials. The response rate showed little relation to current level. These data suggest that the membrane characteristics of primary-like neurons are different from those of chopper neurons. Onset neurons produced action potentials only at the beginning of the stimulus for both tones and depolarizing current, even though there was a sustained depolarization throughout the duration of the tone. The findings suggest that cochlear nucleus neurons have different membrane properties and that these properties may play a critical role in a neuron's temporal response pattern to acoustic stimulation.
当受到音调刺激时，耳蜗核中的神经元放电模式有所不同。它们在体外对去极化电流注入的反应也存在差异。我们对沙鼠和毛丝鼠耳蜗核中的神经元进行了细胞内记录。对同一神经元的音调反应和去极化电流反应进行了比较。观察到对音调的三类反应模式：斩波型、初级样型和起始型。斩波型神经元对音调刺激和去极化电流注入以规则间隔的动作电位做出反应。它们的反应率随着电流水平的增加而上升至最大值，这与阈上音调所诱发的反应率相当。这些观察结果表明，这些神经元的规律性和最大放电率由电压依赖性膜特性决定。初级样型神经元对音调以不规则间隔的动作电位做出反应。向这些神经元注入去极化电流在电流开始时产生单个动作电位，随后可能会有一些不规则间隔的动作电位。反应率与电流水平关系不大。这些数据表明，初级样型神经元的膜特性与斩波型神经元不同。起始型神经元仅在音调刺激和去极化电流刺激开始时产生动作电位，尽管在整个音调持续期间存在持续的去极化。这些发现表明，耳蜗核神经元具有不同的膜特性，并且这些特性可能在神经元对声刺激的时间反应模式中起关键作用。
