Biological Sciences, University of Missouri, 207 Tucker Hall, Columbia, MO 65211, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2012 Sep;198(9):695-704. doi: 10.1007/s00359-012-0740-3. Epub 2012 Jun 26.
The detection of novel signals in the auditory scene is an elementary task of any hearing system. In Neoconocephalus katydids, a primary auditory interneuron (TN-1) with broad spectral sensitivity, responded preferentially to rare deviant pulses (7 pulses/s repetition rate) embedded among common standard pulses (140 pulses/s repetition rate). Eliminating inhibitory input did not affect the detection of the deviant pulses. Detection thresholds for deviant pulses increased significantly with increasing amplitude of standard pulses. Responses to deviant pulses occurred when the carrier frequencies of deviant and standard were sufficiently different, both when the deviant had a higher or lower carrier frequency than the standard. Recordings from receptor neurons revealed that TN-1 responses to the deviant pulses did not depend on the population response strength of the receptors, but on the distribution of the receptor cell activity. TN-1 responses to the deviant pulse occurred only when the standard and deviant pulses were transmitted by different groups of receptor cells. TN-1 responses parallel stimulus specific adaptation (SSA) described in mammalian auditory system. The results support the hypothesis that the mechanisms underlying SSA and change-detection are located in the TN-1 dendrite, rather than the receptor cells.
在任何听觉系统中，检测听觉场景中的新信号都是基本任务。在 Neoconocephalus katydids 中，一种具有广谱敏感性的初级听觉中间神经元（TN-1）对罕见的偏差脉冲（7 脉冲/秒重复率）优先反应，这些偏差脉冲嵌入在常见的标准脉冲（140 脉冲/秒重复率）中。消除抑制性输入并不会影响对偏差脉冲的检测。偏差脉冲的检测阈值随着标准脉冲幅度的增加而显著增加。当偏差和标准的载波频率足够不同时，无论是偏差的载波频率高于还是低于标准的载波频率，都会发生对偏差脉冲的反应。来自感受器神经元的记录显示，TN-1 对偏差脉冲的反应并不取决于感受器的群体反应强度，而是取决于感受器细胞活动的分布。只有当标准脉冲和偏差脉冲由不同的感受器细胞群传输时，TN-1 才会对偏差脉冲产生反应。TN-1 对偏差脉冲的反应与哺乳动物听觉系统中描述的刺激特异性适应（SSA）平行。结果支持了这样的假设，即 SSA 和变化检测的机制位于 TN-1 树突中，而不是感受器细胞中。
