Phasic and tonic cell types in the zebra finch auditory caudal mesopallium
Phasic and tonic cell types in the zebra finch auditory caudal mesopallium
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DOI：
10.1152/jn.00694.2017
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发表时间：
2018-03-01
影响因子：
2.5
通讯作者：
Meliza, C. Daniel
中科院分区：
文献类型：
--
作者：
Chen, Andrew N.;Meliza, C. Daniel
尾侧中皮层（CM）是鸣禽听觉通路中的一个皮质水平区域，在那里对熟悉的歌曲产生选择性的、不变的反应。为了表征执行此计算的细胞类型，我们从幼年斑胸草雀（Taeniopygia guttata）的两性脑切片中进行了全细胞记录。我们发现了三组具有不同放电模式的脊髓兴奋性神经元。紧张性细胞产生持续的反应，去极化阶跃电流，相位的细胞只产生了几个尖峰在发病时，和一个中间组也是相位，但响应高达几百毫秒。相细胞有较小的树突状领域，较高的静息电位，和强大的低阈值外向整流。用电压门控钾通道拮抗剂4-氨基吡啶和α-树毒素的药物治疗将相位放电转变为强直放电。当用宽带电流刺激时，相位细胞以高达20-30 Hz的频率一致地发射，而紧张性神经元对0-10 Hz左右的频率更敏感。峰值相干频率的分布与斑胸草雀鸣叫的时间调制率的分布相似。我们在单室生物物理模型中通过改变细胞大小和缓慢失活的低阈值钾电流（I LT）的大小来重现这些观察结果。这些数据表明，在CM的内在动力学匹配的时间统计的同种song.NEW &值得注意的是在鸣禽，尾部mesopallium是一个关键的大脑区域参与识别其他个体的歌曲。这项研究确定了三种细胞类型在这方面具有不同的放电模式（紧张，相位，和中间），反映了细胞大小和低阈值钾电流的差异。相放电神经元在哺乳动物听觉皮质中没有对应的神经元，能够更好地跟随歌曲频率的快速调制。
The caudal mesopallium (CM) is a cortical-level area in the songbird auditory pathway where selective, invariant responses to familiar songs emerge. To characterize the cell types that perform this computation, we made whole cell recordings from brain slices in juvenile zebra finches (Taeniopygia guttata) of both sexes. We found three groups of putatively excitatory neurons with distinct firing patterns. Tonic cells produced sustained responses to depolarizing step currents, phasic cells produced only a few spikes at the onset, and an intermediate group was also phasic but responded for up to a few hundred milliseconds. Phasic cells had smaller dendritic fields, higher resting potentials, and strong low-threshold outward rectification. Pharmacological treatment with voltage-gated potassium channel antagonists 4-aminopyridine and alpha-dendrotoxin converted phasic to tonic firing. When stimulated with broadband currents, phasic cells fired coherently with frequencies up to 20-30 Hz, whereas tonic neurons were more responsive to frequencies around 0-10 Hz. The distribution of peak coherence frequencies was similar to the distribution of temporal modulation rates in zebra finch song. We reproduced these observations in a single-compartment biophysical model by varying cell size and the magnitude of a slowly inactivating, low-threshold potassium current (I LT). These data suggest that intrinsic dynamics in CM are matched to the temporal statistics of conspecific song.NEW & NOTEWORTHY In songbirds, the caudal mesopallium is a key brain area involved in recognizing the songs of other individuals. This study identifies three cell types in this area with distinct firing patterns (tonic, phasic, and intermediate) that reflect differences in cell size and a low-threshold potassium current. The phasic-firing neurons, which do not have a counterpart in mammalian auditory cortex, are better able to follow rapid modulations at the frequencies found in song.