Stimulus feature selectivity in excitatory and inhibitory neurons in primary visual cortex
Stimulus feature selectivity in excitatory and inhibitory neurons in primary visual cortex
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DOI：
10.1523/jneurosci.1692-07.2007
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发表时间：
2007-09-26
影响因子：
5.3
通讯作者：
Contreras, Diego
中科院分区：
文献类型：
--
作者：
Cardin, Jessica A.;Palmer, Larry A.;Contreras, Diego
虽然一些证据表明，躯体感觉和视觉皮质的刺激选择性严重依赖于非选择性抑制，特别是在丘脑第四层，但尚未对兴奋性和抑制性细胞的反应进行全面的比较。在这里，我们在细胞内记录了初级视皮层2-6层的大量规则峰(RS；假定为兴奋性)和快速峰(FS；假定为抑制性)细胞。在第4层，首先出现了取向和空间频率的选择性，我们没有发现未调谐的FS细胞。相反，第4层FS细胞的棘波输出的调谐比RS细胞明显但中等宽。然而，基本突触反应的调谐并没有不同，这表明突触输入到放电频率转换的不同导致了峰-输出选择性的差异。与第4层RS细胞相比，第4层FS细胞表现出更低的输入电阻和更快的时间常数，导致更大和更快的膜电位(V-m)波动。与RS细胞相比，FS细胞的V-m波动的调谐范围更广，并且与尖峰输出调谐相匹配，这表明这些细胞的更广泛的尖峰调谐是由视觉诱发的突触噪声驱动的。这些差异在第四层之外是观察不到的。因此，在皮质感觉加工的第一水平上，细胞类型特定的刺激特征选择性的差异可能是决定突触整合动力学的不同生物物理性质的结果。
Although several lines of evidence suggest that stimulus selectivity in somatosensory and visual cortices is critically dependent on unselective inhibition, particularly in the thalamorecipient layer 4, no comprehensive comparison of the responses of excitatory and inhibitory cells has been conducted. Here, we recorded intracellularly from a large population of regular spiking (RS; presumed excitatory) and fast spiking (FS; presumed inhibitory) cells in layers 2-6 of primary visual cortex. In layer 4, where selectivity for orientation and spatial frequency first emerges, we found no untuned FS cells. Instead, the tuning of the spike output of layer 4 FS cells was significantly but moderately broader than that of RS cells. However, the tuning of the underlying synaptic responses was not different, indicating that the difference in spike-output selectivity resulted from differences in the transformation of synaptic input into firing rate. Layer 4 FS cells exhibited significantly lower input resistance and faster time constants than layer 4 RS cells, leading to larger and faster membrane potential (V-m) fluctuations. FS cell V-m fluctuations were more broadly tuned than those of RS cells and matched spike-output tuning, suggesting that the broader spike tuning of these cells was driven by visually evoked synaptic noise. These differences were not observed outside of layer 4. Thus, cell type-specific differences in stimulus feature selectivity at the first level of cortical sensory processing may arise as a result of distinct biophysical properties that determine the dynamics of synaptic integration.