Song You-Hyang, Hwang Yang-Sun, Kim Kwansoo, Lee Hyoung-Ro, Kim Jae-Hyun, Maclachlan Catherine, Dubois Anaelle, Jung Min Whan, Petersen Carl C H, Knott Graham, Lee Suk-Ho, Lee Seung-Hee
Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea.
Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
Sci Adv. 2020 Apr 22;6(17):eaaz0517. doi: 10.1126/sciadv.aaz0517. eCollection 2020 Apr.
Somatostatin (SST) is a neuropeptide expressed in a major subtype of GABAergic interneurons in the cortex. Despite abundant expression of SST and its receptors, their modulatory function in cortical processing remains unclear. Here, we found that SST application in the primary visual cortex (V1) improves visual discrimination in freely moving mice and enhances orientation selectivity of V1 neurons. We also found that SST reduced excitatory synaptic transmission to parvalbumin-positive (PV) fast-spiking interneurons but not to regular-spiking neurons. Last, using serial block-face scanning electron microscopy (SBEM), we found that axons of SST neurons in V1 often contact other axons that exhibit excitatory synapses onto the soma and proximal dendrites of the PV neuron. Collectively, our results demonstrate that the neuropeptide SST improves visual perception by enhancing visual gain of V1 neurons via a reduction in excitatory synaptic transmission to PV inhibitory neurons.
生长抑素（SST）是一种在皮质中γ-氨基丁酸能中间神经元的主要亚型中表达的神经肽。尽管SST及其受体表达丰富，但其在皮质处理过程中的调节功能仍不清楚。在这里，我们发现，在初级视觉皮层（V1）中应用SST可改善自由活动小鼠的视觉辨别能力，并增强V1神经元的方向选择性。我们还发现，SST减少了对小白蛋白阳性（PV）快速放电中间神经元的兴奋性突触传递，但对常规放电神经元则没有影响。最后，使用连续块面扫描电子显微镜（SBEM），我们发现V1中SST神经元的轴突经常与其他轴突接触，这些轴突在PV神经元的胞体和近端树突上表现出兴奋性突触。总的来说，我们的结果表明，神经肽SST通过减少对PV抑制性神经元的兴奋性突触传递来增强V1神经元的视觉增益，从而改善视觉感知。
