Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, Australia.
Neurocure Center for Excellence, Charité Universitätsmedizin Berlin and Humboldt Universität, Berlin, Germany.
Elife. 2022 Mar 17;11:e73406. doi: 10.7554/eLife.73406.
Feedforward inhibitory circuits are key contributors to the complex interplay between excitation and inhibition in the brain. Little is known about the function of feedforward inhibition in the primary olfactory (piriform) cortex. Using in vivo two-photon-targeted patch clamping and calcium imaging in mice, we find that odors evoke strong excitation in two classes of interneurons - neurogliaform (NG) cells and horizontal (HZ) cells - that provide feedforward inhibition in layer 1 of the piriform cortex. NG cells fire much earlier than HZ cells following odor onset, a difference that can be attributed to the faster odor-driven excitatory synaptic drive that NG cells receive from the olfactory bulb. As a result, NG cells strongly but transiently inhibit odor-evoked excitation in layer 2 principal cells, whereas HZ cells provide more diffuse and prolonged feedforward inhibition. Our findings reveal unexpected complexity in the operation of inhibition in the piriform cortex.
前馈抑制回路是大脑中兴奋和抑制之间复杂相互作用的关键贡献者。关于初级嗅觉（梨状）皮层中前馈抑制的功能知之甚少。我们使用体内双光子靶向贴片钳和钙成像在小鼠中发现，气味会在梨状皮层 1 层中引发两种中间神经元 - 神经胶质形成细胞（NG 细胞）和水平（HZ 细胞） - 的强烈兴奋，这些细胞提供前馈抑制。与气味驱动的兴奋性突触驱动相比，NG 细胞更早地发射气味，这可以归因于更快的气味驱动兴奋性突触驱动，NG 细胞从嗅球接收。结果，NG 细胞强烈但短暂地抑制了层 2 主细胞中的气味诱发兴奋，而 HZ 细胞提供了更弥散和持续的前馈抑制。我们的发现揭示了梨状皮层中抑制作用的出人意料的复杂性。
