Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA.
Harvard Medical School, Boston, MA 02115, USA.
Neuron. 2019 Nov 6;104(3):451-457.e3. doi: 10.1016/j.neuron.2019.08.004. Epub 2019 Sep 5.
Understanding how cortical inhibition shapes circuit function requires identifying the connectivity rules relating the response properties of inhibitory interneurons and their postsynaptic targets. Here we explore the orientation tuning of layer 2/3 inhibitory inputs in the ferret visual cortex using a combination of in vivo axon imaging, functional input mapping, and physiology. Inhibitory boutons exhibit robust orientation-tuned responses with preferences that can differ significantly from the cortical column in which they reside. Inhibitory input fields measured with patterned optogenetic stimulation and intracellular recordings revealed that these inputs originate from a wide range of orientation domains, inconsistent with a model of co-tuned inhibition and excitation. Intracellular synaptic conductance measurements confirm that individual neurons can depart from a co-tuned regime. Our results argue against a simple rule for the arrangement of inhibitory inputs supplied by layer 2/3 circuits and suggest that heterogeneity in presynaptic inhibitory networks contributes to neural response properties.
理解皮质抑制如何塑造电路功能需要确定与抑制性中间神经元及其突触后靶标反应特性相关的连接规则。在这里，我们使用体内轴突成像、功能输入映射和生理学方法来探索雪貂视觉皮层中第 2/3 层抑制性输入的方向调谐。抑制性末梢具有强烈的方向调谐反应，其偏好与它们所在的皮质柱可以有很大的不同。使用图案光遗传学刺激和细胞内记录测量的抑制性输入场表明，这些输入源自广泛的方向域，与共调抑制和兴奋的模型不一致。细胞内突触电导测量证实，单个神经元可以偏离共调状态。我们的结果反对由第 2/3 层电路提供的抑制性输入的简单排列规则，并表明突触前抑制性网络的异质性有助于神经反应特性。
