Thomas Connon I, Ryan Melissa A, Kamasawa Naomi, Scholl Benjamin
Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA.
Present Address: Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA.
bioRxiv. 2023 Sep 25:2023.07.14.549063. doi: 10.1101/2023.07.14.549063.
Postsynaptic mitochondria are critical to the development, plasticity, and maintenance of synaptic inputs. However, their relationship to synaptic structure and functional activity is unknown. We examined a correlative dataset from ferret visual cortex with two-photon calcium imaging of dendritic spines during visual stimulation and electron microscopy (EM) reconstructions of spine ultrastructure, investigating mitochondrial abundance near functionally- and structurally-characterized spines. Surprisingly, we found no correlation to structural measures of synaptic strength. Instead, we found that mitochondria are positioned near spines with orientation preferences that are dissimilar to the somatic preference. Additionally, we found that mitochondria are positioned near groups of spines with heterogeneous orientation preferences. For a subset of spines with mitochondrion in the head or neck, synapses were larger and exhibited greater selectivity to visual stimuli than those without a mitochondrion. Our data suggest mitochondria are not necessarily positioned to support the energy needs of strong spines, but rather support the structurally and functionally diverse inputs innervating the basal dendrites of cortical neurons.
突触后线粒体对于突触输入的发育、可塑性和维持至关重要。然而，它们与突触结构和功能活动之间的关系尚不清楚。我们研究了雪貂视觉皮层的一个相关数据集，该数据集包括视觉刺激期间树突棘的双光子钙成像以及棘突超微结构的电子显微镜（EM）重建，研究功能和结构特征明确的棘突附近的线粒体丰度。令人惊讶的是，我们发现与突触强度的结构测量值没有相关性。相反，我们发现线粒体位于棘突附近，其取向偏好与体细胞偏好不同。此外，我们发现线粒体位于取向偏好异质的棘突群附近。对于头部或颈部有线粒体的一部分棘突，突触比没有线粒体的突触更大，并且对视觉刺激表现出更高的选择性。我们的数据表明，线粒体不一定是为了支持强棘突的能量需求而定位的，而是支持支配皮层神经元基底树突的结构和功能多样的输入。
